1. Two-cell mapping: VC7–VC6 and VC1–VC0, with VC6 through VC1 shorted.
2. Cell UV target: 3.20 V/cell, with autonomous DSG control.
3. Cell OV and temperature limits suitable for the selected 18650 chemistry.
4. RS1 = 1 mΩ.
5. OCD1 = −16 mV, nominally 16 A. OCD1 supports 2 mV steps.
6. SCD = −40 mV, nominally 40 A.
7. TS thermistor mode for the installed 10 kΩ NTC. BQ76907 supplies its own internal 20 kΩ thermistor bias.
8. Autonomous OV/UV/OCD/SCD FET-control masks, wake/sleep behavior, fault recovery, and ALERT behavior.
9. Host balancing policy with cell/temperature limits and periodic renewal.

Ini
[env:esp32-s3-mini-1-n8]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino
board_upload.flash_size = 8MB
board_build.flash_size = 8MB
board_build.partitions = default_8MB.csv
build_flags =
    -D ARDUINO_USB_MODE=1
    -D ARDUINO_USB_CDC_ON_BOOT=1
monitor_speed = 115200

Cpp
#include <Arduino.h>
#include <Wire.h>

static constexpr uint8_t PIN_MOTOR_ENABLE  = 4;
static constexpr uint8_t PIN_MOTOR_IN1     = 5;
static constexpr uint8_t PIN_MOTOR_IN2     = 6;
static constexpr uint8_t PIN_MOTOR_FAULT_N = 7;
static constexpr uint8_t PIN_BMS_SCL       = 9;
static constexpr uint8_t PIN_BMS_SDA       = 10;
static constexpr uint8_t PIN_BMS_ALERT_N   = 11;

static constexpr uint32_t HARD_MAX_PULSE_MS = 500;
static constexpr float MOTOR_INHIBIT_VOLTAGE_V = 6.6f;

struct BmsState {
  bool driverImplemented = false;
  bool communicationValid = false;
  bool configurationVerified = false;
  bool protectionFault = true;
  float packVoltageV = NAN;
  float cell1VoltageV = NAN;
  float cell2VoltageV = NAN;
  float temperatureC = NAN;
};

BmsState bms;

void bridgeOff() {
  digitalWrite(PIN_MOTOR_IN1, LOW);
  digitalWrite(PIN_MOTOR_IN2, LOW);
  digitalWrite(PIN_MOTOR_ENABLE, LOW);
}

bool hardwareFaultActive() {
  return digitalRead(PIN_MOTOR_FAULT_N) == LOW ||
         digitalRead(PIN_BMS_ALERT_N) == LOW;
}

bool initializeBq76907() {
  // Intentionally fail closed until the BQ76907 Technical Reference Manual
  // commands, data-memory addresses, CRC policy, thresholds and readback tests
  // are implemented. Never guess these values.
  bms.driverImplemented = false;
  bms.communicationValid = false;
  bms.configurationVerified = false;
  bms.protectionFault = true;
  return false;
}

bool refreshBq76907() {
  if (!bms.driverImplemented) return false;
  // TODO: read cell voltages, stack voltage, TS temperature, safety status,
  // FET status, ALERT causes and configuration checksum/readback.
  return false;
}

bool actuatorInterlockOk() {
  return bms.driverImplemented && bms.communicationValid &&
         bms.configurationVerified && !bms.protectionFault &&
         isfinite(bms.packVoltageV) &&
         bms.packVoltageV >= MOTOR_INHIBIT_VOLTAGE_V &&
         !hardwareFaultActive();
}

bool pulseMotor(bool forward, uint32_t durationMs) {
  if (!actuatorInterlockOk()) return false;
  durationMs = constrain(durationMs, 1UL, HARD_MAX_PULSE_MS);

  digitalWrite(PIN_MOTOR_IN1, LOW);
  digitalWrite(PIN_MOTOR_IN2, LOW);
  digitalWrite(PIN_MOTOR_ENABLE, HIGH);
  delay(5); // bounded direction dead-time

  digitalWrite(PIN_MOTOR_IN1, forward ? HIGH : LOW);
  digitalWrite(PIN_MOTOR_IN2, forward ? LOW : HIGH);

  const uint32_t started = millis();
  while (millis() - started < durationMs) {
    if (hardwareFaultActive() || !refreshBq76907()) {
      bridgeOff();
      return false;
    }
    delay(1);
  }

  bridgeOff();
  return true;
}

void setup() {
  pinMode(PIN_MOTOR_ENABLE, OUTPUT);
  pinMode(PIN_MOTOR_IN1, OUTPUT);
  pinMode(PIN_MOTOR_IN2, OUTPUT);
  bridgeOff();

  pinMode(PIN_MOTOR_FAULT_N, INPUT_PULLUP);
  pinMode(PIN_BMS_ALERT_N, INPUT_PULLUP);

  Serial.begin(115200);
  Wire.begin(PIN_BMS_SDA, PIN_BMS_SCL, 100000);
  Wire.setTimeOut(50);

  if (!initializeBq76907()) {
    Serial.println("BQ76907 driver/configuration not implemented: actuator locked out.");
  }
}

void loop() {
  refreshBq76907();
  if (hardwareFaultActive()) bridgeOff();
  delay(10);
}

• positively identifies U2 and validates I²C/CRC behavior;
• writes or loads the intended 2S protection configuration;
• reads every safety-critical setting back and compares it with the expected value;
• confirms both cells, temperature, FET state and safety status are valid;
• treats ALERT, communication loss, stale data, undervoltage, overtemperature and DRV8701 nFAULT as immediate motor-off conditions;
• uses a hard independent pulse timeout of 500 ms or less;
• refuses direction reversal until the bridge has returned to neutral;
• logs the exact configuration version/checksum used on each production board.