U must have forgot to initialize the can
interface. u can check if u initialized them with the following
command......
cat /sys/kernel/debug/pinctrl/44e10800.pinmux/pinmux-pins
OR this command
On Thursday, June 22, 2017 at 12:20:25 PM UTC+5:30, 官大天 wrote:
>
>
> <https://lh3.googleusercontent.com/-Xowo6dsQ8uk/WUtjgjYJmsI/AAAAAAAAAZc/hFPTgyv5f2INLpL7L9jlXxUedNpLmJ6wACLcBGAs/s1600/%25E7%2594%25B5%25E8%25B7%25AF1.png>
>
> <https://lh3.googleusercontent.com/-TQUmBQ2tJEw/WUtjYB3ZYDI/AAAAAAAAAZY/oEn8wrnXWdU8ifMJMB3DsXIsp76b6AYNQCLcBGAs/s1600/%25E7%2594%25B5%25E8%25B7%25AF.png>
>
> I use a TJA1050 module to expand My beaglebone black.The two picture up is
> my circuit. I use two resistors（10K and 4.7K） to convert 5V to 3.3V.
>
> Now，the problem is that when I set can0 up , It could only run on lookback
> mode, I can get CAN message use (candump can0). It doesn't work on other
> mode. I can get nothing.
>
> I work with this reference (
> https://docs.google.com/document/d/1sgurQ-7gLyn7g-Kg983NRM0aDkYEqHqy9dmrieX_RUM/edit#
> )
>
>
> DCAN1_RX
>
> P9_24
>
> serial in from CAN bus
>
> -27 - +40V common-mode voltage on bus
>
> DCAN1_TX
>
> P9_26
>
> serial out to CAN bus
>
> 3V max driver differential output voltage
> pin used.
> I use USB-CAN adapter to test.
>
>
> <https://lh3.googleusercontent.com/-sXcnPTJMaOI/WUtmvqYfCaI/AAAAAAAAAZo/SqeukMAuQ-4GgI9RPSfMRIZsJE6YcnACACLcBGAs/s1600/wave.png>
>
> I get this from DCAN1_RX pin. So I think the wiring of CAN bus is fine.
>
>
> I think there is noly two possibilities. Frist there is some thing wrong
> with my work. And The second , My BBB is broken.
>
> There is more info below.
>
>
>
>
> debian@beaglebone:~$ sudo ip link set can0 type can bitrate 50000 loopback
> on
> debian@beaglebone:~$ ip -details link show can0
> 5: can0: <NOARP,ECHO> mtu 16 qdisc pfifo_fast state DOWN mode DEFAULT
> group default qlen 10
> link/can promiscuity 0
> can <LOOPBACK> state STOPPED (berr-counter tx 0 rx 0) restart-ms 0
> bitrate 50000 sample-point 0.875
> tq 1250 prop-seg 6 phase-seg1 7 phase-seg2 2 sjw 1
> c_can: tseg1 2..16 tseg2 1..8 sjw 1..4 brp 1..1024 brp-inc 1
> clock 24000000
> debian@beaglebone:~$ sudo ifconfig can0 up
> debian@beaglebone:~$ ip -details link show can0
> 5: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UNKNOWN
> mode DEFAULT group default qlen 10
> link/can promiscuity 0
> can <LOOPBACK> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms
> 0
> bitrate 50000 sample-point 0.875
> tq 1250 prop-seg 6 phase-seg1 7 phase-seg2 2 sjw 1
> c_can: tseg1 2..16 tseg2 1..8 sjw 1..4 brp 1..1024 brp-inc 1
> clock 24000000
>
> debian@beaglebone:~$ candump can0
> can0 123 [8] 00 01 02 03 04 05 06 07
> can0 123 [8] 00 01 02 03 04 05 06 07
> can0 123 [8] 00 01 02 03 04 05 06 08
> can0 123 [8] 00 01 02 03 04 05 06 08
> debian@beaglebone:~$ ifconfig
> can0 Link encap:UNSPEC HWaddr
> 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
> UP RUNNING NOARP MTU:16 Metric:1
> RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:10
> RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
> Interrupt:208
>
>
>
--
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