Unit Step16 Arduino Tutorial

/*
 * SPDX-FileCopyrightText: 2025 M5Stack Technology CO LTD
 *
 * SPDX-License-Identifier: MIT
 */
/*
 * @Hardwares: M5Stack PortA device + Unit Step16
 * @Dependent Library:
 * M5Unit-Step16:https://github.com/m5stack/M5Unit-Step16
 * @description: When the knob is rotated, only 0-8 is displayed,
 *              when raw value reaches 9-F, rotation direction is automatically reversed,
 *              LED brightness follows display value, never zero (minimum 10%),
 *              RGB color follows the 0-8 pattern
 */
#include <M5Unified.h>
#include <M5UnitStep16.h>

#define I2C_SDA_PIN     (2)
#define I2C_SCL_PIN     (1)
#define NUM_DIGITS      (9)
#define MAX_DIGIT       (8)
#define MIN_DIGIT       (0)
#define MIN_BRIGHTNESS  (10)
#define MAX_BRIGHTNESS  (100)
#define BRIGHTNESS_STEP (10)
#define RGB_BRIGHTNESS  (70)
#define LED_ALWAYS_ON   (0xFF)

UnitStep16 step16;
uint8_t currentDigit = 0;
uint8_t lastRawValue = 0;
bool isFirstRead     = true;

const uint8_t digitBrightness[NUM_DIGITS] = {
    MIN_BRIGHTNESS,                        // 0 - 10%
    MIN_BRIGHTNESS + BRIGHTNESS_STEP,      // 1 - 20%
    MIN_BRIGHTNESS + BRIGHTNESS_STEP * 2,  // 2 - 30%
    MIN_BRIGHTNESS + BRIGHTNESS_STEP * 3,  // 3 - 40%
    MIN_BRIGHTNESS + BRIGHTNESS_STEP * 4,  // 4 - 50%
    MIN_BRIGHTNESS + BRIGHTNESS_STEP * 5,  // 5 - 60%
    MIN_BRIGHTNESS + BRIGHTNESS_STEP * 6,  // 6 - 70%
    MIN_BRIGHTNESS + BRIGHTNESS_STEP * 7,  // 7 - 80%
    MIN_BRIGHTNESS + BRIGHTNESS_STEP * 8   // 8 - 90%
};

struct MyRGBColor {
    uint8_t r, g, b;
    const char* name;
};

const MyRGBColor digitColors[NUM_DIGITS] = {
    {0, 0, 128, "Deep Blue"},       // 0 - cold color
    {0, 64, 192, "Blue"},           // 1
    {0, 128, 255, "Light Blue"},    // 2
    {0, 192, 192, "Cyan"},          // 3
    {0, 255, 128, "Cyan Green"},    // 4
    {128, 255, 0, "Yellow Green"},  // 5
    {192, 192, 0, "Yellow"},        // 6
    {255, 128, 0, "Orange"},        // 7
    {255, 64, 0, "Orange Red"}      // 8 - warm color
};

uint8_t mapRawValueToDigit(uint8_t rawValue);
void updateDisplay(uint8_t digit);
uint8_t mapRawValueToDigit(uint8_t rawValue);
void updateDisplay(uint8_t digit);
void handleValueChange(uint8_t oldVal, uint8_t newVal);

void setup()
{
    M5.begin();
    Serial.begin(115200);
    Wire.begin(I2C_SDA_PIN, I2C_SCL_PIN);
    while(!step16.begin()){
        delay(1000);
        Serial.println("M5Unit-Step16 not found!");
    }
    M5.Display.fillRect(0, 0, 320, 240, WHITE);
    M5.Display.setTextColor(BLACK);
    M5.Display.setFont(&fonts::FreeMonoBold18pt7b);
    M5.Display.setCursor(0, 0);
    M5.Display.printf("M5Unit-Step16\n");
    step16.setRgbConfig(1);
    step16.setRgbBrightness(RGB_BRIGHTNESS);
    lastRawValue = step16.getValue();
    currentDigit = mapRawValueToDigit(lastRawValue);
    updateDisplay(currentDigit);
}

void loop()
{
    uint8_t rawValue = step16.getValue();
    if (rawValue != lastRawValue && !isFirstRead) {
        handleValueChange(lastRawValue, rawValue);
        lastRawValue = rawValue;
        M5.Display.fillRect(0, 0, 320, 240, WHITE);
        M5.Display.setCursor(0, 0);
        M5.Display.printf("Raw Value: %d\n", rawValue);
    }
    if (isFirstRead)    isFirstRead = false;
    delay(50);
}

/**
 * @brief Handle value change
 * @param oldVal Old raw value
 * @param newVal New raw value
 */
void handleValueChange(uint8_t oldVal, uint8_t newVal)
{
    if (newVal >= 9 && newVal <= 15) {
        uint8_t currentDirection = step16.getSwitchState();
        step16.setSwitchState(currentDirection == 0 ? 1 : 0);
    }
    uint8_t newDigit = mapRawValueToDigit(newVal);
    if (newDigit != currentDigit) {
        currentDigit = newDigit;
        updateDisplay(currentDigit);
    }
}

/**
 * @brief Map raw value to digit 0-8
 * @param rawValue Raw value (0-15)
 * @return Mapped digit (0-8)
 */
uint8_t mapRawValueToDigit(uint8_t rawValue)
{
    if (rawValue <= 8) {
        return rawValue;
    } else {
        return 17 - rawValue;
    }
}

/**
 * @brief Update display
 * @param digit Digit to display (0-8)
 */
void updateDisplay(uint8_t digit)
{
    if (digit > MAX_DIGIT) return;
    step16.setLedBrightness(digitBrightness[digit]);
    step16.setRgb(digitColors[digit].r, digitColors[digit].g, digitColors[digit].b);
    step16.setLedConfig(LED_ALWAYS_ON);
}