stm32: pyb.CAN.init(extframe=False) excludes all frames #5508

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1. JohnieBraaf commented on Jan 9, 2020

   

   JohnieBraaf

   on Jan 9, 2020

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   thnx @jimmo, see the details below:

   There apprears to be an issue in the CAN drivers which prevents receiving messages with non extended id's.

   As a test I'm using a pyboard-D to send data between the 2 CAN ports.
   This works fine when the can filter is set to extframe=True.
   can.init(mode=pyb.CAN.NORMAL, extframe=True, prescaler=4, sjw=1, bs1=7, bs2=1)

   However, when changed to False, there are no incoming frames detected.
   I can see the frames with a CAN bus analyzer, but the rx callback does not trigger.
   can.init(mode=pyb.CAN.NORMAL, extframe=False, prescaler=4, sjw=1, bs1=7, bs2=1

   ---

   I think I might have found where this goes wrong.

   I'm using CAN.MASK32 with a blank values like this:
   can.setfilter(bank=self.itf-1, mode=pyb.CAN.MASK32, fifo=self.itf-1, params=(0x0, 0x0))

   Now when I trace back the code, I come to pyb_can.c, where the filtermasks are set.
   They appear to be designed for extended identifier format judging from the high value 0x1FFFE000.

   micropython/ports/stm32/pyb_can.c

   Lines 710 to 713 in bfbd944

   	filter.FilterIdHigh = (mp_obj_get_int(params[0]) & 0x1FFFE000) >> 13;
   	filter.FilterIdLow = (((mp_obj_get_int(params[0]) & 0x00001FFF) << 3) | 4) | rtr_masks[0];
   	filter.FilterMaskIdHigh = (mp_obj_get_int(params[1]) & 0x1FFFE000 ) >> 13;
   	filter.FilterMaskIdLow = (((mp_obj_get_int(params[1]) & 0x00001FFF) << 3) | 4) | rtr_masks[1];

   Now when I change it to blank, I start receiving the packets.
   filter.FilterIdHigh = 0x0000; filter.FilterIdLow = 0x0000;
filter.FilterMaskIdHigh = 0x0000; filter.FilterMaskIdLow = 0x0000;

   I don't understand the bitwise operators that are applied in the original code, maybe someone can have a look at it.
2. dpgeorge

   added

   port-stm32

   on Jan 12, 2020
3. gooyle commented on Oct 15, 2020

   

   gooyle

   on Oct 15, 2020

   Last edited by gooyle

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   has it been fixed already?we met it again,firmware we used is pybv11-20200902-v1.13
4. JohnieBraaf commented on Oct 15, 2020

   

   JohnieBraaf

   on Oct 15, 2020

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   Don't think so. You will need to hack the workaround in yourself or even better attempt a proper fix. The workaround works in any case
5. gooyle commented on Oct 25, 2020

   

   gooyle

   on Oct 25, 2020

   Last edited by gooyle

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   thx，a new version lib works，no preblems appear till now
6. tannewt

   added a commit that references this issue on Oct 28, 2021

   Merge pull request micropython#5508 from dhalbert/arg-fixes

   ...

   e049db7
7. JohnieBraaf commented on Jan 24, 2022

   

   JohnieBraaf

   on Jan 24, 2022

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   While writing down the steps to reproduce and looking at the code I realized, I should have used MASK16 instead of MASK32.
   Sorry for the confusion. I managed to receive non-extended id messages on non fd interfaces with the following filter:
   can1.setfilter(bank=0, mode=pyb.CAN.MASK16, fifo=0, params=(0x0, 0x0, 0x0, 0x0))
8. JohnieBraaf commented on Jan 24, 2022

   

   JohnieBraaf

   on Jan 24, 2022

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   @jimmo this issue can be closed
9. dpgeorge

   closed this as completedon Jan 27, 2022