I really would like to find out what's being said when messages are passed between the various links/control units in our cars. The main reason I would like to know is to effectively fake the battery full signal/message to the MCM so that full assist/soc is available at all times.
Any comments, looking through the archive here seems we know very little about the inter unit comms except the ones used for MIMA of course.
Anyone care to guess at the protocol being used for the BATTSCI1 & BATTSCI2 signals?
Even if we just end up capturing a full battery signal/message and then keep sending it out with a pic without even understanding it that would do at a pinch.
Here are a couple of scans from the manuals, which clearly mention a serial SOC (State of Charge) signal is being sent on connector pins (7) & (20) BATTSCI1 & BATTSCI2, these seem to have a pull up and pull down resistor shown, and Logic ground is also available. So thoughts? capture data between the two wires or referenced to ground and as two separate channels, is one transmit, other recieve? I suspect so.
Looks like page 389 onwards in datasheet 1 looks critical to our project. Describes the serial inteface
Also page 118 in datasheet 2 looks interesting, are all three modules, BCM, ECM, MCM using this system on same bus?
I'll have a look inside the other modules to see If they are the same cpu.
Interestingly the bcm & mcm I opened have a 10pin programming connector on the main board, now I had heard some could be updated with a special programmer/software. Anyone ever seen this?
Since there are 2 pins for each signal,, and they are both pulsed, perhaps they are RS485 as opposed to RS232, by using RS485 they would be less prone to corruption due to noise on the cables.
Since there are 2 pins for each signal,, and they are both pulsed, perhaps they are RS485 as opposed to RS232, by using RS485 they would be less prone to corruption due to noise on the cables.
malcolm
Malcolm
Care to explain the difference?
I'm sure one is txd and other is rxd. I haven't had time to study the serial comms section of the datasheet yet.
Here are some high res unresized pics of the innards of the three modules. I used macro mode with my cheapo compact camera but you can see quite a bit. All about 1mb
The Bcm & Mcm have the same cpu H8/538, the Ecm seems to have a different one.
Talk about complicated!!!! Where do I adjust the points then. LOL
All have a programming 10 pin connector?
Examining the data sheet I see the H8/538 has two seperate serial data channels, that explains the METSCI1 & METSCI2 connectors as well as the BATTSCI1 & BATTSCI2 ones I was looking at.
I might try seeing if the SCI pins on the cpu are connected to the pins on the plug to confirm this in next few days.
RS232 generally uses more pins and its use of a common ground limits distance and make it prone to interference. RS232 adds the ability for handshaking and the ability to stop/slow the flow of data if one side is not ready using RTS (ready to send) and CTS (clear to send) using a flow control protocol. RS232 is normally used in a point to point communications between two devices in a full duplex mode as multi-point was not defined in the protocol.
RS485 uses a more simple 2/3 wire implementation, it only defines electrical properties and not an overall protocol. It provides for support of greater distance and speed, and is less prone to interference. Voltages used are less and therfore the power requirements are lower. It is also used in multi-point comms (such as the three way comms you are talking about between the BCM, ECM, MCM) and is generally used in master -> slave(s) communication on a bus.
A good example of RS485 is the communication in a CCTV control room and the control unit that selects the cameras and sends the pan tilt zoom commands. All the cameras are listening to the same RS485 bus, but only action the commands to thier camera address. These signals running on simple cheap cables over kilometers.
Richard
__________________
Insight owner since 7th Feb 2009
2005 Silver Manual Insight with 25,000 miles. lmpg 81.9 Imperial.
2001 Black A2 1.4 TDI 87,000 miles, 2007 Silver A8 3.0 TDI 92,000 miles.
All my cars are Aluminum (I think its magnetism)
I've had a reply from the Logic hardware people who seem to think there unit will be suitable to capture/analyse this bcm/mcm/ecm serial data.
However I need to confirm the voltage of the signals which must be logic level 3.3 or 5v for the unit to work. I'll try and do that today.
I'm almost certain to buy one of these, and if anyone in UK wanted to contribute, then feel free to send me some money via paypal to peter@solarvan.gotadsl.co.uk.
Richard has already offered to help, and the unit will obviously be available in UK to those who contribute towards it.
Any data I glean will of course be shared on here.
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Analysing the BCM/MCM Signals
