topic Re: CAN wake up in S12 / MagniV Microcontrollers

CAN wake up

SCort_li — Mon, 25 Apr 2022 01:36:08 GMT

We use TJA1044 CAN Transceiver and S12Z chip for CAN bus wake-up experiment. According to the TJA1044 chip manual: WAKE-UP FILTER will filter out some level changes of CAN bus. After the wake-up event is triggered, Rx will reflect CAN The level of the bus changes. S12 cannot correctly receive the information contained in the CAN wake-up frame, because the wake-up event (dominant-recessive-dominant) is partially filtered out by the CAN Transceiver. In fact, S12 correctly receives all the information of the CAN wake-up frame. how about this? Our baud rate is 500kbit/s.Thanks for browsing this issue.

Re: CAN wake up

kef2 — Mon, 25 Apr 2022 07:38:31 GMT

In fact, S12 correctly receives all the information of the CAN wake-up frame

How many active nodes do you have on the bus? If just sender and sleeping S12, then sending node doesn't receive ack and resends message until some other node acks it. So try connecting additional non-sleeping node and see what happens to wake message.

Re: CAN wake up

SCort_li — Mon, 25 Apr 2022 10:39:44 GMT

Thank you very much,I have solved the problem.

I add an another active node in the CAN bus,the new node ack the wake-up frame,

the S12 is waken but doesn't receive the correct frame.

If there are only two node in the CAN bus，S12 will receive the content of wake-up frame.