• MCU/module: ESP32-S3-MINI-1-N8 direct-solder module
• Framework: Arduino / ESP32 board support 3.x
• Build system: PlatformIO
• Debug/command interface: native USB Serial/JTAG via board USB-C connector

• U10 VDD is 3.3V only from VCC_3V3; never connect VM_5V to the module.
• Manual reset: SW1 pulls EN low.
• Manual boot: SW2 pulls IO0 low for download mode if needed.
• Native USB: IO19 = USB_D_N, IO20 = USB_D_P.

Ini
[env:esp32-s3-mini-1]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600
board_build.flash_size = 8MB
board_build.arduino.memory_type = qio_opi
build_flags =
    -D ARDUINO_USB_MODE=1
    -D ARDUINO_USB_CDC_ON_BOOT=1

Cpp
#include <Arduino.h>

// Matrix geometry
constexpr uint8_t ROWS = 8;
constexpr uint8_t COLS = 6;

// Pulse timing defaults
uint16_t PULSE_MS = 15;
constexpr uint16_t SETTLE_MS = 3;
constexpr uint16_t MAX_PULSE_MS = 50;

// ROW rail control pins: each rail has IN1, IN2 to one DRV8833 half-bridge.
const uint8_t ROW_IN1[ROWS] = {1, 3, 5, 7, 9, 11, 13, 15};
const uint8_t ROW_IN2[ROWS] = {2, 4, 6, 8, 10, 12, 14, 16};

// COL rail control pins.
const uint8_t COL_IN1[COLS] = {17, 21, 34, 36, 38, 40};
const uint8_t COL_IN2[COLS] = {18, 33, 35, 37, 39, 41};

constexpr uint8_t STATUS_LED_PIN = 48;

// DRV8833 single-ended rail states using OUT1 only:
// IN1=0, IN2=0: high-Z / coast
// IN1=1, IN2=0: OUT1 high
// IN1=0, IN2=1: OUT1 low
// IN1=1, IN2=1: brake, avoided
void railHiZ(uint8_t in1, uint8_t in2) {
  digitalWrite(in1, LOW);
  digitalWrite(in2, LOW);
}

void railHigh(uint8_t in1, uint8_t in2) {
  digitalWrite(in1, HIGH);
  digitalWrite(in2, LOW);
}

void railLow(uint8_t in1, uint8_t in2) {
  digitalWrite(in1, LOW);
  digitalWrite(in2, HIGH);
}

void allRailsHiZ() {
  for (uint8_t r = 0; r < ROWS; r++) railHiZ(ROW_IN1[r], ROW_IN2[r]);
  for (uint8_t c = 0; c < COLS; c++) railHiZ(COL_IN1[c], COL_IN2[c]);
}

void initMatrixPins() {
  for (uint8_t r = 0; r < ROWS; r++) {
    pinMode(ROW_IN1[r], OUTPUT);
    pinMode(ROW_IN2[r], OUTPUT);
  }
  for (uint8_t c = 0; c < COLS; c++) {
    pinMode(COL_IN1[c], OUTPUT);
    pinMode(COL_IN2[c], OUTPUT);
  }
  allRailsHiZ();
}

void flipCell(uint8_t row, uint8_t col, bool whiteFaceUp) {
  if (row >= ROWS || col >= COLS) return;

  allRailsHiZ();
  delay(SETTLE_MS);

  if (whiteFaceUp) {
    // Forward current: ROW high, COL low.
    railHigh(ROW_IN1[row], ROW_IN2[row]);
    railLow(COL_IN1[col], COL_IN2[col]);
  } else {
    // Reverse current: ROW low, COL high.
    railLow(ROW_IN1[row], ROW_IN2[row]);
    railHigh(COL_IN1[col], COL_IN2[col]);
  }

  delay(PULSE_MS);
  allRailsHiZ();
  delay(SETTLE_MS);
}

void setAll(bool whiteFaceUp) {
  for (uint8_t r = 0; r < ROWS; r++) {
    for (uint8_t c = 0; c < COLS; c++) {
      flipCell(r, c, whiteFaceUp);
    }
  }
}

void checkerboard(bool invert) {
  for (uint8_t r = 0; r < ROWS; r++) {
    for (uint8_t c = 0; c < COLS; c++) {
      flipCell(r, c, ((r + c) & 1) ^ invert);
    }
  }
}

void sweep() {
  for (uint8_t r = 0; r < ROWS; r++) {
    for (uint8_t c = 0; c < COLS; c++) {
      flipCell(r, c, true);
    }
  }
  for (uint8_t r = 0; r < ROWS; r++) {
    for (uint8_t c = 0; c < COLS; c++) {
      flipCell(r, c, false);
    }
  }
}

void halfSelectTest() {
  // Pulses one selected cell repeatedly; surrounding same-row/same-col cells should not move.
  for (uint8_t i = 0; i < 10; i++) {
    flipCell(0, 0, true);
    delay(100);
    flipCell(0, 0, false);
    delay(100);
  }
}

void printHelp() {
  Serial.println("Commands:");
  Serial.println("  c              clear all cells");
  Serial.println("  s              set all cells");
  Serial.println("  k              checkerboard");
  Serial.println("  K              inverse checkerboard");
  Serial.println("  w              sweep");
  Serial.println("  h              half-select test at R0 C0");
  Serial.println("  f R C T        flip row R col C to target T (0/1)");
  Serial.println("  p N            set pulse width in ms, clamped to MAX_PULSE_MS");
}

void handleCommand(String line) {
  line.trim();
  if (line.length() == 0) return;

  if (line == "c") setAll(false);
  else if (line == "s") setAll(true);
  else if (line == "k") checkerboard(false);
  else if (line == "K") checkerboard(true);
  else if (line == "w") sweep();
  else if (line == "h") halfSelectTest();
  else if (line[0] == 'p') {
    int n = line.substring(1).toInt();
    if (n > 0) PULSE_MS = min<uint16_t>(n, MAX_PULSE_MS);
    Serial.printf("PULSE_MS=%u\n", PULSE_MS);
  } else if (line[0] == 'f') {
    int r = -1, c = -1, t = -1;
    if (sscanf(line.c_str(), "f %d %d %d", &r, &c, &t) == 3) {
      flipCell((uint8_t)r, (uint8_t)c, t != 0);
    } else {
      Serial.println("Usage: f R C T");
    }
  } else {
    printHelp();
  }
}

void setup() {
  pinMode(STATUS_LED_PIN, OUTPUT);
  digitalWrite(STATUS_LED_PIN, LOW);

  initMatrixPins();

  Serial.begin(115200);
  unsigned long start = millis();
  while (!Serial && (millis() - start < 1500)) {
    delay(10);
  }

  digitalWrite(STATUS_LED_PIN, HIGH);
  Serial.println("ESP32-S3-MINI-1 Flipdot 6x8 firmware ready.");
  printHelp();
}

void loop() {
  if (Serial.available()) {
    String line = Serial.readStringUntil('\n');
    handleCommand(line);
  }
}

Bash
pio run
pio run -t upload
pio device monitor -b 115200