Mbed OS6 CAN bus error handling

main.cpp

#include <mbed.h>
RawCAN can(CAN_RXD_pin, CAN_TXD_pin);
DigitalOut can_sleep(CAN_STANDBY_pin, 0);

int main() {
    can.frequency(250000);
    can.mode(CAN::Normal);

    uint8_t tderr_prev = 0;
    bool bus_state = true;

    while (1) {
        CANMessage msg;
        msg.id = 0;
        msg.id |= 6 << 26; // priority
        msg.id |= 0xFF00 << 8; // SPN
        msg.id |= 0xA0; // SA
        msg.len = 8;
        msg.type = CANData;
        msg.format = CANExtended;
        memset(msg.data, 0, 8);

        int test = can.write(msg);
        uint8_t tderr = can.tderror();
        printf("prev:%u, now: %u, stat: %i\n", tderr_prev, tderr, test);

        if (tderr > 127) {
            // 255 - 8 (maximum tderror count) - (each error is + 8 for counter)
            if (tderr > 247) {
                if (tderr == tderr_prev) {
                    printf("Bus Off\n");
                    can.reset();
                    can.frequency(250000);
                    can.mode(CAN::Normal);
                }

            } else {
                if (tderr >= tderr_prev) {
                    if (bus_state) {
                        bus_state = false;
                        printf("Error Passive\n");
                    }

                } else {
                    if (!bus_state) {
                        bus_state = true;
                        printf("Bus recovered\n");
                    }
                }
            }

        } else if (!bus_state) {
            bus_state = true;
            printf("Bus Active\n");
        }


        tderr_prev = tderr;

        ThisThread::sleep_for(1000ms);
    }
}