Marslib Power

This creates realistic brownout behavior in simulation — running all mechanisms simultaneously will drop voltage and trigger load shedding.

2. Key Rules

Rule A: Always Configure Both Current Limits

Every TalonFX MUST have both limits set in TalonFXConfiguration:

• Supply Current (e.g., 40A) — Limits raw battery draw. Prevents RoboRIO brownouts.
• Stator Current (e.g., 60A) — Limits magnetic torque. Prevents mechanism damage or carpet tearing.

If you skip either, a stalled motor will draw 200A+ and brownout the robot.

Rule B: CAN Bus Must Stay Below 80% Utilization

Reduce non-critical signal frequencies immediately on motor configuration:

BaseStatusSignal.setUpdateFrequencyForAll(4, // 4Hz for non-critical
    motor.getMotorVoltage(),
    motor.getDeviceTemp());

Only position, velocity, and stator current should run at full frequency (250Hz). Everything else should be 4-10Hz.

Rule C: Every Mechanism Must Implement Load Shedding

Every subsystem accepting a MARSPowerManager MUST dynamically scale its current limit based on system voltage:

double currentLimit = MathUtil.interpolate(
    MIN_CURRENT_AMPS, MAX_CURRENT_AMPS,
    (powerManager.getVoltage() - CRITICAL_VOLTAGE) / (NOMINAL_VOLTAGE - CRITICAL_VOLTAGE));
io.setCurrentLimit(Math.max(currentLimit, MIN_CURRENT_AMPS));

This is non-negotiable — it's the difference between a working robot and a brownout during eliminations.

Rule D: Power Constants Per Mechanism

Each mechanism defines its own voltage thresholds in Constants:

• NOMINAL_VOLTAGE — Voltage at which full current is allowed (typically 11.0V)
• CRITICAL_VOLTAGE — Voltage at which current is reduced to minimum (typically 7.0V)
• MAX_CURRENT_AMPS — Full-power current limit
• MIN_CURRENT_AMPS — Minimum current to maintain basic function

3. Adding Power Management to New Mechanisms

1. Accept MARSPowerManager in the subsystem constructor.
2. Define NOMINAL_VOLTAGE, CRITICAL_VOLTAGE, MAX_CURRENT_AMPS, MIN_CURRENT_AMPS in Constants.
3. In periodic(), compute the interpolated current limit and call io.setCurrentLimit().
4. In the IO layer's sim implementation, report current draw via MARSPhysicsWorld.getInstance().addFrameCurrentDrawAmps().

4. Telemetry

• Power/BatteryVoltage — Current battery voltage
• Power/IsBrownedOut — Boolean: voltage below critical threshold
• Power/TotalCurrentDraw — Aggregate current from all mechanisms (sim only)
• {Mechanism}/CurrentLimit — Active current limit after load shedding
• {Mechanism}/StatorCurrent — Actual stator current draw