Analysing the BCM/MCM Signals

[retepsnikrep]

I've sent an e-mail today to a clever chap in UK re the BCM/MCM comms.

MarkLamond.co.uk - Homepage

I'm hoping I can persuade him to assist

If he agrees I'll perhaps trundle up to see him in due course.

Jim and I are also touting for help on the PGFI forum. Fingers crossed

Peter

[retepsnikrep]

I added an access point for the BCM BATTSCI1 & 2 & logic ground signals today, to have a look at the data.

I managed to snatch one pic of the data which seems very slow and repeats regulary about once a second. Looked like a couple of bytes at most.

SOC was 19 bars and signal starts as soon as ign turns on.

I could not get my recording scope to work today so could only snap the begining of the transmission on BATTSCI1 and logic ground.

Must get one of those analysers.

www.solarvan.co.uk/insight/BCMSignal.jpg

Doesn't look that hard to fake If I can work out baud rate etc.

Might be able to do it ultra cruedly if I can get a picture of the entire transmission by just switching a pic output pin high/low with some pauses in between! Check/adjust pic output on scope until it looks the same!!

LOL

[retepsnikrep]

I've ordered one of those usb plug in logic analysers should be with me in a about 7 days.

Thanks to one IC member who sent be a donation towards it.

The total cost was about £100 UK.

I can't wait to get hold of it and get it plugged in.

I feel the faking signals pic project comming on as well now!!!

I'll look at the BCM MetSCI1 & 2 signals as well in due course, I havent even looked at where they go on the wiring diagram yet, perhaps to the Instrument cluster.

So might be able to con the SOC gauge as well later

[jonnyvtec]

Mark Lamond is a great bloke!

He did the electronics conversion work to my S2000 cluster that I fitted to my DC2 Integra.

[retepsnikrep]

Got my new digital storage scope today might try and grab a pic of BCM data later.

Surfing for info found a few links.

openecu.org • View topic - Honda Reflashing

Diagnostic Tools and Software

https://techinfo.honda.com/rjanisis/RJAAI001_tools2.asp

Honda GNA

[E27006]

Looking at the digital camera shots of the PCBs, the jelly bean chips are marked 9942 etc.

This means they (the chips) were manufactured year 1999 week 42.

This is likely to have been one of the earliest modules consructed for our cars.

E27006

[TimH]

Hi ...

I'm a new insight owner (2000 MT) in Nova Scotia. I'm also an electrical engineer with similar thoughts regarding taking control of the IMA at this level.

Just a thought, but a very simple tool to look at the data on the serial bus is to use the laptop serial port. You might need a USB to serial device on a newer laptop which probably won't have RS-232. These standards are fairly forgiving of voltage levels and because the laptop is not grounded, it may not matter if the source is unbalanced RS-232 or balanced RS-422/485. (Although I'd be suprised if it wasn't 422 or 485).

Just a thought ...

[retepsnikrep]

Tim welcome on board. Yes I suspect serial of some sort, but need to analyse it and then see about faking it. Jump in and assist by all means. I suspect RS485 half duplex and I have been browsing extensive info on internet about this protocol.

An example RS485 transmission is below.

[retepsnikrep]

Looking at the BCM signal today it is def serial RS485, and looking at the BCM board I have found the two transceiver chips are Linear Tech 1487.

Datasheet below.

www.solarvan.co.uk/insight/1487fs.pdf

Now just got to capture and analyse it.

I'll order one of these chips so I can drive it with a picaxe and send some data on the rs485 bus.

Another useful device I've just ordered to play around with is.

http://www.robot-electronics.co.uk/h...rs485_tech.htm

[retepsnikrep]

Well I plumbed in the little RS485 transceiver into the BatSCI1 & BATSCI2 and logic grounds today and captured some BCM <> MCM comms data onto my laptop.

Problem is not knowing the baud rate/structure means it could all be garbage at the moment.

I tried various settings for the recieving software which was the demo version of

Data Logger. Advanced Serial Data Logger software - serial and RS232 port data collection and acquisition software | AGG Software

There was a fair bit of chat going on.

But I need to look at one packet/byte on my scope to see the structure and then set serial software accordingly.

Very neat little rs485/usb comms gadget should allow me to use my laptop to send test fake data to the mcm fairly easily.

www.solarvan.co.uk/insight/rs485gadget.jpg