Analysing the BCM/MCM Signals

[Mike Dabrowski 2000]

Malcolm
The windows calculator has a scientific mode that includes octal,hex conversion (View menu)
Pretty sure that you are seeing the checksum bit.
In the noisy insight environment that would be pretty important for reliable serial communications.

[retepsnikrep]

Thanks to all, nice to know people are looking at the data.

I'll grab a full pos recal from 0 bars by pulling fuse on Monday.

It will look pretty much like the 4bars to 19 bars one I did inc in latest data.

I can't charge from 0 to full in the real sense as my car doesn't work like that now, almost all the energy in my pack now comes via grid charger, and that is not monitoried by BCM, in fact it throws an IMA error if I turn car on while charging.

Problem is we still do not know the structure of the data, unless someone on here has sussed it?

Start Bits? Data bits? How Many? Parity? Stop Bits?

Anyone want to break down what they think is a byte/packet of data.

I would like to concentrate on the BATT signals first.

You can grab screen shots with the logic software to illustrate your ideas.

[retepsnikrep]

Originally Posted by E27006

One request Peter, If you wire a switch tied to a voltage onto one of the unused channels, you could then mark an event which could be replayed on the simulator traces. Malcolm

Good idea I'll think about this, but I need a +5v supply from within the bcm to do this or a seperate 5v supply with common ground with logic ground, I don't want to bugger anything up.


A question to Cianmh, who are you? Do you own an Insight? Have you e-mailed me privately before? Can you update your profile please.

[retepsnikrep]

In helping to establish the protocol being used this info from the datasheet may be useful. The BCM and MCM also have RS485 chips on board which are being driven by these serial channels on the CPU.

Page 417 & 418 also look useful in the datasheet.

H8/538 CPU Section 14 Serial Communication Interface
14.1 Overview
The on-chip serial communication interface (SCI) Note the naming convention here that matches our BATTSCI & METSCI wires in manual. has two independent channels in the H8/538, and three independent channels in the H8/539. All channels are functionally identical. The SCI supports both asynchronous and clocked synchronous serial communication. It also has a multiprocessor communication function for serial communication among two or more processors. The H8/538 does not have SCI3.

14.1.1 Features
SCI features are listed below.
• Selection of asynchronous or synchronous mode

a. Asynchronous mode
The SCI can communicate with a UART (universal asynchronous receiver/transmitter),
ACIA (asynchronous communication interface adapter), or other chip that employs
standard asynchronous serial communication. It can also communicate with two or more
other processors using the multiprocessor communication function.

There are twelve selectable serial data communication formats.
— Data length: seven or eight bits
— Stop bit length: one or two bits
— Parity: even, odd, or none
— Multiprocessor bit: one or none
— Receive error detection: parity, overrun, and framing errors
— Break detection: by reading the RXD level directly when a framing error occurs

b. Clocked synchronous mode
Serial data communication is synchronized with a clock signal. The SCI can
communicate with other chips having a clocked synchronous communication function.
— Data length: eight bits
— Receive error detection: overrun errors
• Full duplex communication
The transmitting and receiving sections are independent, so the SCI can transmit and receive
simultaneously. Both sections use double buffering, so continuous data transfer is possible in
both the transmit and receive directions.
389
• Built-in baud rate generator with selectable bit rates
• Internal or external transmit/receive clock source: baud rate generator or SCK pin
• Four types of interrupts

Transmit-data-empty, transmit-end, receive-data-full, and receive-error interrupts are
requested independently. The transmit-data-empty and receive-data-full interrupts can be
served by the on-chip data transfer controller (DTC) to transfer data.
In the H8/539, SCI2 and SCI3 have the same interrupt vectors.

[Cianmh]

Hi Again,

working in Cranfield University and we have an insight to play with.
Was looking to access the byte data to record the data more accuratly over a drive cycle.

Have spoken to a guy who has done all this work but is reluctant to part with the data

I amaware that all various signals of interest are sent as one Byte followed a checksum

even if we crack the code, anyone have any ideas what software can actually "listen" to this and display it sensibly?

The decoding is not a trivial task, or so I am told.

I will keep proding for any info from this guy, but don't hold out too much hope.

cianmh

[retepsnikrep]

Originally Posted by Cianmh

Hi Again,

working in Cranfield University and we have an insight to play with.
Was looking to access the byte data to record the data more accuratly over a drive cycle.

Have spoken to a guy who has done all this work but is reluctant to part with the data

I amaware that all various signals of interest are sent as one Byte followed a checksum

even if we crack the code, anyone have any ideas what software can actually "listen" to this and display it sensibly?

The decoding is not a trivial task, or so I am told.

I will keep proding for any info from this guy, but don't hold out too much hope.

cianmh

Can we offer this person money? I might bung some in if it saves as lot of time.

We will have to write an application to display the data, but to be honest i'm not that intrersted in viewing it in real time so long as we know what it is. I just want to fake it to send out the battery SOC message from my own Pic device to the MCM and dash display.

My intention is to remove the BCM eventually from my car.

Do you have any further info to confirm it is one byte with checksum?

Thanks for your input. I'll try and capture some more data tomorrow.

[E27006]

Will he part with some very basic information?

i.e. format of each byte, 7or 8 data bits, parity/odd even or none, stop bits , one or two.

Also the checksum, is it a single byte or two bytes in length?



malcolm

[retepsnikrep]

Malcolm

If he can help with that we will be sorted.

[jonnyvtec]

Fascinating thread guys. Really enjoying using this forum so far

[IamIan]

I've been reading a bit about the SMBus...

I've read about Panasonic using SMBus communication standards for other battery systems like laptops and such... and we know Panasonic did the battery pack for the Insights.

It is also a standard that was started back in the mid 90's so it has been around long enough for the first designs of the Insight.

I admit ... I am an amateur at best when it comes to this side of things... so if I am missing something ... my apologies.

but , I figured it wouldn't hurt to throw it out there.