PDU

PDU controls and monitors low-voltage power rails and cooling hardware for the car.

Responsibilities

• Control switchable rails (GPIO outputs).
• Sample ADC channels for rail voltage/current telemetry.
• Scan rail nFAULT lines and report/latch faults.
• Control fan/pump/hxfan outputs and fan PWM duty cycles.
• Publish PDU telemetry and coolant output status over CAN.

Module Layout

• main.c
  • Board init, peripheral init, task definitions, task startup order.
  • No business logic beyond orchestration.
• state.c / state.h
  • Shared runtime state (g_pdu_state) for all PDU logic.
• switches.c / switches.h
  • Switch command/read API.
  • ADC and mux measurement pipeline.
  • Rail current/voltage conversions.
  • Default-rail enable sequence.
• faults.c / faults.h
  • Table-driven nFAULT polling.
  • One-fault-slot-per-cycle update cadence.
  • Rail fault LED behavior.
• cooling.c / cooling.h
  • Cooling policy computation.
  • Cooling actuation (switches + fan PWM).
  • Cooling CAN output publication.
• cooling_bangbang.c / cooling_bangbang.h
  • Optional bang-bang policy backend.
  • Compiled in but disabled by default.
• telemetry.c / telemetry.h
  • Power/thermal telemetry CAN publication.
  • Flowrate telemetry CAN publication.
• Hardware adapter modules (kept separate):
  • led/
  • fan_control/
  • flow_rate/

Runtime State (g_pdu_state)

The shared state contains:

• rail_voltage_mv for 24V/5V/3V3 measurements.
• switch_current_ma[] for sensed currents (switch and rail channels).
• mux_adc_counts[] and next_mux_channel for mux-sampled inputs.
• next_rail_fault_index for staggered rail fault scanning.
• cooling_command for requested/applied cooling outputs.

Task Model

Defined in main.c:

• CAN_rx_update (0 ms)
• CAN_tx_update (5 ms)
• switches_periodic (15 ms)
• cooling_periodic (100 ms)
• faults_periodic (100 ms)
• fault_library_periodic (100 ms)
• telemetry_flow_periodic (200 ms)
• LED_periodic (500 ms)
• telemetry_power_periodic (500 ms)
• Heartbeat task (LED sweep callback)

Cooling Backend: Bang-Bang (Disabled by Default)

The bang-bang backend is present for future policy work, but disabled to preserve current behavior.

• Toggle: COOLING_ENABLE_BANGBANG in cooling_bangbang.h
  • 0 (default): backend is a no-op.
  • 1: motor temp based bang-bang updates are applied.

Current non-bangbang behavior remains the active policy path.