Proximity Pilot Auto Ampacity

[chris1howell]

I would like to enable PP_AUTO in all builds. However with no cable/resistor attached it is stuck in State A.

PP_AUTO_AMPACITY — Allow Charging With No Cable Connected

Problem
When PP_AUTO_AMPACITY is enabled and no cable is connected (PP pin open/floating), the ADC reads ~1023. The lookup table finds no match and ReadPPMaxAmps() returns 0. AutoSetCurrentCapacity() treats 0 as invalid and returns 1 (error), causing StateTransitionReqFunc to force the state back to EVSE_STATE_A, blocking charging even when a vehicle is present on the pilot.

The root issue is that 0 is overloaded — it means both "short circuit on PP pin" (ADC ≤ 47, genuinely invalid) and "open circuit, no cable" (ADC > 819, no PP resistor present).

Fix — Distinguish Open Circuit from Short Circuit
AutoCurrentCapacityController.h

Add #define PP_AMPS_ABSENT 0xFF as a sentinel value for open-circuit PP pin.
AutoCurrentCapacityController.cpp — ReadPPMaxAmps()

Initialise amps = PP_AMPS_ABSENT instead of 0. The lookup loop sets a real value on a matched break. If the loop falls through without a match (ADC > 819, open circuit), amps remains PP_AMPS_ABSENT. The short-circuit case (ADC ≤ 47) still returns 0 because it matches the {0, 0} table entry on break.
AutoCurrentCapacityController.cpp — AutoSetCurrentCapacity()

Add a three-way branch:
PP_AMPS_ABSENT (0xFF) → no cable/PP resistor present, charge at configured capacity, return 0 (success)
amps > 0 → valid PP resistor found, cap current and return 0 (success)
amps == 0 → short on PP pin, block charging, return 1 (error)

AutoCurrentCapacityController.h — after the PP_AMPS typedef:

#define PP_AMPS_ABSENT 0xFF

AutoCurrentCapacityController.cpp — ReadPPMaxAmps(), change the initialiser:

  // default to absent; loop break sets a real value, fall-through means open circuit
  uint8_t amps = PP_AMPS_ABSENT;

AutoCurrentCapacityController.cpp — replace AutoSetCurrentCapacity() body:

uint8_t AutoCurrentCapacityController::AutoSetCurrentCapacity()
{
  uint8_t amps = ReadPPMaxAmps();

  if (amps == PP_AMPS_ABSENT) {
    // open circuit - no cable present, charge at configured capacity
    return 0;
  }
  else if (amps) {
    if (g_EvseController.GetCurrentCapacity() > ppMaxAmps) {
      g_EvseController.SetCurrentCapacity(ppMaxAmps,1,1);
    }
    return 0;
  }
  else {
    // ADC near zero - short on PP pin, block charging
    return 1;
  }
}