Unit Scales Arduino Tutorial

#include <M5GFX.h>
#include <M5Unified.h>
#include <M5_Scales.h>

M5Canvas canvas(&M5.Display);
M5_Scales scales;

// LED color presets selected by the COLOR button.
constexpr uint8_t COLOR_COUNT = 3;
const uint32_t colorList[COLOR_COUNT] = {0xFF0000, 0x00FF00, 0x0000FF};
const char *const colorNames[COLOR_COUNT] = {"RED", "GREEN", "BLUE"};
const uint16_t colorBorders[COLOR_COUNT] = {TFT_RED, TFT_GREEN, TFT_BLUE};

// Bottom touch-button layout and screen refresh rate.
constexpr int16_t BUTTON_MARGIN = 4;
constexpr int16_t BUTTON_GAP = 4;
constexpr int16_t BUTTON_HEIGHT = 46;
constexpr uint32_t SCREEN_UPDATE_INTERVAL_MS = 100;

int16_t buttonWidth = 0;
int16_t buttonY = 0;
bool ledSync = false;
uint8_t colorIndex = 2;
uint32_t lastScreenUpdate = 0;
bool forceScreenUpdate = true;

// Calculate the left edge of a touch button.
int16_t getButtonX(uint8_t index) {
  return BUTTON_MARGIN + index * (buttonWidth + BUTTON_GAP);
}

// Return the touched button index, or -1 when outside all buttons.
int8_t getTouchedButton(int16_t x, int16_t y) {
  if (y < buttonY || y >= buttonY + BUTTON_HEIGHT)
    return -1;

  for (uint8_t i = 0; i < 3; ++i) {
    const int16_t buttonX = getButtonX(i);
    if (x >= buttonX && x < buttonX + buttonWidth)
      return i;
  }
  return -1;
}

// Draw one two-line touch button.
void drawButton(uint8_t index, const char *title, const char *value,
                uint16_t fillColor, uint16_t borderColor) {
  const int16_t x = getButtonX(index);

  canvas.fillRoundRect(x, buttonY, buttonWidth, BUTTON_HEIGHT, 4, fillColor);
  canvas.drawRoundRect(x, buttonY, buttonWidth, BUTTON_HEIGHT, 4, borderColor);
  canvas.drawRoundRect(x + 1, buttonY + 1, buttonWidth - 2, BUTTON_HEIGHT - 2,
                       3, borderColor);

  canvas.setFont(&fonts::Font2);
  canvas.setTextSize(1);
  canvas.setTextDatum(textdatum_t::middle_center);
  canvas.setTextColor(TFT_WHITE);
  canvas.drawString(title, x + buttonWidth / 2, buttonY + 13);
  canvas.drawString(value, x + buttonWidth / 2, buttonY + 33);
}

void drawScreen() {
  canvas.fillSprite(TFT_BLACK);
  canvas.setFont(&fonts::FreeMonoBold9pt7b);
  canvas.setTextSize(1);
  canvas.setTextDatum(textdatum_t::top_left);
  canvas.setTextColor(TFT_WHITE);

  // Read the latest Unit Scales status before drawing the frame.
  const int weight = scales.getWeight();
  const uint32_t adc = scales.getRawADC();
  const bool unitButtonPressed = scales.getBtnStatus();
  const uint8_t buttonCount = scales.getBtnPressedCount();
  const uint8_t longPressCount = scales.getBtnLongPressedCount();
  const uint32_t ledColor = scales.getLEDColor();

  canvas.drawCenterString("Unit Scales Status", 160, 5);
  canvas.drawString("WEIGHT: " + String(weight) + " g", 8, 28);
  canvas.drawString("RAW ADC: " + String(adc), 8, 50);
  canvas.drawString("UNIT BUTTON: " +
                        String(unitButtonPressed ? "PRESSED" : "RELEASED"),
                    8, 72);
  canvas.drawString("BUTTON COUNT: " + String(buttonCount), 8, 94);
  canvas.drawString("LONG PRESS: " + String(longPressCount), 8, 116);
  canvas.drawString("LED COLOR: 0x" + String(ledColor, HEX), 8, 138);
  canvas.drawString("LED SYNC: " + String(ledSync ? "ON" : "OFF"), 8, 160);

  drawButton(0, "LED SYNC", ledSync ? "ON" : "OFF",
             ledSync ? TFT_DARKGREEN : TFT_DARKGREY,
             ledSync ? TFT_GREEN : TFT_LIGHTGREY);
  drawButton(1, "SET", "OFFSET", TFT_DARKCYAN, TFT_CYAN);
  drawButton(2, "COLOR", colorNames[colorIndex], TFT_DARKGREY,
             colorBorders[colorIndex]);

  canvas.pushSprite(0, 0);
}

void handleTouch() {
  const auto touch = M5.Touch.getDetail();
  // Trigger an action only after a complete tap is released.
  if (!touch.wasClicked())
    return;

  switch (getTouchedButton(touch.x, touch.y)) {
  case 0: {
    // Toggle weight-based LED synchronization.
    const bool newLedSync = !ledSync;
    if (scales.setLEDSyncWeight(newLedSync)) {
      ledSync = newLedSync;
      if (!ledSync) {
        scales.setLEDColor(colorList[colorIndex]);
      }
      Serial.printf("LED Sync: %s\n", ledSync ? "ON" : "OFF");
    } else {
      Serial.println("Failed to change LED Sync");
    }
    break;
  }

  case 1:
    // Use the current ADC value as the zero offset.
    if (scales.setOffset()) {
      Serial.println("Offset set to current ADC value");
    } else {
      Serial.println("Failed to set offset");
    }
    break;

  case 2: {
    // Cycle through the predefined LED colors.
    const uint8_t newColorIndex = (colorIndex + 1) % COLOR_COUNT;
    if (scales.setLEDColor(colorList[newColorIndex])) {
      colorIndex = newColorIndex;
      Serial.printf("LED color: %s\n", colorNames[colorIndex]);
    } else {
      Serial.println("Failed to change LED color");
    }
    break;
  }

  default:
    return;
  }

  // Refresh the screen immediately after a successful touch action.
  forceScreenUpdate = true;
}

// Show a blocking startup error on the display.
void showConnectionError(const char *message) {
  canvas.fillSprite(TFT_BLACK);
  canvas.setFont(&fonts::FreeMonoBold9pt7b);
  canvas.setTextDatum(textdatum_t::middle_center);
  canvas.setTextColor(TFT_RED);
  canvas.drawString(message, canvas.width() / 2, canvas.height() / 2);
  canvas.pushSprite(0, 0);
}

void setup() {
  // Initialize CoreS3 display, touch, power, and internal peripherals.
  auto config = M5.config();
  config.clear_display = true;
  M5.begin(config);

  Serial.begin(115200);
  M5.Display.setRotation(1);

  // Render the complete UI in a 16-bit sprite to reduce flicker.
  canvas.setColorDepth(16);
  canvas.createSprite(M5.Display.width(), M5.Display.height());

  buttonWidth = (M5.Display.width() - BUTTON_MARGIN * 2 - BUTTON_GAP * 2) / 3;
  buttonY = M5.Display.height() - BUTTON_MARGIN - BUTTON_HEIGHT;

  Wire.end();
  while (!scales.begin(&Wire, EX_SDA, EX_SCL, M5_SCALES_DEFAULT_ADDR)) {
    showConnectionError("UNIT SCALES CONNECT ERROR");
    Serial.println("Unit Scales connect error");
    delay(1000);
  }

  // Apply the initial LED and onboard-button settings.
  bool initialized = true;
  initialized &= scales.setLEDSyncWeight(ledSync);
  initialized &= scales.setBtnOffsetControl(false);
  initialized &= scales.setLEDColor(colorList[colorIndex]);

  Serial.println(initialized ? "Unit Scales initialized"
                             : "Unit Scales initialization error");
  drawScreen();
}

void loop() {
  // Refresh touch state before checking screen input.
  M5.update();
  handleTouch();

  // Limit display and Unit Scales polling to the configured interval.
  const uint32_t now = millis();
  if (forceScreenUpdate ||
      now - lastScreenUpdate >= SCREEN_UPDATE_INTERVAL_MS) {
    drawScreen();
    lastScreenUpdate = now;
    forceScreenUpdate = false;
  }

  delay(10);
}