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CAN communication not working on preview 3 on UC5550


#1

I am using a UC5550 with the UCM dev board and recently upgraded to preview 3. Since upgrading I am unable to perform any CAN communications. On preview 2 the CAN communication was working fine (both send and receive). Any help would be appreciated.


#2

What did you use for bit timing? I know there are existing known issues around it.


#3

I am communicating with a device at 125 kbits. I had been using the following fine.
var propagation = 1;
var phase1 = 13;
var phase2 = 2;
var baudratePrescaler = 27;
var synchronizationJumpWidth = 1;
var useMultiBitSampling = false;

I noticed some different settings on git and tried them (see below) but did not work.
var propagation = 1;
var phase1 = 13;
var phase2 = 2;
var baudratePrescaler = 27;
var synchronizationJumpWidth = 1;
var useMultiBitSampling = false;


#4

Sorry. I orignally used this OK.
var propagation = 1;
var phase1 = 7;
var phase2 =8;
var baudratePrescaler = 27;
var synchronizationJumpWidth = 1;
var useMultiBitSampling = false;


#5

I just tested both of your settings and was able to communicate with a third party CAN tool at 125K.

Both settings have a baud rate of 125K, the only difference is the sample point. With (1,13,2,27,1) the sample point is at 87.5%, which allows more propagation time for a longer bus length. The sample point of the older settings (1,7,8,27,1) is at 50%.

Did you enable the CAN controller [canController.Enable();]? I believe this is a new feature in preview3.
.


#6

Yes, I was missing the .Enable(). Now things are back to working. Thanks for your help!


#7

Glad I could help. Same problem tripped me up too. Hope you didn’t spend too much time on it!