PurpleMeaniePosts related to ECU, OBD, ISOTP, CAN and Diagnostics
I can’t really blame anyone for this article. Even when I was writing up the ECU work on this blog, I had it in my mind that I’d be able to do a Lowflying article at some time. Then, when Michael Calvert asked members if they could write more articles for the magazine ( because […]
This is hopefully a reasonably short post about the software framework I’ve developed to help read sensor data from the MBE 9A4 ECU. The software is written in Python 3 and is available here: Caterham-OBD. However, I’m going to talk about using one file only which is mbe.py. The idea behind mbe.py is to “abstract” […]
SUMMARY We now understand the communications protocol used by Easimap (the Windows software supplied by the ECU manufacturer) and can use it to ask the ECU for whatever data the car has to offer. We can then manipulate the responses we get back from the car and format them to make sense to us. TL;DR […]
The OBD-II diagnostic protocol is well defined and information about it can be found in On-board Diagnostics. It’s a mish-mash of many diffrerent standards, both physical and electrical, that I’ll refer to as OBD-II. There’s also a complete breakdown of the Services and PIDs (see below) that can be found in On-board Diagnostic PIDs. I’ll talk […]
The simplest of the three Caterham OBD port diagnostic protocols we know about is what I’ve called MBE-Broadcast. As soon as the car is put into ignition switch position 2, the ECU starts to spit out a this stream of data on the CAN bus. Unlike the OBD-II protocol and the MBE-ISOTP protocol, this a […]