fix various issues

- overcurrent error during motor calibration (this is caused by
overshoot. For now we just ignore the current limit during motor
calibration as we did before)
- factor 2 error at encoder calibration
- set error flag if Motor::arm() is called while the brake resistor is
enabled but disarmed.
- only arm brake resistor if enabled
- auto-arm brake resistor on clear_errors()

Firmware/MotorControl/encoder.cpp

@@ -228,7 +228,7 @@ bool Encoder::run_offset_calibration() {
         axis_->open_loop_controller_.target_voltage_ = axis_->motor_.config_.motor_type != Motor::MOTOR_TYPE_GIMBAL ? 0.0f : axis_->motor_.config_.calibration_current;
         axis_->open_loop_controller_.target_vel_ = 0.0f;
         axis_->open_loop_controller_.total_distance_ = 0.0f;
-        axis_->open_loop_controller_.phase_ = wrap_pm_pi(0 - config_.calib_scan_distance / 2.0f);
+        axis_->open_loop_controller_.phase_ = axis_->open_loop_controller_.initial_phase_ = wrap_pm_pi(0 - config_.calib_scan_distance / 2.0f);
 
         axis_->motor_.current_control_.enable_current_control_src_ = (axis_->motor_.config_.motor_type != Motor::MOTOR_TYPE_GIMBAL);
         axis_->motor_.current_control_.Idq_setpoint_src_.connect_to(&axis_->open_loop_controller_.Idq_setpoint_);
@@ -324,9 +324,9 @@ bool Encoder::run_offset_calibration() {
 
     axis_->motor_.disarm();
 
-    config_.phase_offset = encvaluesum / (num_steps * 2);
-    int32_t residual = encvaluesum - ((int64_t)config_.phase_offset * (int64_t)(num_steps * 2));
-    config_.phase_offset_float = (float)residual / (float)(num_steps * 2) + 0.5f;  // add 0.5 to center-align state to phase
+    config_.phase_offset = encvaluesum / num_steps;
+    int32_t residual = encvaluesum - ((int64_t)config_.phase_offset * (int64_t)num_steps);
+    config_.phase_offset_float = (float)residual / (float)num_steps + 0.5f;  // add 0.5 to center-align state to phase
 
     is_ready_ = true;
     return true;

Firmware/MotorControl/low_level.cpp

@@ -76,6 +76,9 @@ bool brake_resistor_saturated = false;
 // @brief Arms the brake resistor
 void safety_critical_arm_brake_resistor() {
     CRITICAL_SECTION() {
+        for (size_t i = 0; i < AXIS_COUNT; ++i) {
+            axes[i].motor_.I_bus_ = 0.0f;
+        }
         brake_resistor_armed = true;
         htim2.Instance->CCR3 = 0;
         htim2.Instance->CCR4 = TIM_APB1_PERIOD_CLOCKS + 1;
@@ -164,7 +167,9 @@ void start_adc_pwm() {
     HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_3);
     HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_4);
 
-    safety_critical_arm_brake_resistor();
+    if (odrv.config_.enable_brake_resistor) {
+        safety_critical_arm_brake_resistor();
+    }
 }
 
 // @brief ADC1 measurements are written to this buffer by DMA

Firmware/MotorControl/main.cpp

@@ -161,6 +161,9 @@ void ODrive::clear_errors() {
         axis.error_ = Axis::ERROR_NONE;
     }
     error_ = ERROR_NONE;
+    if (odrv.config_.enable_brake_resistor) {
+        safety_critical_arm_brake_resistor();
+    }
 }
 
 extern "C" {

Firmware/MotorControl/motor.cpp

@@ -198,8 +198,10 @@ bool Motor::arm(PhaseControlLaw<3>* control_law) {
             control_law_->reset();
         }
 
-        if (brake_resistor_armed) {
+        if (!odrv.config_.enable_brake_resistor || brake_resistor_armed) {
             is_armed_ = true;
+        } else {
+            error_ |= Motor::ERROR_BRAKE_RESISTOR_DISARMED;
         }
     }
 
@@ -217,7 +219,7 @@ bool Motor::arm(PhaseControlLaw<3>* control_law) {
  */
 void Motor::apply_pwm_timings(uint16_t timings[3], bool tentative) {
     CRITICAL_SECTION() {
-        if (!brake_resistor_armed) {
+        if (odrv.config_.enable_brake_resistor && !brake_resistor_armed) {
             disarm_with_error(ERROR_BRAKE_RESISTOR_DISARMED);
         }
 
@@ -609,7 +611,10 @@ void Motor::current_meas_cb(uint32_t timestamp, std::optional<Iph_ABC_t> current
         float Inorm_sq = 2.0f / 3.0f * (SQ(current_meas_->phA)
                                       + SQ(current_meas_->phB)
                                       + SQ(current_meas_->phC));
-        if (Inorm_sq > SQ(Itrip)) {
+
+        // Hack: we disable the current check during motor calibration because
+        // it tends to briefly overshoot when the motor moves to align flux with I_alpha
+        if (Inorm_sq > SQ(Itrip) && (axis_->current_state_ != Axis::AXIS_STATE_MOTOR_CALIBRATION)) {
             disarm_with_error(ERROR_CURRENT_LIMIT_VIOLATION);
         }
     } else if (is_armed_) {

Firmware/MotorControl/open_loop_controller.cpp

@@ -5,7 +5,7 @@
 void OpenLoopController::update(uint32_t timestamp) {
     auto [prev_Id, prev_Iq] = Idq_setpoint_.get_previous().value_or(float2D{0.0f, 0.0f});
     auto [prev_Vd, prev_Vq] = Vdq_setpoint_.get_previous().value_or(float2D{0.0f, 0.0f});
-    float phase = phase_.get_previous().value_or(0.0f);
+    float phase = phase_.get_previous().value_or(initial_phase_);
     float phase_vel = phase_vel_.get_previous().value_or(0.0f);
 
     (void)prev_Iq; // unused

Firmware/MotorControl/open_loop_controller.hpp

@@ -18,6 +18,7 @@ public:
     float target_vel_ = 0.0f;
     float target_current_ = 0.0f;
     float target_voltage_ = 0.0f;
+    float initial_phase_ = 0.0f;
 
     // State/Outputs
     uint32_t timestamp_ = 0;