Tool/software:
Hi,
When testing CAN communication due to transmission error, a node entered a bus-off state. But on observing MCAN_ECR register, the TEC Value is observed to be 248. But as per the protocol, CAN node should enter a bus-off state only when the counter reaches the maximum value of 255. What could be the reason for the counter not reaching it's maximum value?
Thank you,
Rishitha
Hi Rishitha,
A CAN node enters bus-off state only when TEC>255. The Transmit Error Counter TEC is 8 bits wide, therefore it has a range from 0 to 255 (0x00 to 0xFF).
When the TEC is in the range from 248 to 255 and there is a further error condition that would requir an increment by 8, this increment would result in a value > 255, which would be an overflow (=carry) condition. So, in this case, instead of incrementing the TEC, only the Bus-Off flag is set.
