In an operating vehicle there are several ECU’s (Electronic Control Unit) communicating with each other to make everything work as a complete. An ECU is a small embedded computer that has specific behaviour implemented in it to take care of certain parts of a vehicle. Engine, transmission, hydraulics, instrument and so on have their own ECU’s. Communication between these autonomous nodes that the ECU’s represent, make the use of network protocols a necessity. There are two main protocols in use to solve different communication needs.
First there is CAN (Controller Area Network) according to J1939 standard in use for most of the data communication. With CAN being the primary bus, it allows critical interchange at high speeds among the connected modules.
The second alternative in use is a protocol following the J1708/J1587 standard. A rather old standard, yet offering the advantages of proven by use, reliable but rather slow communication service, used mainly for secondary data exchange. J1708 is based on RS-485 electrical specifications and therefore benefits from the ruggedness, low cost and availability of compliant IC’s already on the market.
For my master thesis, I have developed an automotive data logger device. This device is capable of saving ECU’s communication in vehicles onto an SD card.
The first part of this thesis specifies the technologies used in the automotive industry with special attention to the CAN and the J1708/J1587 protocols. This is followed by the analysis of the market trends of 32 bit microcontrollers and Integrated Development Environments supported by ARM platform.
In the seventh chapter I describe how the inputs are interfaced with the embedded system.
The final part of my thesis reviews the methods of processing the logged data from the SD card and testing device functionality.