AUTOSAR E2E Profile 5 Explained: CRC-16 CCITT, 3-Byte Header, and CAN FD Ethernet Protection

AUTOSAR E2E Profile 5 occupies a uniquely valuable position in the AUTOSAR End-to-End Communication Protection library – sitting precisely between the compact 8-bit CRC profiles designed for classic CAN and the heavyweight 32-bit and 64-bit CRC profiles designed for FlexRay and large Ethernet payloads. With its CRC-16 CCITT polynomial (0x1021) and a compact 3-byte header containing a 16-bit CRC, an 8-bit sequence counter, and a configurable offset for flexible placement within any data element, AUTOSAR E2E Profile 5 delivers exactly the right balance of protection strength and overhead efficiency for the modern CAN FD and Automotive Ethernet era.

As vehicles transition from classic CAN’s 8-byte payloads to CAN FD‘s 64-byte payloads and compact Ethernet messages, engineers face a design challenge that neither the 8-bit CRC profiles (too weak for longer messages) nor the 12-byte Profile 4 header (too heavy for shorter messages) adequately solves. AUTOSAR E2E Profile 5 CAN FD Ethernet protection resolves this challenge elegantly: a 16-bit CRC provides substantially stronger fault coverage than 8-bit CRCs for medium-length messages, while the E2E Profile 5 3-byte header adds only minimal overhead to payloads that range from a few bytes up to 4096 bytes. This makes AUTOSAR E2E Profile 5 the practical choice for a broad range of automotive functional safety ISO 26262 ASIL D E2E CRC16 deployments across the rapidly evolving automotive network landscape.

This comprehensive guide covers every technical aspect of AUTOSAR E2E Profile 5: the CRC-16 CCITT polynomial mathematics and why it was chosen, the precise 3-byte header layout with configurable offset, the full protect and check API with C implementation examples, state machine configuration for ASIL D, real-world CAN FD and Ethernet use cases, and a thorough comparison with related profiles including Profile 4 and Profile 6.

🔗 Part of the AUTOSAR E2E Master Series on PiEmbSysTech.
Parent page: AUTOSAR E2E Communication Protection: Complete Technical Guide

1. What is AUTOSAR E2E Profile 5?

AUTOSAR E2E Profile 5 is a standardized End-to-End (E2E) safety communication protocol defined in the AUTOSAR E2E Protocol Specification (PRS_E2EProtocol) and SW-C E2E Library Specification (SWS_E2ELibrary). Introduced in AUTOSAR Release 4.1 to address the growing CAN FD and Automotive Ethernet ecosystem, it provides a 16-bit CRC-based protection scheme specifically designed for data elements that are too long for the 8-bit CRC profiles (Profiles 1 and 2) but do not require the full 12-byte header weight of Profile 4.

Three core mechanisms work together in AUTOSAR E2E Profile 5:

CRC-16 CCITT (polynomial 0x1021): A 16-bit cyclic redundancy check using the widely proven CCITT polynomial, providing stronger fault coverage than 8-bit CRCs for payloads up to 4096 bytes
8-bit Sequence Counter (0–255): An incrementing counter embedded in the header, detecting lost messages, repeated messages, wrong sequences, and timeouts
16-bit Data ID (implicit in CRC): A unique identifier incorporated into the CRC computation but NOT transmitted in the header, protecting against masquerade without consuming header bytes

What makes AUTOSAR E2E Profile 5 strategically significant is the combination of its compact 3-byte header (2 bytes CRC-16 + 1 byte counter) and its configurable offset parameter – allowing the E2E header to be placed at any byte-aligned position within the data element. For CAN FD with 64-byte payloads, the 3-byte overhead represents less than 5% of the payload. For a 100-byte Ethernet message, it is only 3%. This efficiency at scale makes AUTOSAR E2E Profile 5 CAN FD Ethernet protection the pragmatic choice for a wide range of mid-length safety-critical data elements.

📌 Quick Reference — AUTOSAR E2E Profile 5 at a Glance

Profile Identifier	E2E_05 (AUTOSAR Standard Profile)
CRC Algorithm	CRC-16-CCITT, polynomial 0x1021 (x¹⁶+x¹²+x⁵+1), Start: 0xFFFF, XOR: 0x0000
Counter	8-bit (0–255), all values valid, wraps 255→0
Data ID	16-bit, implicit – NOT transmitted in header, included in CRC computation
Header Size	3 bytes (2B CRC-16 + 1B Counter)
Header Position	Configurable via `Offset` parameter (bits, multiple of 8). Default: 0.
Header Byte Order	Big Endian for CRC-16 (MSB at lower address)
Maximum Data Length	4096 bytes (32,768 bits)
Primary Bus Targets	CAN FD, Automotive Ethernet, moderate-length data on any AUTOSAR bus
Maximum ASIL	ASIL D (with safety analysis)
CRC Library Function	`Crc_CalculateCRC16()` from AUTOSAR CRC module
Platform Support	AUTOSAR Classic Platform (CP) and Adaptive Platform (AP)
Introduced In	AUTOSAR Release 4.1
AUTOSAR Standard	AUTOSAR_PRS_E2EProtocol, AUTOSAR_SWS_E2ELibrary

2. History and Background of AUTOSAR E2E Profile 5

AUTOSAR E2E Profile 5 was introduced in AUTOSAR Release 4.1 (2013), a period when the automotive industry was beginning its transition from classic CAN to CAN FD (Controller Area Network with Flexible Data-rate) and the earliest deployments of Automotive Ethernet (100BASE-T1) were appearing in premium vehicles.

The trigger for Profile 5’s introduction was a gap in the existing profile portfolio. Profile 4, introduced in Release 4.0, had filled the high-end need with its 32-bit CRC and 12-byte header – but for many CAN FD applications where payloads are 20–64 bytes, a 12-byte header represented 19–60% overhead, which was considered excessive. On the other side, Profiles 1 and 2 with their 8-bit CRCs and 30-byte maximum data length were insufficient for CAN FD’s 64-byte payloads and the emerging moderate-length Ethernet message requirements.

The design team for AUTOSAR E2E Profile 5 chose the CRC-16-CCITT polynomial (0x1021) as the foundation – not because it is the theoretically optimal 16-bit polynomial for all automotive message lengths, but because it is the most widely proven 16-bit CRC in telecommunications, serial communications, and industrial networking. Its field history is enormous: HDLC, SD cards, ITU-T standards, and countless embedded systems have validated its fault detection properties over decades. This “proven in use” rationale aligns directly with the AUTOSAR E2E philosophy stated in the requirements specification (SRS_E2E_08528).

The key innovation distinguishing AUTOSAR E2E Profile 5 from Profile 4 was the deliberate decision to not transmit the Data ID explicitly in the header. Unlike Profile 4’s 16-bit transmitted Data ID field, Profile 5 incorporates the Data ID only implicitly – through its inclusion in the CRC computation as a separate input. This kept the header at just 3 bytes while still providing Data ID-based masquerade protection, making AUTOSAR E2E Profile 5 significantly more bandwidth-efficient than Profile 4 for applications where the Data ID overhead matters.

3. AUTOSAR E2E Profile 5 in the AUTOSAR Architecture

AUTOSAR E2E Profile 5 sits at the same architectural position as all E2E profiles – at the boundary between the ASIL D-rated Application Layer and the QM-rated Basic Software stack. Its 16-bit CRC computation is handled by the AUTOSAR CRC Library via Crc_CalculateCRC16(), and both Classic Platform and Adaptive Platform support it, making AUTOSAR E2E Profile 5 CAN FD Ethernet protection viable across the broadest range of modern automotive ECU architectures.

╔═══════════════════════════════════════════════════════════════════════╗
║                    APPLICATION LAYER (ASIL D)                         ║
║  ┌──────────────────────┐          ┌──────────────────────────────┐   ║
║  │  SW-C Sender          │          │  SW-C Receiver                │   ║
║  │  (e.g. BMS Controller)│          │  (e.g. Powertrain ECU)        │   ║
║  └──────────┬────────────┘          └──────────────┬───────────────┘   ║
║             │ E2E_P05Protect()                     │ E2E_P05Check()   ║
║             ▼                                      ▲                  ║
║  ┌──────────────────────────────────────────────────────────────────┐ ║
║  │           E2E LIBRARY — Profile 5  (ASIL D)                      │ ║
║  │  CRC-16-CCITT (0x1021) + 8-bit Counter + implicit 16-bit DataID  │ ║
║  │  calls Crc_CalculateCRC16() from CRC Library                     │ ║
║  │  3-byte header: [CRC-H][CRC-L][Counter] at configurable Offset   │ ║
║  └──────────────────────────────────────────────────────────────────┘ ║
╠═══════════════════════════════════════════════════════════════════════╣
║              RTE  (QM or ASIL D)                                       ║
╠═══════════════════════════════════════════════════════════════════════╣
║              BASIC SOFTWARE (QM)                                       ║
║  CAN FD Driver ──► CAN FD Controller                                   ║
║  Eth Driver ──► Ethernet Controller ──► UDP/TCP/SOME/IP                ║
╠═══════════════════════════════════════════════════════════════════════╣
║              CAN FD Bus  /  Automotive Ethernet Network                ║
╚═══════════════════════════════════════════════════════════════════════╝

Key architectural note:
• DataID (16-bit) is NEVER transmitted on the bus in Profile 5.
• It exists only in E2E_P05ConfigType.DataID on sender and receiver.
• CRC is computed over: [header bytes with CRC zeroed] + [signal data] + [DataID bytes]
• Independence from CAN FD hardware CRC and Ethernet HW CRC is guaranteed
  (0x1021 polynomial ≠ CAN CRC-15 ≠ CAN FD CRC-17/21 ≠ Ethernet CRC-32/IEEE 802.3)

A critical and often misunderstood point about AUTOSAR E2E Profile 5: the 16-bit Data ID is incorporated into the CRC computation as two separate bytes AFTER the signal data bytes – they are appended at the end of the CRC input stream, not transmitted in the message header. This is conceptually similar to Profile 2’s implicit DataID mechanism but simpler – a single static 16-bit Data ID rather than a rotating 16-entry list. The receiver independently applies the same Data ID bytes during its CRC recomputation, and any masquerade attempt (wrong Data ID) will cause a CRC mismatch.

4. AUTOSAR E2E Profile 5 – Complete Technical Specifications

Parameter	Value / Description
Profile Identifier	E2E_05
CRC Algorithm	CRC-16-CCITT, polynomial 0x1021 (x¹⁶+x¹²+x⁵+1), also known as CRC-16/CCITT-FALSE
CRC Start Value	0xFFFF
CRC XOR Output Value	0x0000 (no XOR applied to output)
CRC Input Reflection	FALSE (no bit reversal of input bytes)
CRC Output Reflection	FALSE (result not reflected)
CRC Field Size	16 bits (2 bytes), Big Endian at header Bytes [Offset] and [Offset+1]
CRC Library Function	`Crc_CalculateCRC16()` from AUTOSAR CRC module (CRC-16-CCITT)
Counter Field	8-bit (0–255), at header Byte [Offset+2]. Wraps 255→0. No reserved values.
Data ID Field	16-bit unique identifier. NOT transmitted in header. Included implicitly in CRC computation (low byte, then high byte, appended after signal data bytes).
Header Total Size	3 bytes (2B CRC + 1B Counter). Minimum overhead of any multi-byte CRC profile.
Header Byte Order	Big Endian for CRC-16: Byte[Offset] = CRC high byte, Byte[Offset+1] = CRC low byte
Header Offset	Configurable via `Offset` parameter (bits, multiple of 8). Allows E2E header at any byte-aligned position. Range: 0 ≤ Offset ≤ (MinDataLength – 24) bits.
CRC Computation Scope	Byte[Offset] to Byte[Offset+2] (with CRC bytes zeroed) + all signal data bytes + DataID low byte + DataID high byte (appended after signal data)
Minimum Data Length	3 bytes (24 bits) — the E2E header itself plus at least the Offset bytes before it
Maximum Data Length	4096 bytes (32,768 bits)
Variable-Length Data	Yes — MinDataLength and MaxDataLength configure the allowed range. Length field NOT in header (unlike Profile 4).
Supported Bus Types	CAN FD, Automotive Ethernet, intra-ECU communication, any AUTOSAR-supported bus
Platform Support	AUTOSAR Classic Platform (CP) and Adaptive Platform (AP)
Maximum ASIL Rating	ASIL D (with quantitative safety analysis per system)
Introduced In	AUTOSAR Release 4.1

5. The E2E Profile 5 3-Byte Header Layout – Bit-Level Detail

The E2E Profile 5 3-byte header is the most compact multi-byte-CRC header in the AUTOSAR E2E library. At just three bytes, it provides 16-bit CRC protection with minimal overhead – a critical advantage for AUTOSAR E2E Profile 5 CAN FD Ethernet deployments where payload space is precious.

E2E PROFILE 5 — 3-BYTE HEADER STRUCTURE (Offset = 0, Big Endian CRC)
═══════════════════════════════════════════════════════════════════════

Byte Index:   [Offset+0]        [Offset+1]        [Offset+2]
              ┌─────────────────┬─────────────────┬─────────────────┐
Content:      │   CRC-16 [15:8] │   CRC-16 [7:0]  │  Counter [7:0]  │
              │  (high byte)    │  (low byte)     │  (8-bit, 0–255) │
              └─────────────────┴─────────────────┴─────────────────┘
                ◄────── CRC-16 (Big Endian, 2 bytes) ──────►◄── 1B ──►

Signal data: Bytes [Offset+3] through [DataLength-1]

CRC Computation Order:
  Step 1: [Offset+0] = 0x00 (CRC high byte zeroed during computation)
  Step 2: [Offset+1] = 0x00 (CRC low byte zeroed during computation)
  Step 3: CRC-16 over: Bytes[Offset+0..Offset+2] (header, CRC=0x0000)
                     + Bytes[Offset+3..DataLength-1] (signal data)
                     + DataID_Low  (low byte of 16-bit Data ID)
                     + DataID_High (high byte of 16-bit Data ID)
  Result: Written into Bytes[Offset+0..Offset+1] in Big Endian order

EXAMPLE: 16-byte total payload (Offset=0, DataID=0x1234, Counter=42=0x2A)
  Byte[0] = 0xXX  (CRC high byte — computed result)
  Byte[1] = 0xXX  (CRC low byte — computed result)
  Byte[2] = 0x2A  (Counter = 42)
  Byte[3..15] = Signal data bytes (13 bytes of application signals)

  CRC input stream for verification:
    0x00, 0x00, 0x2A,     ← header (CRC zeroed, counter=42)
    data[3..15],           ← 13 signal bytes
    0x34, 0x12             ← DataID low byte (0x34), then high byte (0x12)

Why Only 3 Bytes?

The E2E Profile 5 3-byte header achieves its minimal footprint through two key design decisions. First, the 16-bit CRC requires exactly 2 bytes. Second, the 8-bit counter requires exactly 1 byte. No additional bytes are needed because the Data ID is handled implicitly (in the CRC computation, not the header) and there is no explicit Length field (unlike Profile 4 or Profile 6). This intentional minimalism is what enables AUTOSAR E2E Profile 5 to be the best-fit profile for CAN FD and compact Ethernet payloads where every byte matters.

Header Overhead Analysis Across Message Lengths

Total Payload	Signal Data	Profile 5 Overhead	Profile 4 Overhead	Profile 2 Overhead
8 bytes (classic CAN)	5 bytes	3/8 = 37.5%	N/A (too large)	2/8 = 25%
16 bytes	13 bytes	3/16 = 18.8%	12/16 = 75%	2/16 = 12.5%
32 bytes	29 bytes	3/32 = 9.4%	12/32 = 37.5%	N/A (max 30B)
64 bytes (CAN FD max)	61 bytes	3/64 = 4.7%	12/64 = 18.8%	N/A (max 30B)
100 bytes (Ethernet)	97 bytes	3/100 = 3%	12/100 = 12%	N/A (max 30B)
256 bytes (Ethernet)	253 bytes	3/256 = 1.2%	12/256 = 4.7%	N/A (max 30B)

This table clearly illustrates why AUTOSAR E2E Profile 5 is the optimal choice for CAN FD (64-byte) payloads: at 4.7% overhead, it is significantly more efficient than Profile 4 (18.8%) while providing far stronger CRC protection than Profile 1/2 for these longer messages.

6. Header Offset – Flexible Placement in AUTOSAR E2E Profile 5

One of the most practically useful features of AUTOSAR E2E Profile 5 is the configurable Offset parameter that controls where the 3-byte E2E header is placed within the data element. This flexibility distinguishes Profile 5 from Profile 2 (fixed position) and provides similar configurability to Profile 4’s offset parameter, but for a much lighter header.

Common Offset Configurations

Offset Value	Header Position	Use Case
0 bits (default)	Header starts at Byte 0 of data element	Standard new designs — header at the very beginning, signal data from Byte 3 onward
32 bits (4 bytes)	Header starts at Byte 4	SOME/IP-based Ethernet where the first 4 bytes contain a SOME/IP header or message ID
64 bits (8 bytes)	Header starts at Byte 8	PDUs with an 8-byte protocol header (e.g., UDP header portion) before the E2E domain
Custom (N×8 bits)	Header starts at Byte N	Legacy message layouts where specific bytes are pre-allocated for other purposes

/* Example: SOME/IP Ethernet PDU with Profile 5, Offset = 32 bits (4 bytes) */

PDU Layout:
  Byte[0]    = SOME/IP Message ID (byte 0)   ← Not in E2E CRC scope
  Byte[1]    = SOME/IP Message ID (byte 1)   ← Not in E2E CRC scope
  Byte[2]    = SOME/IP Length (byte 0)       ← Not in E2E CRC scope
  Byte[3]    = SOME/IP Length (byte 1)       ← Not in E2E CRC scope
  Byte[4]    = CRC-16 high byte              ← E2E Profile 5 header start
  Byte[5]    = CRC-16 low byte               ← E2E Profile 5 header
  Byte[6]    = Counter                       ← E2E Profile 5 header end
  Byte[7..N] = Signal data                   ← Protected by E2E CRC

CRC computation covers Bytes[4..N] + DataID bytes (not Bytes[0..3])

The offset mechanism makes AUTOSAR E2E Profile 5 particularly valuable in architectures where a pre-existing protocol header (SOME/IP, custom application header, or IPC header) occupies the first bytes of the PDU. By setting the appropriate offset, E2E protection can be retrofitted into these structures without disrupting the existing header format.

7. E2E Profile 5 CRC-16-CCITT Polynomial 0x1021 – Deep Dive

The E2E Profile 5 CRC-16 CCITT 0x1021 polynomial is one of the most widely used CRC algorithms in computing and telecommunications history. Understanding its mathematical properties and why it was chosen for AUTOSAR E2E Profile 5 is essential for engineers performing automotive functional safety ISO 26262 ASIL D E2E CRC16 residual error analysis.

The Polynomial in Detail

G(x) = x¹⁶ + x¹² + x⁵ + 1
Hexadecimal representation (without leading 1): 0x1021
Binary: 0001 0000 0010 0001
Full polynomial with leading bit: 0x11021
Also known as: CRC-16-CCITT, CRC-16/CCITT-FALSE, CRC-CCITT, ITU-T V.41
Start Value: 0xFFFF
XOR Output Value: 0x0000 (no output XOR)
Input Reflection: FALSE (MSB-first processing)
Output Reflection: FALSE
AUTOSAR CRC Library Function: Crc_CalculateCRC16(data, length, startValue, firstCall)
Check Value (CRC of 0x31..0x39): 0x29B1
Magic Check (data + CRC): 0x1D0F

Why CRC-16-CCITT for AUTOSAR E2E Profile 5?

The selection of the E2E Profile 5 CRC-16 CCITT 0x1021 polynomial was driven primarily by the “proven in use” requirement from the AUTOSAR safety requirements specification. CRC-16-CCITT has over four decades of deployment history across:

HDLC and PPP serial data link protocols (ITU-T)
Kermit and XMODEM file transfer protocols
SD card and MMC memory card interfaces
ISO 14443 contactless smart card standards
Industrial Modbus communication over serial lines
Numerous proprietary automotive in-house safety protocols

This extensive deployment history provides strong statistical evidence of the polynomial’s fault detection effectiveness across a wide range of message lengths and error patterns – precisely the kind of real-world validation that supports automotive functional safety ISO 26262 ASIL D E2E CRC16 safety arguments.

Hamming Distance Properties of CRC-16-CCITT

Message Length Range	Minimum Hamming Distance (HD)	Guaranteed Detection
≤ 32,751 bits (~4094 bytes)	HD=4	All single-bit, double-bit, and triple-bit errors; all odd-bit errors; all burst errors ≤ 16 bits
Specific short lengths	HD=5 or HD=6	Better coverage for very short messages
All lengths	HD=3 (minimum)	All single-bit and double-bit errors detected

For automotive functional safety ISO 26262 ASIL D E2E CRC16 analysis, HD=4 for messages up to ~4094 bytes means the E2E Profile 5 CRC-16 CCITT 0x1021 polynomial guarantees detection of all error patterns affecting up to 3 bits simultaneously in any message within this size range. The residual undetected error probability for random corruption beyond the HD guarantee is approximately 2⁻¹⁶ = 1/65,536 – significantly better than the 2⁻⁸ = 1/256 of 8-bit CRC profiles, though weaker than Profile 4’s 2⁻³² for the same message length range.

CRC-16-CCITT vs. Other 16-bit CRC Polynomials

CRC Type	Polynomial	Start/XOR	Used In	HD for Automotive Lengths
CRC-16-CCITT (CCITT-FALSE)	0x1021	0xFFFF / 0x0000	E2E Profile 5, 6, 22	HD=4 for ≤4094 bytes
CRC-16-IBM (CRC-16/ARC)	0x8005	0x0000 / 0x0000	USB, Modbus RTU	HD=4 (different range)
CRC-16-DNP	0x3D65	0x0000 / 0xFFFF	DNP3 industrial	HD=5 for short messages
FlexRay CRC-24	0x5D6DCB	0xFEDCBA / 0x000000	FlexRay hardware	N/A (hardware, different domain)

Independence from Hardware Bus CRCs

Per AUTOSAR SRS_E2E_08533, the E2E Profile 5 CRC-16 CCITT 0x1021 polynomial must be different from the CRC used by the underlying physical bus. This requirement is satisfied for both CAN FD and Ethernet:

CAN FD CRC-17 / CRC-21: Hardware CRC for short and long CAN FD frames respectively – completely different from CRC-16-CCITT
Ethernet IEEE 802.3 CRC-32: Hardware Ethernet frame checksum – polynomial 0x04C11DB7, completely different from 0x1021
CAN CRC-15: Classic CAN hardware checksum – also completely different from 0x1021

This independence ensures that the software E2E CRC-16 and hardware bus CRC provide two genuinely independent error detection layers – the fundamental requirement for AUTOSAR E2E Profile 5 CAN FD Ethernet protection to satisfy ISO 26262 communication safety requirements.

8. AUTOSAR E2E Profile 5 – 8-bit Sequence Counter

The 8-bit counter in AUTOSAR E2E Profile 5 (values 0x00–0xFF) mirrors the counter design of Profile 4. Located at Byte [Offset+2] of the data element, it increments by 1 with each transmission and wraps from 0xFF back to 0x00 continuously. Unlike Profile 1/2’s 4-bit counter (which reserves value 0xF as invalid), Profile 5’s 8-bit counter uses all 256 values – there is no reserved or invalid counter state.

Counter Fault Detection Capabilities

Fault	Delta (received – lastValid)	E2E Status
Normal reception	1	OK
1–N messages lost (within MaxDeltaCounter)	2 to MaxDeltaCounter	OKSOMELOST
Too many consecutive messages lost	> MaxDeltaCounter	WRONGSEQUENCE
Same message received twice	0	REPEATED
No new data from RTE	N/A	NONEWDATA
CRC mismatch (any cause)	Any	ERROR
First reception after init	N/A	INITIAL

The 8-bit counter’s 256-value range means it wraps every 256 transmissions. For a CAN FD signal transmitted at 5ms, the counter wraps every 1.28 seconds – providing much stronger sequence integrity than Profile 1/2’s 4-bit counter (wraps every 75ms at 5ms rate). For slow-rate configuration data at 1000ms, the Profile 5 counter wraps every 256 seconds (~4.3 minutes), providing excellent replay attack resistance.

9. Data ID – Implicit CRC Inclusion in AUTOSAR E2E Profile 5

The 16-bit Data ID in AUTOSAR E2E Profile 5 is handled implicitly – it is NOT transmitted in the 3-byte header but IS incorporated into the CRC computation. This implicit approach is the key design choice that keeps the E2E Profile 5 3-byte header at its minimum size while still providing masquerade detection.

How the Data ID is Incorporated

After computing the CRC over the header bytes (with CRC bytes zeroed) and all signal data bytes, two additional bytes representing the Data ID are appended to the CRC input stream:

/* CRC-16-CCITT computation sequence for AUTOSAR E2E Profile 5 */

/* Step 1: CRC over header + signal data */
uint16 crc = Crc_CalculateCRC16(
    &Data[Offset],               /* Start from header */
    (dataLengthBytes - Offset),  /* All bytes from header to end */
    0xFFFF,                      /* Start value */
    TRUE                         /* First call */
);

/* Step 2: Append DataID low byte to CRC computation */
uint8 dataID_low  = (uint8)(Config->DataID & 0xFF);
uint8 dataID_high = (uint8)((Config->DataID >> 8) & 0xFF);

crc = Crc_CalculateCRC16(&dataID_low,  1, crc, FALSE); /* Continue CRC */
crc = Crc_CalculateCRC16(&dataID_high, 1, crc, FALSE); /* Continue CRC */

/* Result: crc contains the final CRC-16-CCITT over header+data+DataID */
/* Write into Data[Offset] (high byte) and Data[Offset+1] (low byte) */
Data[Offset]   = (uint8)((crc >> 8) & 0xFF);  /* CRC high byte */
Data[Offset+1] = (uint8)( crc       & 0xFF);  /* CRC low byte */

Implicit vs. Explicit Data ID – Design Trade-off

By choosing implicit Data ID inclusion, AUTOSAR E2E Profile 5 saves 2 bytes of header space compared to Profile 4’s explicit Data ID field. The trade-off is reduced diagnostic transparency: unlike Profile 4 where the Data ID can be read directly from the bus trace, Profile 5’s Data ID is invisible on the bus. A bus analyzer cannot determine from the trace alone whether a CRC failure is due to data corruption or Data ID mismatch – both appear as CRC errors. For integration debugging, engineers must verify Data ID configuration consistency through code review or ECU configuration comparison rather than bus trace analysis.

10. E2E_P05Protect() – Complete Algorithm

The E2E_P05Protect() function is the sender-side API of AUTOSAR E2E Profile 5. It accepts a variable Length parameter (like Profile 4) to support variable-length data elements.

Function Signature

Std_ReturnType E2E_P05Protect(
    const E2E_P05ConfigType*   ConfigPtr,   /* [in]     Static configuration     */
    E2E_P05ProtectStateType*   StatePtr,    /* [in/out] Counter state             */
    uint8*                     DataPtr,     /* [in/out] Data buffer               */
    uint16                     Length       /* [in]     Total data length (bytes) */
);

E2E_P05Protect() Algorithm – Step by Step

Input validation: Check NULL pointers; verify Length within [MinDataLength/8, MaxDataLength/8] and ≥ (Offset/8 + 3)
Write Counter at Byte[Offset/8 + 2]:Data[Offset/8 + 2] = (uint8)(State->Counter & 0xFF);
Zero CRC bytes at Bytes[Offset/8] and [Offset/8 + 1]:Data[Offset/8] = 0x00U; Data[Offset/8 + 1] = 0x00U;
Compute CRC-16-CCITT over entire data element from Offset, then append DataID bytes:uint8 OffsetBytes = (uint8)(Config->Offset / 8U); uint16 crc; uint8 dataID_low = (uint8)(Config->DataID & 0xFFU); uint8 dataID_high = (uint8)((Config->DataID >> 8U) & 0xFFU); /* CRC over header (CRC=0) + all signal data */ crc = Crc_CalculateCRC16(&Data[OffsetBytes], Length – OffsetBytes, 0xFFFFU, TRUE); /* Append DataID to CRC computation */ crc = Crc_CalculateCRC16(&dataID_low, 1U, crc, FALSE); crc = Crc_CalculateCRC16(&dataID_high, 1U, crc, FALSE);
Write CRC-16 in Big Endian at Bytes[Offset/8] and [Offset/8+1]:Data[OffsetBytes] = (uint8)((crc >> 8U) & 0xFFU); /* High byte first */ Data[OffsetBytes + 1U] = (uint8)( crc & 0xFFU); /* Low byte second */
Increment Counter (wraps 255→0):State->Counter = (State->Counter == 0xFFU) ? 0x00U : (State->Counter + 1U);
Return E2E_E_OK

Complete E2E_P05Protect() C Implementation Example

/* AUTOSAR E2E Profile 5 Protect - Complete C Implementation */
Std_ReturnType E2E_P05Protect(
    const E2E_P05ConfigType  *Config,
    E2E_P05ProtectStateType  *State,
    uint8                    *Data,
    uint16                    Length)
{
    uint8  offsetBytes;
    uint16 crc;
    uint8  dataID_low, dataID_high;

    /* Input validation */
    if ((Config == NULL_PTR) || (State == NULL_PTR) || (Data == NULL_PTR)) {
        return E2E_E_INPUTERR_NULL;
    }

    offsetBytes = (uint8)(Config->Offset / 8U);

    if ((Length < (Config->MinDataLength / 8U)) ||
        (Length > (Config->MaxDataLength / 8U)) ||
        (Length < (uint16)(offsetBytes + 3U))) {
        return E2E_E_INPUTERR_WRONG;
    }

    /* Write Counter into Byte[Offset+2] */
    Data[offsetBytes + 2U] = State->Counter;

    /* Zero CRC bytes for computation */
    Data[offsetBytes]      = 0x00U;
    Data[offsetBytes + 1U] = 0x00U;

    /* Prepare DataID bytes (low byte first, then high byte in computation) */
    dataID_low  = (uint8)(Config->DataID & 0xFFU);
    dataID_high = (uint8)((Config->DataID >> 8U) & 0xFFU);

    /* CRC-16-CCITT over data from Offset to end, then DataID bytes */
    crc = Crc_CalculateCRC16(&Data[offsetBytes],
                              (uint32)(Length - offsetBytes),
                              0xFFFFU,
                              TRUE);
    crc = Crc_CalculateCRC16(&dataID_low,  1U, crc, FALSE);
    crc = Crc_CalculateCRC16(&dataID_high, 1U, crc, FALSE);

    /* Write CRC-16 in Big Endian order */
    Data[offsetBytes]      = (uint8)((crc >> 8U) & 0xFFU);
    Data[offsetBytes + 1U] = (uint8)( crc         & 0xFFU);

    /* Increment counter, wrap 255 → 0 */
    State->Counter = (State->Counter == 0xFFU) ? 0x00U : (State->Counter + 1U);

    return E2E_E_OK;
}

11. E2E_P05Check() – Complete Algorithm

The receiver-side E2E_P05Check() function for AUTOSAR E2E Profile 5 verifies CRC, counter delta, and (indirectly through CRC) the Data ID. Unlike Profile 4, there is no explicit Length or DataID field comparison — all non-CRC header fields validate through the CRC computation itself.

Function Signature

Std_ReturnType E2E_P05Check(
    const E2E_P05ConfigType*  ConfigPtr,
    E2E_P05CheckStateType*    StatePtr,
    const uint8*              DataPtr,
    uint16                    Length
);

E2E_P05Check() Algorithm Steps

Input validation (NULL checks, Length range validation)
Check NewDataAvailable – if FALSE, set NONEWDATA status and update state machine
Read received Counter: uint8 recvCounter = Data[Offset/8 + 2];
Read received CRC:uint16 recvCRC = ((uint16)Data[Offset/8] << 8) | Data[Offset/8 + 1];
Recompute CRC: Zero CRC bytes in local computation buffer, compute CRC-16-CCITT over header+data+DataID bytes (same as protect), compare with recvCRC
- Mismatch → ERROR flag (corruption or masquerade or wrong DataID)
Evaluate Counter Delta:uint8 delta = (uint8)((recvCounter – State->LastValidCounter + 256U) % 256U);
- delta == 0 → REPEATED
- delta == 1 → OK
- 1 < delta ≤ MaxDeltaCounter → OKSOMELOST
- delta > MaxDeltaCounter → WRONGSEQUENCE
Update State Machine and LastValidCounter
Return E2E_E_OK (result in StatePtr->Status)

Complete Receiver SW-C Handling Example – CAN FD BMS Signal

/* AUTOSAR E2E Profile 5 receiver handling for CAN FD BMS cell data */
void BMS_ReceiveCellVoltageData(void)
{
    BMSCellVoltageType rxData;
    uint16 rxLength = sizeof(BMSCellVoltageType);  /* Fixed-length CAN FD frame */
    Std_ReturnType e2eRet;

    /* Read from RTE (CAN FD frame, 48 bytes total) */
    Rte_Read_BMSCellVoltage_Port((uint8*)&rxData);

    /* Run AUTOSAR E2E Profile 5 check */
    e2eRet = E2E_P05Check(
        &E2E_P05_Config_CellVoltage,
        &E2E_P05_CheckState_CellVoltage,
        (const uint8*)&rxData,
        rxLength
    );

    /* Process E2E check result */
    switch (E2E_P05_CheckState_CellVoltage.Status)
    {
        case E2E_P05STATUS_OK:
            /* CRC-16-CCITT verified, counter +1, DataID correct */
            BMS_ProcessCellVoltages(&rxData);
            break;

        case E2E_P05STATUS_OKSOMELOST:
            /* Data valid but 1–N CAN FD frames were lost */
            BMS_ProcessCellVoltages(&rxData);
            BMS_LogCommunicationEvent(BMS_EVENT_FRAMES_LOST);
            Dem_ReportErrorStatus(BMS_E2E_SomeLostDEM, DEM_EVENT_STATUS_FAILED);
            break;

        case E2E_P05STATUS_INITIAL:
            /* BMS just powered up — hold safe default */
            BMS_ApplySafeDefaultVoltage();
            break;

        case E2E_P05STATUS_REPEATED:
            /* CAN FD frame retransmission or gateway replay */
            BMS_ApplySafeDefaultVoltage();
            Dem_ReportErrorStatus(BMS_E2E_RepeatedDEM, DEM_EVENT_STATUS_FAILED);
            break;

        case E2E_P05STATUS_WRONGSEQUENCE:
        case E2E_P05STATUS_ERROR:
        default:
            /* CRC failure (corruption or DataID mismatch) or sequence jump */
            BMS_ApplySafeDefaultVoltage();
            Dem_ReportErrorStatus(BMS_E2E_CriticalDEM, DEM_EVENT_STATUS_FAILED);
            BMS_TriggerSafetyShutdownProtocol();
            break;
    }
}

12. AUTOSAR E2E Profile 5 State Machine

AUTOSAR E2E Profile 5 uses the standard AUTOSAR E2E shared state machine – the same three-state (INIT → VALID ↔ INVALID) architecture used across all profiles. The state machine provides hysteretic fault detection: requiring multiple consecutive errors to transition to INVALID, and multiple consecutive OK receptions to recover to VALID.

State	Meaning	Data Usable?	Transition Conditions
INIT	After `E2E_P05CheckInit()`. No reliable history. Awaiting first valid sequence.	❌ No	→ VALID: MinOkStateInit consecutive OK → INVALID: MaxErrorStateInit consecutive errors
VALID	Communication healthy. CRC-16-CCITT checks, counter sequence, DataID all consistent.	✅ Yes	→ INVALID: MaxErrorStateValid consecutive errors
INVALID	Communication degraded. Safety function MUST use safe default.	❌ No	→ VALID: MinOkStateInvalid consecutive OK

State Machine Configuration for CAN FD Safety Signals (ASIL D, 5ms)

/* Profile 5 state machine thresholds for 5ms CAN FD ASIL D signal */
MaxDeltaCounterInit  = 1U;   /* INIT: expect counter+1 */
MaxDeltaCounter      = 1U;   /* VALID/INVALID: 5ms rate, expect exactly +1 */
MinOkStateInit       = 3U;   /* 3×5ms = 15ms before declaring VALID from INIT */
MaxErrorStateInit    = 3U;   /* 3 errors in INIT → INVALID (safety-first) */
MinOkStateValid      = 1U;   /* 1 OK is enough to maintain VALID */
MaxErrorStateValid   = 3U;   /* 3×5ms = 15ms reaction time to detect fault */
MinOkStateInvalid    = 5U;   /* 5×5ms = 25ms recovery period (conservative) */
MaxErrorStateInvalid = 0U;   /* Stay INVALID; errors don't extend INVALID */

13. E2E_P05ConfigType – All Parameters Explained

typedef struct {

    uint16  DataID;           /* 16-bit unique identifier for this data element.
                                 NOT transmitted in header - implicit in CRC only.
                                 Incorporated as: CRC over (data + DataID_low + DataID_high).
                                 Must be unique system-wide per sender-receiver pair.
                                 Must be identical on sender and all receivers. */

    uint16  Offset;           /* Bit offset of E2E header start within data element.
                                 Must be a multiple of 8 (byte-aligned).
                                 Default: 0 (header at start).
                                 Range: 0 to (MinDataLength - 24) bits.
                                 Configures where [CRC-H][CRC-L][Counter] appears. */

    uint32  MinDataLength;    /* Minimum allowed total data length in BITS.
                                 Must be ≥ (Offset + 24) bits (header end minimum).
                                 For fixed-length: MinDataLength == MaxDataLength. */

    uint32  MaxDataLength;    /* Maximum allowed total data length in BITS.
                                 Maximum: 32768 bits (4096 bytes).
                                 For fixed-length: same as MinDataLength. */

    uint8   MaxDeltaCounterInit;   /* Max counter delta in INIT state */
    uint8   MaxDeltaCounter;       /* Max counter delta in VALID/INVALID state */
    uint8   MinOkStateInit;        /* OK receptions to exit INIT → VALID */
    uint8   MaxErrorStateInit;     /* Errors in INIT to enter INVALID */
    uint8   MinOkStateValid;       /* OK receptions to stay VALID (typically 1) */
    uint8   MaxErrorStateValid;    /* Consecutive errors in VALID → INVALID */
    uint8   MinOkStateInvalid;     /* OK receptions to recover INVALID → VALID */
    uint8   MaxErrorStateInvalid;  /* Errors in INVALID (0 = stay INVALID) */

} E2E_P05ConfigType;

Example Configuration – CAN FD BMS Cell Voltage (ASIL D, 5ms, 48 bytes)

/* Profile 5 config for BMS cell voltage CAN FD signal */
static const E2E_P05ConfigType E2E_P05_Config_CellVoltage = {
    .DataID              = 0x3C7FU,  /* OEM-assigned unique ID for cell voltage PDU */
    .Offset              = 0U,       /* Header at start of CAN FD payload */
    .MinDataLength       = 384U,     /* 48 bytes × 8 = 384 bits (fixed length) */
    .MaxDataLength       = 384U,     /* Fixed-length CAN FD frame */
    .MaxDeltaCounterInit = 1U,
    .MaxDeltaCounter     = 1U,       /* 5ms rate, expect +1 per cycle */
    .MinOkStateInit      = 3U,
    .MaxErrorStateInit   = 3U,
    .MinOkStateValid     = 1U,
    .MaxErrorStateValid  = 3U,
    .MinOkStateInvalid   = 5U,
    .MaxErrorStateInvalid= 0U,
};

14. E2E_P05CheckStatusType – Status Codes and Application Handling

Status Code	Hex	Meaning	Application Action
`E2E_P05STATUS_OK`	0x00	CRC-16-CCITT matched, DataID correct (via CRC), counter delta = 1.	✅ Use data normally
`E2E_P05STATUS_NONEWDATA`	0x01	No new data available. Receiver called faster than sender, or timeout pending.	⚠️ Apply safe default if timeout exceeded
`E2E_P05STATUS_WRONGSEQUENCE`	0x02	CRC OK but counter delta exceeded MaxDeltaCounter (too many frames lost).	⚠️ Apply safe default; log DTC
`E2E_P05STATUS_ERROR`	0x03	CRC-16-CCITT mismatch. Covers: data corruption, wrong DataID (masquerade), counter byte corruption.	❌ Discard; safe default; DTC; trigger safety reaction
`E2E_P05STATUS_REPEATED`	0x08	CRC OK but counter unchanged (frame replayed or repeated by gateway).	⚠️ Discard as stale; log repetition DTC
`E2E_P05STATUS_OKSOMELOST`	0x20	CRC OK and counter delta between 2 and MaxDeltaCounter. Some frames lost.	⚠️ Use data; log frame-loss DTC
`E2E_P05STATUS_INITIAL`	0x40	State machine in INIT — first reception after `E2E_P05CheckInit()`.	⚠️ Do not use data yet

15. Practical Implementation Guide for AUTOSAR E2E Profile 5

Implementing AUTOSAR E2E Profile 5 in a production project follows a similar workflow to other profiles, with a few Profile 5-specific considerations.

Step 1 – Enable CRC-16 in the Crc Module

In your AUTOSAR BSW configuration tool, navigate to the Crc module and enable CrcCrc16. The function Crc_CalculateCRC16() implements CRC-16-CCITT (0x1021). If your ECU also uses Profile 1/2, Crc_CalculateCRC8() and Crc_CalculateCRC8H2F() must also be enabled – they are separate enablement items. Note that Crc_CalculateCRC16() is also used by Profile 6 and Profile 22, so it is enabled automatically if any of these profiles are used.

Step 2 – Determine Offset and Data ID

For standard CAN FD PDUs with no pre-existing header: set Offset = 0. For SOME/IP Ethernet PDUs: determine how many bytes the SOME/IP header occupies and set Offset accordingly (typically 32 or 64 bits). Assign a unique 16-bit Data ID for each protected data element — document it in the communication matrix and ensure it matches exactly on sender and receiver. The implicit Data ID cannot be verified from bus traces, so configuration alignment must be validated during ECU integration testing.

Step 3 – Choose Fixed or Variable Length

For CAN FD signals with fixed frame size: set MinDataLength == MaxDataLength == (frameBytes × 8). For Ethernet messages with variable payloads: set MinDataLength to the minimum expected payload bytes × 8 and MaxDataLength to the maximum × 8. Note that unlike Profile 4 and Profile 6, AUTOSAR E2E Profile 5 does NOT include a Length field in the header — the receiver validates length only against the configured MinDataLength/MaxDataLength range, not against a transmitted length value.

Step 4 – Initialize State Structures

/* Initialize E2E Profile 5 states at system startup */
void SafetyCom_P05_Init(void)
{
    /* Sender side — counter starts at 0 */
    E2E_P05ProtectInit(&E2E_P05_ProtectState_CellVoltage);

    /* Receiver side — state machine starts in INIT */
    E2E_P05CheckInit(&E2E_P05_CheckState_CellVoltage);
}

Step 5 – Sender Integration

/* CAN FD sender task - 5ms cycle */
void BMS_TransmitCellVoltageCANFD(void)
{
    BMSCellVoltageType txFrame;
    uint16 frameLength = sizeof(BMSCellVoltageType);  /* e.g., 48 bytes */

    /* Fill signal data (starting at Byte 3, after 3-byte E2E header) */
    txFrame.CellVoltage[0] = BMS_ReadCell(0);
    txFrame.CellVoltage[1] = BMS_ReadCell(1);
    /* ... fill all cell voltages ... */

    /* Apply E2E Profile 5 protection — fills 3-byte header at Offset=0 */
    Std_ReturnType e2eRet = E2E_P05Protect(
        &E2E_P05_Config_CellVoltage,
        &E2E_P05_ProtectState_CellVoltage,
        (uint8*)&txFrame,
        frameLength
    );

    if (e2eRet == E2E_E_OK) {
        Rte_Write_BMSCellVoltage_Port((const uint8*)&txFrame);
    } else {
        Dem_ReportErrorStatus(BMS_E2E_InitError, DEM_EVENT_STATUS_FAILED);
    }
}

Step 6 – DataID Configuration Management

Since the Data ID in AUTOSAR E2E Profile 5 is implicit (never transmitted on the bus), a DataID mismatch between sender and receiver results in persistent CRC errors – but these errors look identical to data corruption errors from the bus trace perspective. The root cause cannot be determined from captured frames alone. Best practice is to include DataID verification as an explicit integration test at ECU bring-up: confirm that E2E checks produce E2E_P05STATUS_OK for known-valid messages before any other integration activities.

16. ISO 26262 Compliance and ASIL D Analysis for AUTOSAR E2E Profile 5

AUTOSAR E2E Profile 5 satisfies the communication protection requirements of automotive functional safety ISO 26262 ASIL D E2E CRC16 when correctly deployed and when a quantitative safety analysis demonstrates that the residual error probability meets the ASIL D requirement for the specific system.

Fault Coverage Summary

Fault Type	Detection Mechanism	Coverage Quality
Data corruption	CRC-16-CCITT (HD=4 for ≤4094 bytes)	High — detects all ≤3-bit errors; residual ~1/65536
Message loss	Counter delta (OKSOMELOST/WRONGSEQUENCE)	Near-zero
Message repetition	Counter delta = 0 (REPEATED)	Near-zero
Message delay/timeout	Counter freeze + NONEWDATA	Application-dependent threshold
Masquerade / wrong DataID	Implicit via CRC-16 (wrong DataID → CRC mismatch)	Moderate — 1/65536 probability of undetected masquerade
Wrong sequence	Counter delta > MaxDeltaCounter (WRONGSEQUENCE)	Near-zero
Message truncation	Partial — CRC will usually catch truncation, but no explicit Length field	Probabilistic (no independent Length check unlike Profile 4)

Key Limitation: No Explicit Length Field

An important distinction for automotive functional safety ISO 26262 ASIL D E2E CRC16 analysis: unlike Profile 4, AUTOSAR E2E Profile 5 does not include an explicit Length field in the header. Message truncation detection relies entirely on the CRC-16 — if truncation causes the CRC to still match (a low but non-zero probability event), the truncation will be undetected. For ASIL D safety cases where message truncation is a significant fault mode, Profile 4 (with its explicit Length field) or Profile 6 (which includes a Length field) may provide a stronger safety argument. For most CAN FD applications where the frame length is fixed by the CAN FD DLC field, truncation is essentially impossible at the physical layer, making the absence of a Length field acceptable.

Residual Error Comparison for ASIL D Argument

Profile	CRC Width	Residual Error Rate	ASIL D Suitability
Profile 1 / 2	8-bit	~2⁻⁸ = 1/256	Yes (for short CAN msgs)
Profile 5	16-bit	~2⁻¹⁶ = 1/65,536	Yes (better than 8-bit for medium-length)
Profile 4	32-bit	~2⁻³² = 1/4.3B	Yes (strongest for ≤4kB)
Profile 7	64-bit	~2⁻⁶⁴ (negligible)	Yes (best for large data)

17. Real-World Use Cases for AUTOSAR E2E Profile 5

AUTOSAR E2E Profile 5 finds its optimal deployment range in CAN FD and compact Ethernet applications where the 8-bit CRC profiles are insufficient but the 12-byte Profile 4 header is unnecessarily heavy.

Electric Vehicle Battery Management System (BMS) – CAN FD

Modern BMS controllers in electric vehicles typically communicate cell voltage, temperature, state-of-charge, and state-of-health data via CAN FD at rates of 10–100ms. A full cell measurement packet for a 96-cell battery pack can easily fill a 32–64 byte CAN FD frame. Profile 1/2 cannot protect these frames (30-byte maximum), while Profile 4’s 12-byte header wastes 19–37% of the payload. AUTOSAR E2E Profile 5 CAN FD Ethernet protection solves this perfectly: a 3-byte header on a 48-byte CAN FD frame represents only 6.3% overhead while providing 16-bit CRC protection sufficient for ASIL C–D BMS safety requirements.

Gateway ECU – CAN to CAN FD Protocol Conversion

In modern zonal architectures, gateway ECUs translate between classic CAN (with Profile 1/2 protection) and CAN FD. A gateway that aggregates multiple CAN signals into a single CAN FD PDU for forwarding to a domain controller must re-protect the aggregated data with a profile appropriate for CAN FD lengths. AUTOSAR E2E Profile 5 is the natural choice for these re-protected CAN FD output PDUs — maintaining ASIL D protection with minimal overhead on the longer CAN FD frame format.

Automotive Ethernet – Moderate-Length Safety PDUs

Ethernet-based ADAS and chassis control systems often exchange compact safety PDUs – 20–100 bytes – containing sensor status data, actuator commands, or diagnostic results. For these moderate-length Ethernet messages, AUTOSAR E2E Profile 5 CAN FD Ethernet protection offers an optimal balance: the 16-bit CRC provides significantly better fault coverage than 8-bit alternatives, while the 3-byte header is far less disruptive to Ethernet payload efficiency than Profile 4’s 12-byte header.

Intra-ECU Communication Between Software Partitions

Within high-performance SoCs running AUTOSAR Adaptive Platform, safety partitions exchange structured data elements through shared memory or IPC mechanisms. AUTOSAR E2E Profile 5 protects these intra-ECU data elements against software-induced corruption – buffer overflows, race conditions, or memory protection violations – that could corrupt the data in transit between ASIL D and QM software partitions. The configurable Offset allows the E2E header to be placed at any position within the shared data structure.

AUTOSAR Adaptive Platform – Service-Oriented Communication

In the AUTOSAR Adaptive Platform, AUTOSAR E2E Profile 5 can be applied to data element-oriented communication where Profiles 6, 7, or 22 (which are SOME/IP-specific) may be overspecified. For ara::com sender-receiver patterns with fixed-size data elements of moderate length, Profile 5 provides a clean, portable protection mechanism supported by both CP and AP.

18. AUTOSAR E2E Profile 5 vs Profile 2, Profile 4, Profile 6

Criterion	Profile 2	Profile 5	Profile 4	Profile 6
CRC Width	8-bit	16-bit	32-bit	16-bit
CRC Polynomial	CRC-8-H2F (0x2F)	CRC-16-CCITT (0x1021)	CRC-32-P4 (0xF4ACFB13)	CRC-16-CCITT (0x1021)
Header Size	2 bytes (fixed)	3 bytes (configurable offset)	12 bytes (configurable offset)	4 bytes (fixed)
Counter Width	4-bit (0–14)	8-bit (0–255)	8-bit (0–255)	8-bit (0–255)
Data ID	Rotating 8-bit list (implicit)	16-bit (implicit in CRC)	16-bit (explicit, transmitted)	16-bit (implicit in CRC)
Length Field	No	No	Yes (16-bit, explicit)	Yes (16-bit, explicit)
Max Data Length	256 bytes	4096 bytes	4096 bytes	4096 bytes
Variable Length	No	Yes (no explicit length check)	Yes (with explicit length check)	Yes (with explicit length check)
Primary Bus	CAN, FlexRay (CP only)	CAN FD, Ethernet (CP + AP)	FlexRay, Ethernet	Ethernet (SOME/IP)
Header Overhead (64B payload)	N/A (max 30B)	4.7%	18.8%	6.3%
Residual Error Rate	~1/256	~1/65,536	~1/4.3B	~1/65,536

Decision Guide

Choose AUTOSAR E2E Profile 5 when:

Data is 4–4096 bytes, bus is CAN FD or Ethernet
Minimum header overhead is critical (3 bytes vs Profile 4’s 12 bytes)
16-bit CRC protection is sufficient for the ASIL D safety argument
No explicit Length field in the header is acceptable (fixed-length or CRC-detectable truncation)
Both CP and AP platform support is needed

Choose Profile 6 instead of Profile 5 if:

The data uses SOME/IP serialization (Profile 6 is specifically designed for SOME/IP)
An explicit Length field for truncation detection is required (Profile 6 includes it; Profile 5 does not)

19. Advantages of AUTOSAR E2E Profile 5

1. Optimal Overhead-to-Protection Ratio for CAN FD: The E2E Profile 5 3-byte header adds only 4.7% overhead to a full 64-byte CAN FD frame – the best available trade-off between 8-bit CRC profiles (insufficient protection for 64-byte frames) and Profile 4 (18.8% overhead). For the CAN FD era, Profile 5 hits the design sweet spot.

2. Significantly Better CRC Coverage Than 8-bit Profiles: The E2E Profile 5 CRC-16 CCITT 0x1021 polynomial provides a residual error rate of ~1/65,536 – 256× better than 8-bit CRC profiles’ ~1/256. For ASIL D safety arguments at medium message lengths (20–256 bytes), this difference can be decisive in satisfying the quantitative PMHF budget without requiring the full overhead of Profile 4.

3. Configurable Offset for Protocol Stack Compatibility: The configurable Offset parameter makes AUTOSAR E2E Profile 5 adaptable to virtually any PDU structure – whether a plain CAN FD payload, a SOME/IP-wrapped Ethernet message, or a proprietary IPC structure. This flexibility eliminates the need to restructure existing message layouts to accommodate E2E protection.

4. Both CP and AP Platform Support: Unlike Profile 2 (CP only) or Profile 4 (primarily CP), AUTOSAR E2E Profile 5 is supported on both AUTOSAR Classic Platform and Adaptive Platform. Engineers building hybrid CP+AP architectures can use the same Profile 5 protection scheme on both sides, simplifying safety analysis and reducing the number of distinct E2E profile variants to certify.

5. Proven CRC-16-CCITT Polynomial: The decades-long deployment history of the E2E Profile 5 CRC-16 CCITT 0x1021 polynomial in telecommunications, storage, and industrial systems provides extensive field evidence for its fault detection effectiveness — directly supporting the “proven in use” safety argument required by ISO 26262 for ASIL D systems.

6. 8-bit Counter for Strong Sequence Protection: The 256-value counter wraps far less frequently than Profile 1/2’s 15-value counter. For slow-rate signals, configuration data, or status-only messages, the 8-bit counter provides significantly stronger protection against replay attacks and sequence jumps.

20. Limitations and Challenges of AUTOSAR E2E Profile 5

1. No Explicit Length Field – Truncation Detection Limitation: The E2E Profile 5 3-byte header does not include a Length field. Message truncation is detectable only through CRC failure – which is probabilistic (1/65,536 chance of undetected truncation for random data values). For applications where message truncation is a credible fault mode (e.g., protocol translation gateways, TCP reassembly), this limitation requires additional architectural measures or switching to Profile 6 (which includes an explicit Length field).

2. Implicit Data ID Cannot Be Verified from Bus Traces: Unlike Profile 4’s explicit DataID transmission, the AUTOSAR E2E Profile 5 DataID is never visible on the bus. A DataID configuration mismatch between sender and receiver appears identical to a data corruption error in bus traces – making root cause analysis more difficult during system integration. Extra care in DataID configuration management and explicit integration testing is required.

3. Weaker Masquerade Protection Than Profile 2’s DataIDList: Profile 2 uses a rotating 16-entry DataIDList that changes the effective message key with every transmission. Profile 5 uses a static 16-bit DataID that never changes. While still providing 1/65,536 masquerade detection probability (versus Profile 2’s equivalent probability), the static nature of Profile 5’s DataID means that once an attacker knows the DataID (e.g., through ECU reverse engineering), they can craft valid masquerade messages more easily than with Profile 2’s rotating key.

4. Weaker CRC Than Profile 4 for Long Messages: For messages in the 256–4096 byte range, Profile 4’s CRC-32 (residual ~1/4.3B) provides dramatically stronger protection than Profile 5’s CRC-16 (residual ~1/65,536). For applications at the upper end of Profile 5’s message length range where maximum ASIL D assurance is required, Profile 4 should be preferred despite its larger header overhead.

21. Testing and Fault Injection Strategy for AUTOSAR E2E Profile 5

Test ID	Fault Injected	Expected Status	Expected SW-C Reaction
TC-P5-001	Single bit flip in signal data byte (e.g., bit 5 of Byte 10)	E2E_P05STATUS_ERROR (CRC-16-CCITT mismatch)	Safe default; DTC
TC-P5-002	3-bit burst error across Bytes 15–16	E2E_P05STATUS_ERROR (HD=4 detects all ≤3-bit errors)	Safe default; DTC
TC-P5-003	Flip CRC high byte (Byte[Offset])	E2E_P05STATUS_ERROR	Safe default
TC-P5-004	Flip CRC low byte (Byte[Offset+1])	E2E_P05STATUS_ERROR	Safe default
TC-P5-005	Drop 1 CAN FD frame (1 message lost)	E2E_P05STATUS_OKSOMELOST (delta=2)	Use data; log some-lost DTC
TC-P5-006	Drop 3 consecutive CAN FD frames	E2E_P05STATUS_WRONGSEQUENCE (delta=4 > MaxDelta=1)	Safe default; DTC
TC-P5-007	Replay same frame twice (counter frozen)	E2E_P05STATUS_REPEATED	Discard stale; DTC
TC-P5-008	Sender stops (timeout beyond MaxDelta cycles)	E2E_P05STATUS_NONEWDATA	Safe default; timeout DTC
TC-P5-009	DataID misconfigured on receiver (simulate wrong DataID)	E2E_P05STATUS_ERROR (CRC mismatch — DataID change → CRC change)	Persistent ERROR → INVALID state
TC-P5-010	Counter rollback (send counter=5 after counter=10)	E2E_P05STATUS_WRONGSEQUENCE	Safe default; DTC
TC-P5-011	ECU reset mid-stream → INIT state	E2E_P05STATUS_INITIAL for first reception	Safe default until first OK
TC-P5-012	3+ errors → INVALID → 5 OK → VALID recovery	INVALID → VALID after MinOkStateInvalid=5 OK	Safe default during INVALID; normal after VALID
TC-P5-013	Big Endian byte-swap in CRC field (implementation bug)	E2E_P05STATUS_ERROR (CRC reads wrong value)	Persistent failure until fixed
TC-P5-014	Wrong Offset configured on receiver (e.g., 8 instead of 0)	E2E_P05STATUS_ERROR (reads wrong bytes as CRC/counter)	Persistent ERROR → INVALID

22. Tools and Configuration for AUTOSAR E2E Profile 5

Vector DaVinci Developer / Configurator Pro: Full AUTOSAR E2E Profile 5 support including DataID configuration, Offset selection, MinDataLength/MaxDataLength, state machine parameters, and E2E Transformer / Protection Wrapper code generation. CANoe with AUTOSAR E2E plugin can decode Profile 5 headers in CAN FD and Ethernet traces – displaying the 2-byte CRC and 1-byte counter at the configured Offset position. However, since DataID is implicit, CANoe cannot independently display the DataID in the trace.

ETAS RTA-CAR: Supports AUTOSAR E2E Profile 5 configuration in the BSW E2E module. Requires Crc16 enablement in the Crc module configuration. The RTA-Safe stack guide covers CAN FD PDU protection with Profile 5.

Elektrobit (EB) tresos Studio: Generates AUTOSAR-compliant E2E_P05ConfigType initialization and state structure handling code from GUI configuration. Suitable for production programs requiring toolchain-generated, certification-ready code.

dSPACE SCALEXIO / VEOS: Hardware-in-the-Loop support for AUTOSAR E2E Profile 5 fault injection testing on CAN FD and Ethernet networks. Supports automated execution of TC-P5-001 through TC-P5-014 test cases defined above.

Wireshark with AUTOSAR Dissectors: For Ethernet-based AUTOSAR E2E Profile 5 CAN FD Ethernet deployments, Wireshark can display the 3-byte E2E header at the configured Offset within UDP/Ethernet payloads – the 2-byte CRC and 1-byte counter are visible, though DataID is not shown (it is implicit). Useful for verifying counter increments and CRC field presence during integration debugging.

23. Frequently Asked Questions About AUTOSAR E2E Profile 5

Q1: What is the key difference between AUTOSAR E2E Profile 5 and Profile 6?

Both AUTOSAR E2E Profile 5 and Profile 6 use the same CRC-16-CCITT polynomial (0x1021) and 8-bit counter. The critical differences are: Profile 5 has a 3-byte header (no Length field, DataID implicit in CRC), while Profile 6 has a 4-byte header (explicit 16-bit Length field, DataID still implicit in CRC). Profile 6 was specifically designed for SOME/IP Ethernet communication and includes the Length field to detect message truncation in variable-length SOME/IP payloads. Profile 5 is more general-purpose and is better suited for CAN FD or applications where the Length field is not needed. Choose Profile 6 when SOME/IP compliance or explicit truncation detection is required; choose Profile 5 when minimum header overhead is the priority.

Q2: Can AUTOSAR E2E Profile 5 be used for classic CAN (8-byte payloads)?

Technically yes – AUTOSAR E2E Profile 5 has no minimum data length restriction that prevents 8-byte total payloads (Offset=0, 3-byte header + 5 bytes signal data). However, the 3-byte header represents 37.5% overhead for an 8-byte CAN frame, which is typically unacceptable. For classic CAN with 8-byte payloads, Profiles 1 or 2 (2-byte header, 25% overhead) are the appropriate choices. Profile 5 becomes the optimal choice when payloads exceed 12–16 bytes.

Q3: What CRC library function does AUTOSAR E2E Profile 5 use?

AUTOSAR E2E Profile 5 uses Crc_CalculateCRC16() from the AUTOSAR CRC Library (SWS_CRCLibrary). This function implements CRC-16-CCITT with polynomial 0x1021, start value 0xFFFF, XOR output value 0x0000, and no input/output bit reflection. The same function is also used by Profile 6 and Profile 22 – if any of these profiles are used in the same ECU, only a single enablement of CRC16 in the Crc module configuration is needed. Note that this is different from Crc_CalculateCRC16_CCITT() or any other 16-bit CRC variants – verify the correct function name in your toolchain-specific CRC module documentation.

Q4: How does AUTOSAR E2E Profile 5 handle variable-length data?

AUTOSAR E2E Profile 5 supports variable-length data through the MinDataLength and MaxDataLength configuration parameters. At each transmission, the sender passes the actual Length to E2E_P05Protect(); the receiver passes the actual received Length to E2E_P05Check(). The check function verifies that the Length falls within the configured range – but there is no explicit Length field in the header that the receiver can compare against. This means that if the same data arrives with a different length than was transmitted (truncation), detection depends entirely on the CRC-16 catching the missing bytes. For applications requiring guaranteed truncation detection, Profile 6 (with an explicit 16-bit Length field) is preferred.

Q5: Is AUTOSAR E2E Profile 5 available in Adaptive Platform?

Yes. Unlike Profile 2 (CP only), AUTOSAR E2E Profile 5 is supported in both AUTOSAR Classic Platform and Adaptive Platform. In the AP context, it can be applied to data element protection in ara::com sender-receiver patterns. For pure SOME/IP service-oriented communication in AP, Profiles 6, 7, and 22 are more commonly used, but Profile 5 remains a valid choice for fixed-length or non-SOME/IP data exchange where its lightweight 3-byte header is advantageous.

Q6: Why is CRC-16-CCITT (0x1021) used in three different E2E profiles (5, 6, and 22)?

Profiles 5, 6, and 22 all use CRC-16-CCITT (0x1021) because this polynomial provides the right protection strength for medium-length automotive messages while keeping the CRC field compact at 2 bytes. The profiles differ in header structure (3 bytes for Profile 5, 4 bytes for Profiles 6 and 22 due to the explicit Length field) and in their specific target use cases (CAN FD/generic for Profile 5, SOME/IP data elements for Profile 6, SOME/IP events for Profile 22). Using the same polynomial simplifies CRC library implementation (one function handles all three profiles) and enables code reuse across the profile implementations.

Q7: What happens if I configure a wrong Offset value on the receiver?

A misconfigured Offset on the receiver of AUTOSAR E2E Profile 5 causes it to read CRC and counter bytes from the wrong position in the data element. The recomputed CRC will be calculated over a different byte range than the sender used, and the CRC comparison will fail consistently. All received messages will report E2E_P05STATUS_ERROR, quickly driving the state machine to INVALID. The error pattern looks identical to persistent data corruption. Root cause investigation requires comparing the Offset configuration between sender and receiver ECU software – it is not diagnosable from bus traces alone. TC-P5-014 (Offset misconfiguration test) should be included in the integration test suite for this reason.

24. Conclusion

AUTOSAR E2E Profile 5 fills a strategically important gap in the AUTOSAR E2E library – providing a 16-bit CRC solution that is far superior to 8-bit CRC profiles for medium-length messages, while avoiding the 12-byte header weight of Profile 4. Its compact E2E Profile 5 3-byte header, flexible Offset parameter, and the proven E2E Profile 5 CRC-16 CCITT 0x1021 polynomial make it the natural first choice for AUTOSAR E2E Profile 5 CAN FD Ethernet protection in modern automotive embedded systems – whether protecting a 48-byte BMS cell voltage CAN FD frame, a 64-byte ADAS command PDU, or a 100-byte Ethernet safety message.

For engineers implementing automotive functional safety ISO 26262 ASIL D E2E CRC16 protection, Profile 5 offers a compelling combination: a residual error rate of ~1/65,536 (256× better than 8-bit CRC profiles), 8-bit counter protection (17× stronger sequence detection than 4-bit counters), CP and AP platform support, and a header overhead as low as 1.2% for 256-byte messages. Understanding its single key limitation – the absence of an explicit Length field – and the implications of its implicit Data ID handling are essential for making the correct architectural choice between Profile 5, Profile 4, and Profile 6 in any given safety-critical communication design.

📚 AUTOSAR E2E Profile Series – Continue Learning:

Discover more from PiEmbSysTech - Embedded Systems & VLSI Lab

Subscribe to get the latest posts sent to your email.

AUTOSAR E2E Profile 5 Explained: CRC-16 CCITT, 3-Byte Header, and CAN FD Ethernet Protection

Table of Contents

Table of Contents

1. What is AUTOSAR E2E Profile 5?

2. History and Background of AUTOSAR E2E Profile 5

3. AUTOSAR E2E Profile 5 in the AUTOSAR Architecture

4. AUTOSAR E2E Profile 5 – Complete Technical Specifications

5. The E2E Profile 5 3-Byte Header Layout – Bit-Level Detail

Why Only 3 Bytes?

Header Overhead Analysis Across Message Lengths

6. Header Offset – Flexible Placement in AUTOSAR E2E Profile 5

Common Offset Configurations

7. E2E Profile 5 CRC-16-CCITT Polynomial 0x1021 – Deep Dive

The Polynomial in Detail

Why CRC-16-CCITT for AUTOSAR E2E Profile 5?

Hamming Distance Properties of CRC-16-CCITT

CRC-16-CCITT vs. Other 16-bit CRC Polynomials

Independence from Hardware Bus CRCs

8. AUTOSAR E2E Profile 5 – 8-bit Sequence Counter

Counter Fault Detection Capabilities

9. Data ID – Implicit CRC Inclusion in AUTOSAR E2E Profile 5

How the Data ID is Incorporated

Implicit vs. Explicit Data ID – Design Trade-off

10. E2E_P05Protect() – Complete Algorithm

Function Signature

E2E_P05Protect() Algorithm – Step by Step

Complete E2E_P05Protect() C Implementation Example

11. E2E_P05Check() – Complete Algorithm

Function Signature

E2E_P05Check() Algorithm Steps

Complete Receiver SW-C Handling Example – CAN FD BMS Signal

12. AUTOSAR E2E Profile 5 State Machine

State Machine Configuration for CAN FD Safety Signals (ASIL D, 5ms)

13. E2E_P05ConfigType – All Parameters Explained

Example Configuration – CAN FD BMS Cell Voltage (ASIL D, 5ms, 48 bytes)

14. E2E_P05CheckStatusType – Status Codes and Application Handling

15. Practical Implementation Guide for AUTOSAR E2E Profile 5

Step 1 – Enable CRC-16 in the Crc Module

Step 2 – Determine Offset and Data ID

Step 3 – Choose Fixed or Variable Length

Step 4 – Initialize State Structures

Step 5 – Sender Integration

Step 6 – DataID Configuration Management

16. ISO 26262 Compliance and ASIL D Analysis for AUTOSAR E2E Profile 5

Fault Coverage Summary

Key Limitation: No Explicit Length Field

Residual Error Comparison for ASIL D Argument

17. Real-World Use Cases for AUTOSAR E2E Profile 5

Electric Vehicle Battery Management System (BMS) – CAN FD

Gateway ECU – CAN to CAN FD Protocol Conversion

Automotive Ethernet – Moderate-Length Safety PDUs

Intra-ECU Communication Between Software Partitions

AUTOSAR Adaptive Platform – Service-Oriented Communication

18. AUTOSAR E2E Profile 5 vs Profile 2, Profile 4, Profile 6

Decision Guide

19. Advantages of AUTOSAR E2E Profile 5

20. Limitations and Challenges of AUTOSAR E2E Profile 5

21. Testing and Fault Injection Strategy for AUTOSAR E2E Profile 5

22. Tools and Configuration for AUTOSAR E2E Profile 5

23. Frequently Asked Questions About AUTOSAR E2E Profile 5

24. Conclusion

Related

Discover more from PiEmbSysTech - Embedded Systems & VLSI Lab

Equivalent Technical Articles

Leave a ReplyCancel reply

fdhfghfgh

Discover more from PiEmbSysTech - Embedded Systems & VLSI Lab