[SOFT-452] Regen braking toggling: MCI (#416)

Implemented the regen braking on MCI side by
 - Adding a regen braking state in regen_braking.c
 - Making test cases in test_regen_braking.c to ensure the functionality of regen_braking.c
 - Adding the internal regen_brake state to mci_output.c to set the current to zero when regen is diabled and the target velocity is less than the current velocity.
 - Added additional test cases to 'test_mci_output.c` to test all driving and pedal modes both when regen barking is enabled and disabled.

projects/mci/inc/mci_output.h

@@ -15,4 +15,6 @@ typedef struct {
   PedalRxStorage pedal_storage;
 } MotorControllerOutputStorage;
 
+void mci_output_update_velocity(float actual_velocity_ms);
+
 StatusCode mci_output_init(MotorControllerOutputStorage *storage, Mcp2515Storage *motor_can);

projects/mci/inc/regen_braking.h

@@ -0,0 +1,19 @@
+#pragma once
+
+// A module to set the regen braking state in MCI
+// upon receiving a CAN_TRANSMIT_REGEN_BRAKING can
+// message. The regen braking state is used in
+// mci_output.c which determines whether we are
+// regen braking.
+// Requires CAN to be initialized.
+
+#include <stdbool.h>
+
+#include "can.h"
+#include "can_msg_defs.h"
+#include "can_unpack.h"
+#include "status.h"
+
+StatusCode regen_braking_init(void);
+
+bool get_regen_braking_state(void);

projects/mci/src/main.c

@@ -17,6 +17,7 @@
 #include "motor_can.h"
 #include "motor_controller.h"
 #include "precharge_control.h"
+#include "regen_braking.h"
 
 #include "log.h"
 
@@ -83,6 +84,7 @@ int main(void) {
   prv_fan_control_init();
 
   drive_fsm_init();
+  regen_braking_init();
   Event e = { 0 };
   while (true) {
     while (event_process(&e) != STATUS_CODE_OK) {

projects/mci/src/mci_broadcast.c

@@ -93,6 +93,7 @@ static void prv_handle_speed_rx(const GenericCanMsg *msg, void *context) {
       critical_section_end(disabled);
       if (motor_id == LEFT_MOTOR_CONTROLLER) {
         cruise_rx_update_velocity(can_data.velocity_measurement.vehicle_velocity_ms);
+        mci_output_update_velocity(can_data.velocity_measurement.vehicle_velocity_ms);
       }
       break;
     }

projects/mci/src/mci_output.c

@@ -1,11 +1,13 @@
 #include "mci_output.h"
 
+#include <math.h>
 #include <string.h>
 
 #include "cruise_rx.h"
 #include "drive_fsm.h"
 #include "mci_events.h"
 #include "motor_can.h"
+#include "regen_braking.h"
 #include "wavesculptor.h"
 
 #include "exported_enums.h"
@@ -23,6 +25,12 @@ static float s_velocity_lookup[] = {
 
 static float s_max_regen_in_throttle = 0.0f;
 static float s_regen_threshold = 0.0f;
+static float s_actual_velocity_ms = 0.0f;
+
+// Updates s_actual_velocity_ms
+void mci_output_update_velocity(float actual_velocity_ms) {
+  s_actual_velocity_ms = actual_velocity_ms;
+}
 
 // Basic implementation of throttle/brake maps
 static float prv_brake_to_regen_map(float brake_value) {
@@ -59,6 +67,8 @@ static void prv_handle_drive(SoftTimerId timer_id, void *context) {
   MotorCanDriveCommand drive_command = { 0 };
   EEDriveOutput drive_state = drive_fsm_get_drive_state();
   bool is_cruise = drive_fsm_is_cruise();
+  bool is_regen_brake = get_regen_braking_state();
+
   // TODO(SOFT-122): Make sure test ensures that maps are continues
   if (drive_state == EE_DRIVE_OUTPUT_OFF) {
     drive_command.motor_current = 0.0f;
@@ -78,6 +88,13 @@ static void prv_handle_drive(SoftTimerId timer_id, void *context) {
     drive_command.motor_velocity =
         is_cruise ? cruise_rx_get_target_velocity() : s_velocity_lookup[drive_state];
   }
+
+  // Set current to zero if regen braking is disabled
+  // target velocity is less than actual velocity
+  if (!is_regen_brake && fabs(drive_command.motor_velocity) < fabs(s_actual_velocity_ms)) {
+    drive_command.motor_current = 0.0f;
+  }
+
   // Handling message
   prv_send_wavesculptor_message(storage, MOTOR_CAN_LEFT_DRIVE_COMMAND_FRAME_ID, drive_command);
   prv_send_wavesculptor_message(storage, MOTOR_CAN_RIGHT_DRIVE_COMMAND_FRAME_ID, drive_command);

projects/mci/src/regen_braking.c

@@ -0,0 +1,26 @@
+#include "regen_braking.h"
+
+#include "can.h"
+#include "can_msg_defs.h"
+#include "can_unpack.h"
+#include "status.h"
+
+static bool s_regen_braking_state;
+
+// Callback function to set the regen braking state
+static StatusCode prv_regen_braking_callback(const CanMessage *msg, void *context,
+                                             CanAckStatus *ack_reply) {
+  CAN_UNPACK_REGEN_BRAKING(msg, (uint8_t *)&s_regen_braking_state);
+  return STATUS_CODE_OK;
+}
+
+StatusCode regen_braking_init(void) {
+  // Default to enabled
+  s_regen_braking_state = true;
+  can_register_rx_handler(SYSTEM_CAN_MESSAGE_REGEN_BRAKING, prv_regen_braking_callback, NULL);
+  return STATUS_CODE_OK;
+}
+
+bool get_regen_braking_state(void) {
+  return s_regen_braking_state;
+}