[参考译文] DRA821U：我们发现了 CAN 接口进入总线关闭状态的问题、从而阻止了任何 CAN 数据发送或接收。

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https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1566382/dra821u-we-re-seeing-an-issue-where-the-can-interface-enters-a-bus-off-state-preventing-any-can-data-transmission-or-reception

器件型号：DRA821U

工具/软件：

你（们）好

我们看到 CAN 接口进入总线关闭状态时出现的问题、导致无法发送或接收任何 CAN 数据。

症状：上电后立即~100 总线关闭/分钟；以无确认为主导；TX 下降增加。

影响：通信停止；自动重启会暂时反复恢复。

SDK：9.1

测试板：定制板（非 EVM）

初始化 CAN 接口（比特率：500kbps）

ip link set dev can1 txqueuelen 1000
ip link set dev can1 type can bitrate 500000 sample-point 0.80 restart-ms 300
ip link set dev can1 up

Tx 压降和总线关闭

root@tgu:~# ip -d -s link show can1
23: can1: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/can  promiscuity 0 minmtu 0 maxmtu 0
    can state ERROR-PASSIVE (berr-counter tx 0 rx 127) restart-ms 300
          bitrate 500000 sample-point 0.800
          tq 12 prop-seg 63 phase-seg1 64 phase-seg2 32 sjw 1 brp 1
          m_can: tseg1 2..256 tseg2 2..128 sjw 1..128 brp 1..512 brp_inc 1
          m_can: dtseg1 1..32 dtseg2 1..16 dsjw 1..16 dbrp 1..32 dbrp_inc 1
          clock 80000000
          re-started bus-errors arbit-lost error-warn error-pass bus-off
          7          0          0          15         15         7         numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 parentbus platform parentdev 2701000.can
    RX:  bytes packets errors dropped  missed   mcast
             0       0      0       0       0       0
    TX:  bytes packets errors dropped carrier collsns
            50       8      0       7       0       0
root@tgu:~#

调试点

1、CAN 控制器:回送测试

root@tgu:~# ip link set dev can1 down
root@tgu:~# ip link set dev can1 type can bitrate 500000 sample-point 0.800 restart-ms 300 loopback on
root@tgu:~# ip link set dev can1 up
root@tgu:~# candump can1 &
[1] 17039
root@tgu:~# cansend can1 123#12345678
  can1  123   [4]  12 34 56 78
  can1  123   [4]  12 34 56 78
root@tgu:~#
root@tgu:~# ip -d -s link show can1
23: can1: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/can  promiscuity 0 minmtu 0 maxmtu 0
    can <LOOPBACK> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 300
          bitrate 500000 sample-point 0.800
          tq 12 prop-seg 63 phase-seg1 64 phase-seg2 32 sjw 1 brp 1
          m_can: tseg1 2..256 tseg2 2..128 sjw 1..128 brp 1..512 brp_inc 1
          m_can: dtseg1 1..32 dtseg2 1..16 dsjw 1..16 dbrp 1..32 dbrp_inc 1
          clock 80000000
          re-started bus-errors arbit-lost error-warn error-pass bus-off
          7          0          0          15         15         7         numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 parentbus platform parentdev 2701000.can
    RX:  bytes packets errors dropped  missed   mcast
             4       1      0       0       0       0
    TX:  bytes packets errors dropped carrier collsns
            58      10      0       7       0       0
root@tgu:~#

2. CAN 控制器<-> CAN 收发器（通过逻辑分析仪）