Application Of UDS: ECU Flash Programming

The purpose of this module is to show the process and items that could be used in terms of data transfer between a client and a server, as suggested by UDS. One of the uses of UDS is the ECU flashing, typically to load a new version of an application program with fix or enhancements.

There are different methods available to flash the ECU in any automotive vehicle. In current edge technology, there are different types of communication protocols. To communicate any external diagnostic tool for ECU flashing, you need to use it. It is nothing like that you will flash the ECU only by using a communication protocol, you need to use any diagnostic protocol for ECU flashing. This combination standard makes another standard protocol to which you need to use any kind of vehicle work from flashing to diagnostic. The CAN and UDS protocol are among them making the automotive vehicles smart for any kind of vehicle service work.

The application of UDS in ECU flash programming is a mainframe in the automotive vehicle system. Before the UDS protocol, the automotive industry was supposed to use the KWP-2000 protocol. But due to certain limitations, they have developed a new standard ISO14229 called UDS protocol. So this diagnostic protocol is now implemented in most of the vehicles over the different communication protocols. The CAN protocol is one of them. The combination of both again creates a new standard called UDSonCan protocol.

The main job of UDS in such operation would be:

• To set the server into a reprogramming session mode.
• To start a reprogramming sequence.
• To handle the start and stop of data transfer.
• To handle the size and right order of both the data blocks being sent/received and the memory blocks where such data blocks should be stored.
• To allow the client to start/stop a routine that runs on the server.
• To allow the client to request a software reset event on the server.

Despite the fact that AUTOSAR does not explicitly specify, and thus still does not fully support the process of flash re-programming as stated in AUTOSAR Specification of Flash Driver, the newest AUTOSAR version 4.0 has just included in the DCM the support of some crucial UDS services that can be applied for taking care of most of the reprogramming-related actions written above:

• ReadMemoryByAddress.
• WriteMemoryByAddress.
• Request download.
• RequestUpload.
• Transfer data.
• RequestTransferExit.
• Communication control.
• ResponseOnEvent.

It can be seen then that the AUTOSAR specification relies strongly on UDS to perform flash reprogramming.