Firmware for the Karca Engine Control Box

Project status

This project is under active development. Currently, the firmware is being tested on the NUCLEO-F207 development board. We will eventually migrate to the STM32F407VET6

Overview

This repository contains the STM32Cube IDE project with the firmware running on the STM32F407 controller for Proxima's Engine Control Box. The code aims to fulfil the same objective as slonk and RESFET. These are as follows:

• Collect Data from the sensors and relay it to the operator over TCP at a minimum rate of 10Hz
• Receive Commands from the operator over TCP and actuate the corresponding valves/ignition relay
• Support a faster sampling rate (up to 5kHz) during ignition

Motivation

The engine control firmware was written (yet again!) as part of the team's move away from the Raspberry Pi-based system and towards a microcontroller. The reasons for the switch are as follows:

• Deterministic sampling and actuation. The STM32 uses a real-time operating system that reduces the timing uncertainty during data collection and valve actuation
• Wider range of peripherals. The STM32 has three SPI peripherals and three 12-bit internal ADCs, which provide more headroom for expansion in case more sensors are needed
• Low power consumption

However, if future members decide to move back to the Raspberry Pi, they are strongly recommended to reuse and adapt the slonk engine control software.

Installation

Install STM32CubeIDE and STM32CubeMX

Clone the repository git clone https://github.com/rice-eclipse/mc-firmware

Open STM32CubeIDE and set the root directory of the repository as the workspace

Build f407-firmware to build the code for the controller running on the engine control box

Run the code using the GUI

Hardware Stack

• MCU: STM32F407 (ARM Cortex-M4 CPU)
• Sensors: Thermocouples, Load Cells, Pressure Transducers
• Sensor Interface 12-bit, 8 channel MCP3208 ADC (SPI interface)
• Wireless Communication Websocket connection over LwIP (Lightweight IP TCP implementation)

Software Design

The system is divided into isolated tasks managed by the FreeRTOS scheduler:

1. Data Reading
   • Processes raw data from the ADCs and stores it in a shared buffer.
2. Command Handling
   • Processes incoming commands from the Ground Station.
3. Data Sending
   • Writes flight data to SD Card for onboard storage.
   • Transmits real-time data via WebSocket to the Ground Station Dashboard (Quonkboard) at a decimated interval.

Development Environment

• Language: C
• OS: FreeRTOS