CAN bus receiving

[xrattiracer]

The new CAN broadcasting stuff is great, so easy to work with. There really isn't anything for receiving though, or at least it is very limited.
My current project will have gps and accelerometer data available, which i would like to send to the ms to be logged along with everything else, as well as using the gps module as a rtc. The current CAN receiving seems to be only for pwm and analog values, and a couple specific implementations for other data points. Are there any plans for extending the CAN receiving function to handle these other types of data?

[jsmcortina]

I'm glad to hear that the broadcasting is working out for you.

For the receiving, GPS, accelerometer and time are difficult to define in a generic manner. It might be better to define a message protocol for that datatype and have MS3 specifically listen for it. Jean's IO-x can provide that data too, so it could (perhaps) use the same messaging protocol.

James

[xrattiracer]

yeah i think for now i can send accelerometer as analog values, and try to figure out the jbperf format for the gps and clock. looking around here and jbperf forum for details on that now...

[racingmini_mtl]

The format is quite simple and you can find it in the IOx ini file. What is going to be more complex is that you're going to have to implement the Megasquirt CAN protocol so that the MS3 can poll the data from your device.

Jean

[jsmcortina]

Currently yes. In the future though we could define an 11bit broadcast message for that data and bypass the Megasquirt-CAN stuff.

James

[xrattiracer]

I am most likely not going to be able to implement the MS format, it is just too different from standard CAN to be able to use the existing teensy flexcan library as far as i can tell and my c++ isn't strong enough to go lower level than that. So I guess i will be stuck for now.

[jsmcortina]

For reference, the Megasquirt 29bit CAN protocol is documented here:
http://www.msextra.com/doc/pdf/Megasqui ... -10-28.pdf

James

[xrattiracer]

I've actually managed to make significant progress on this. Able to decode the 29 bit id into all its component values (unions are really, really cool!). The packets i am sending back dont seem to do anything though, i am probably either decoding the 3 data bytes from the MSG_REQ incorrectly or am sending back bad data.
If I have decoded things correctly, it is wanting 8 bytes, sent to table 14 offset 1178 for the clock. I am not otherwise able to find out if this is correct by looking in various ini files, can anyone else confirm this is correct? (running pre 1.4 alpha 6).

[xrattiracer]

had things a little bit backwards, it is working now at table 7 offset 589.

[jsmcortina]

That sounds more like it.

James