How to use 2 CANBus Shield v2's on single Arduino?

Cement · March 13, 2022, 8:26am

I have a project where i need to talk to two independent CAN networks on a single Arduino Mega R3. How do I configure two identical Seeed CANBus Shield v2’s so that I can address the two networks independently ?

I see there is some discussion which sounds like this is possible on the Seeed product page / Wiki but my Arduino knowledge is already being stretched … some example code would be amazing.

My current code can be seen here which does what I need for a PoC against a single CANBus network currently. Next step is to manipulate this so its send to a single CAN network only and some dummy data is sent to the second network via the additional shield.

github.com

david-morton/E46-CANBus-Cluster-Control/blob/master/src/main.cpp

/* This is a very basic program to drive the E46 gauge cluster via CAN. The hardware used
was a Arduino Mega 2560 r3 and Seeed CAN-Bus shield v2.

The scaling ratio of engine RPM to hex value of CAN payload is 
approximated in this program based on a linear formula worked out in Excel.
This is simply done to give the most accurate dial readout possible.

For reference the measured ratios at varios RPM's in my own car are as per the below:
1000 6.65
2000 6.59
3000 6.53
4000 6.48
5000 6.42
6000 6.37
7000 6.31

The fuel economy gauge only works when there is a speed input. Inputting a square wave of
410Hz and 50% duty cycle gives 60km/h. This signal is put into pin 19 on cluster connector
X11175 for testing purposes on the bench. This signal is usually provided by the ABS computer.

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Cement · March 14, 2022, 6:47am

I managed to get this sorted out and am happily running the two shields now

Code changes needed are here as well as cutting the link on the back of the shield and soldering the pad to dictate the use of pin 10 as SS/CS on one of the shields only.