Good morning,
I hope someone can give me some pointers on what might be causing my system an issue or how to debug the issue.
The revision 2 Waveshare Dual channel MCP251xFD CAN HAT was working fine in my LAB with 2 or 3 other can devices. Both can channels are using standard 29 bit CAN2.0 extended identifiers. The can0 interface was running at 250kb, and can1at 500Kb.
As soon as I moved the device into my live environment I have started to have issues.
The 250Kb segment has around 10-15 devices and a bus length of something in the order of 40m, properly terminated at each end with a 120ohm resistor. The 500kb segment has 2 devices and is maybe 10m in length and also properly terminated. Without the PI connected both segments are running fine with no reported BER counters. The following output is from an embedded linux based device on the network when my PI is not connected.
root@Venus:~# ip -details link show can0
3: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP mode DEFAULT group default qlen 100
link/can promiscuity 0 minmtu 0 maxmtu 0
can state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 100
bitrate 250000 sample-point 0.875
tq 250 prop-seg 6 phase-seg1 7 phase-seg2 2 sjw 1
sun4i_can: tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1
clock 24000000 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
The bus loading is very low.
root@Venus:~# canbusload can0@250000
can0@250000 84 13440 5376 5%
can0@250000 133 21280 8512 8%
can0@250000 95 15200 6080 6%
can0@250000 114 18240 7296 7%
can0@250000 105 16800 6720 6%
can0@250000 132 21020 8368 8%
can0@250000 104 16640 6656 6%
As soon as I attach the PI4 with the revision 2.1 waveshare 251xFD dual can hat I start getting BER errors on devices, and the PI is reporting RX BER errors.
The embedded Linux device
root@Venus:~# ip -details link show can0
3: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP mode DEFAULT group default qlen 100
link/can promiscuity 0 minmtu 0 maxmtu 0
can state ERROR-ACTIVE (berr-counter tx 0 rx 83) restart-ms 100
bitrate 250000 sample-point 0.875
tq 250 prop-seg 6 phase-seg1 7 phase-seg2 2 sjw 1
sun4i_can: tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1
clock 24000000 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
RaspberryPI4 with the wave share dual can hat
root@Olaso-PI:~# ip -details link show can0
5: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP mode DEFAULT group default qlen 100
link/can promiscuity 0 minmtu 0 maxmtu 0
can state ERROR-WARNING (berr-counter tx 0 rx 124) restart-ms 100
bitrate 250000 sample-point 0.875
tq 25 prop-seg 69 phase-seg1 70 phase-seg2 20 sjw 1
mcp251xfd: tseg1 2..256 tseg2 1..128 sjw 1..128 brp 1..256 brp-inc 1
mcp251xfd: dtseg1 1..32 dtseg2 1..16 dsjw 1..16 dbrp 1..256 dbrp-inc 1
clock 40000000 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
ip -details link show can1
6: can1: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP mode DEFAULT group default qlen 100
link/can promiscuity 0 minmtu 0 maxmtu 0
can state ERROR-WARNING (berr-counter tx 0 rx 125) restart-ms 100
bitrate 500000 sample-point 0.875
tq 25 prop-seg 34 phase-seg1 35 phase-seg2 10 sjw 1
mcp251xfd: tseg1 2..256 tseg2 1..128 sjw 1..128 brp 1..256 brp-inc 1
mcp251xfd: dtseg1 1..32 dtseg2 1..16 dsjw 1..16 dbrp 1..256 dbrp-inc 1
clock 40000000 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
Do you have any idea what might be doing this. I have checked cables, termination, voltages, etc and all are OK. I have asked Waveshare and basically been given the not our issue, its the network.
I have even checked the cable drops between the backbone and PI, by plugging alternative devices in and they have behaved correctly. Moving the PI to an alternative drop has also not hanged anything.
It seems to me that there might be a timing issue, but have no idea how to check.
Thank you.
Regards
Mark
