Firmware

Teensy 4.1 firmware for the distributed CAN control system.

Source Files

Dependencies

; platformio.ini
[env:teensy41]
platform = teensy
board = teensy41
framework = arduino
lib_deps =
    FlexCAN_T4
    Adafruit MCP4728

Master Node

Receives serial commands from main computer, broadcasts CAN messages to actuators.

Serial Input (115200 baud):

T <0.0-1.0>     # Throttle
S <-1.0-1.0>    # Steering
B <0.0-1.0>     # Brake
M <N/D/S/R>     # Drive mode
E <0/1>         # E-Stop

Key Functions:

• sendThrottle(estop, value, mode) → ID 0x100

• sendSteer(center, value) → ID 0x200

• sendBrake(estop, value) → ID 0x300

Steering Node

Closed-loop stepper motor position control.

Calibration (line 18-20):

const int leftAnalogReading  = 350;  // ADC at full LEFT
const int rightAnalogReading = 820;  // ADC at full RIGHT
const int BAND               = 5;    // deadband

Control Loop: Reads analog feedback, steps motor toward setpoint.

Throttle Node

MCP4728 DAC control for throttle voltage and drive mode lines.

Calibration (line 34-36):

static constexpr float THROTTLE_IDLE_V = 0.30f;
static constexpr float THROTTLE_MAX_V  = 4.00f;

Watchdog: 200ms timeout → Neutral + Idle

Brake Node

H-bridge PWM control for linear actuator.

Calibration (line 29-30):

const int maxAnalogReading = 805;  // ADC at FULL EXTEND
const int minAnalogReading = 735;  // ADC at FULL RETRACT

Watchdog: 100ms timeout → Full brake (E-STOP behavior)

Flashing

# PlatformIO
pio run -t upload

# Arduino IDE
# Select Board: Teensy 4.1, then Upload

# Teensy Loader CLI
teensy_loader_cli --mcu=TEENSY41 -w firmware.hex