Method update_pin

libraries/AP_WheelEncoder/WheelEncoder_Quadrature.cpp:25–58

check if pin has changed and initialise gpio event callback

// check if pin has changed and initialise gpio event callback
void AP_WheelEncoder_Quadrature::update_pin(uint8_t &pin,
                                            uint8_t new_pin,
                                            uint8_t &pin_value)
{
    if (new_pin == pin) {
        // no change
        return;
    }

    // remove old gpio event callback if present
    if (pin != (uint8_t)-1 &&
        !hal.gpio->detach_interrupt(pin)) {
        GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "WEnc: Failed to detach from pin %u", pin);
        // ignore this failure or the user may be stuck
    }

    pin = new_pin;

    // install interrupt handler on rising or falling edge of gpio for pin a
    if (new_pin != (uint8_t)-1) {
        hal.gpio->pinMode(pin, HAL_GPIO_INPUT);
        if (!hal.gpio->attach_interrupt(
                pin,
                FUNCTOR_BIND_MEMBER(&AP_WheelEncoder_Quadrature::irq_handler,
                                    void,
                                    uint8_t,
                                    bool,
                                    uint32_t),
                AP_HAL::GPIO::INTERRUPT_BOTH)) {
            GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "WEnc: Failed to attach to pin %u", pin);
        }
        pin_value = hal.gpio->read(pin);
    }
}

void AP_WheelEncoder_Quadrature::update(void)
{