Embedded

Getting Started

This page: structure of this subsystem

components/driving_board folder contains 4 libraries:

Firmware contains the generated CubeMX code. Don't edit this after generating, it will be rewritten after you generate again.

NOTE: do make sure that after generating your code in CubeMX, you run the post generation script. You can set a post generation script in CubeMX itself. However, if you use Windows run: scripts/post_code_generation.bash, if you use Mac run: scripts/post_code_generation_mac.bash

The Simulink folder contains code generated by the control team, and it shouldn't be modified by embedded. This code is not used on the embedded side, but it provides a clear reference for the type of input we give to control algorithm and the output we receive from it.

In control.h, struct ExtY gives the external outputs and ExtU is the struct for external inputs.


src/driving_board contains main.c

This is the code that runs when we build and update to the board by pio. Main includes multiple threads for some tasks that need to run concurrently.


ERC-Protobufs/components/driving_board contains protobuffers for this subsystem

Protobuffers are used to send information to software and debugging board and receiving information from software.

Motor Folder

components/driving_board/motor


All of the motor functions in this folder are called in Main

BLDC Motors:

They are used to control the speed of the rover.

bldc.c contains:

The set_bldc_pwm() method. This methods scales the control signal value calculated from control code and adjust the pwm duty cycle outputted by the STM32 accordingly.


Stepper Motors:

stepper.c contains:

The set_stepper_pwm() method. This methods scales the control signal value calculated from control code and adjust the pwm frequency outputted by the STM32 accordingly.


Encoders:

read_encoder.c contains:

The read encoders() method. This method reads encoder values of encoder angle, voltage generated and rpm.


Parser Folder

components/driving_board/parser


This page: structure of message encoding in parser.c

The encoding logic includes:


copy_motor_to_pb():

Copies each motor from internal MotorDiagnostic struct into protobuf MotorInformation.


DBMDiagnosticsEncode():

Encodes full diagnostics data into a protobuf message.

This function: Initializes the protobuf message Copies board state Copies all 10 motors into the protobuf structure Calls pb_message_encode to serialize data

The diagnostics message contains 10 motors:

front_left, middle_left, back_left, front_right, middle_right, back_right, steering_front_left, steering_back_left, steering_front_right, steering_back_right,

Each motor is copied using a loop into the protobuf message.


message_add_envelope():

This method wraps a protobuf message into a PBEnvelope using the same pb_message_encode function.

It: Takes a populated protobuf message (e.g. DrivingBoardDiagnostics) Initializes a PBEnvelope Sets the correct oneof field (e.g. drive_diag) Calls pb_message_encode on the envelope struct Returns encoded envelope buffer and length

Main

src/driving_board/main.c

contains the main firmware entry point and runtime logic for the driving board. The system is built on FreeRTOS (CMSIS-RTOS v2) and runs multiple tasks concurrently.


Initialization

init_board()

This function initializes the full system before starting the scheduler.

It:


Tasks

The system runs 3 main threads:

MainTask

This task handles: Ethernet communication Diagnostics message creation and sending Periodic data updates

Example Flow For Sending A Message:


PwmTask

This task runs the control loop.

It:


DrivingEncoderTask

This task processes encoder data.

It: