The Hull Controller is an Arduino Nano-based subsystem that operates as an I2C slave at address 0x08. It provides low-level control over the RC tank’s hardware components — including tracks, turret motors, lights, weapons, and battery monitoring.

Communication with the controller is handled via a command-response protocol over I2C. The Raspberry Pi (Turret Controller) acts as the master.

Each command consists of two bytes:

Data values are often scaled where 100 = neutral / zero point. For example:

• 0–99 → Negative range (-100% to 0%)
• 101–200 → Positive range (0% to +100%)

Responses depend on the request command. Data is transmitted back to the I2C master when it issues a read request.

Each bit in the status byte corresponds to a specific system state flag:

Raw  Data  →  Mapped Speed (%)
0     →  -100
50    →  -50
100   →   0
150   →  +50
200   →  +100

Voltage (V) = (raw / 1023.0) * 5.0 * (R1 + R2) / R2
Example: R1=100kΩ, R2=22kΩ → Scale ≈ 5.545x

import smbus
bus = smbus.SMBus(1)
ADDR = 0x08

# Move forward 50%
bus.write_byte_data(ADDR, 0x20, 150)

# Turn on front lights
bus.write_byte_data(ADDR, 0x40, 1)

# Fire cannon
bus.write_byte_data(ADDR, 0x32, 128)

# Read battery voltage
bus.write_byte(ADDR, 0xE0)
data = bus.read_i2c_block_data(ADDR, 0, 5)
voltage = (data[0] | (data[1] << 8)) / 100.0
print(f"Battery: {voltage}V")

#include <Wire.h>
#define HULL_ADDR 0x08

void setup() {
  Wire.begin();
  Serial.begin(115200);
  delay(1000);
}

void loop() {
  sendCommand(0x20, 150); // Move forward
  delay(1000);
  sendCommand(0x21, 100); // Stop turning
}

void sendCommand(byte cmd, byte val) {
  Wire.beginTransmission(HULL_ADDR);
  Wire.write(cmd);
  Wire.write(val);
  byte error = Wire.endTransmission();
  if (error) Serial.printf("I2C error: %d\n", error);
}

Safety Notes:

• Always issue 0xFF,0 (E-stop) before performing maintenance.
• Ensure logic and motor grounds are common.
• Avoid sending commands faster than 20ms intervals.

Errors are cleared automatically when the fault condition is removed. The status byte’s ERROR bit resets when systemError = false.