Unit 4Relay Arduino Tutorial

#include <M5Unified.h>
#include "Unit_4RELAY.h"

UNIT_4RELAY relay;

namespace {
constexpr uint16_t COLOR_BG      = 0x1082;
constexpr uint16_t COLOR_SURFACE = 0x2104;
constexpr uint16_t COLOR_HEADER  = 0x0349;
constexpr uint16_t COLOR_BORDER  = 0x52AA;
constexpr uint16_t COLOR_MUTED   = 0xBDF7;
constexpr uint16_t COLOR_GREEN   = 0x2E8B;
constexpr uint16_t COLOR_RED     = 0xD249;
constexpr uint16_t COLOR_AMBER   = 0xFD20;

constexpr int16_t CHANNEL_Y      = 148;
constexpr int16_t CHANNEL_WIDTH  = 68;
constexpr int16_t CHANNEL_HEIGHT = 43;
constexpr int16_t CHANNEL_GAP    = 8;

uint8_t stepIndex = 0;
bool syncMode     = false;
bool allOn        = false;
bool relayState[4] = {false, false, false, false};
bool ledState[4]   = {false, false, false, false};

void drawModeStatus()
{
    M5.Display.fillRect(0, 38, 320, 36, COLOR_BG);
    M5.Display.setFont(&fonts::Font2);
    M5.Display.setTextDatum(textdatum_t::middle_left);
    M5.Display.setTextColor(COLOR_MUTED, COLOR_BG);
    M5.Display.drawString("MODE", 12, 56);
    M5.Display.drawString("CONTROL", 161, 56);

    const uint16_t modeColor = syncMode ? COLOR_GREEN : COLOR_AMBER;
    M5.Display.fillRoundRect(57, 44, 82, 25, 4, modeColor);
    M5.Display.fillRoundRect(231, 44, 77, 25, 4, COLOR_SURFACE);
    M5.Display.drawRoundRect(231, 44, 77, 25, 4, COLOR_BORDER);

    M5.Display.setTextDatum(textdatum_t::middle_center);
    M5.Display.setTextColor(TFT_BLACK, modeColor);
    M5.Display.drawString(syncMode ? "SYNC" : "ASYNC", 98, 56);
    M5.Display.setTextColor(TFT_WHITE, COLOR_SURFACE);
    M5.Display.drawString(syncMode ? "RELAY" : "LED", 269, 56);
}

void drawAction(const char *message)
{
    M5.Display.fillRoundRect(10, 81, 300, 38, 4, COLOR_SURFACE);
    M5.Display.drawRoundRect(10, 81, 300, 38, 4, COLOR_BORDER);
    M5.Display.setFont(&fonts::Font2);
    M5.Display.setTextDatum(textdatum_t::middle_left);
    M5.Display.setTextColor(COLOR_MUTED, COLOR_SURFACE);
    M5.Display.drawString("LAST ACTION", 20, 100);
    M5.Display.setTextColor(TFT_WHITE, COLOR_SURFACE);
    M5.Display.drawString(message, 119, 100);
}

void drawChannel(uint8_t channel)
{
    const bool isOn       = syncMode ? relayState[channel] : ledState[channel];
    const uint16_t color  = isOn ? COLOR_GREEN : COLOR_BORDER;
    const int16_t x       = 10 + channel * (CHANNEL_WIDTH + CHANNEL_GAP);
    char channelLabel[5]  = {};
    snprintf(channelLabel, sizeof(channelLabel), "CH%u",
             static_cast<unsigned>(channel + 1));

    M5.Display.fillRoundRect(x, CHANNEL_Y, CHANNEL_WIDTH, CHANNEL_HEIGHT, 4,
                             COLOR_SURFACE);
    M5.Display.drawRoundRect(x, CHANNEL_Y, CHANNEL_WIDTH, CHANNEL_HEIGHT, 4,
                             color);
    M5.Display.setTextDatum(textdatum_t::middle_center);
    M5.Display.setFont(&fonts::Font2);
    M5.Display.setTextColor(COLOR_MUTED, COLOR_SURFACE);
    M5.Display.drawString(channelLabel, x + CHANNEL_WIDTH / 2, CHANNEL_Y + 12);
    M5.Display.setTextColor(isOn ? COLOR_GREEN : TFT_WHITE, COLOR_SURFACE);
    M5.Display.drawString(isOn ? "ON" : "OFF", x + CHANNEL_WIDTH / 2,
                          CHANNEL_Y + 31);
}

void drawAllChannels()
{
    M5.Display.fillRect(0, 125, 320, 22, COLOR_BG);
    M5.Display.setFont(&fonts::Font2);
    M5.Display.setTextDatum(textdatum_t::middle_left);
    M5.Display.setTextColor(COLOR_MUTED, COLOR_BG);
    M5.Display.drawString(syncMode ? "RELAY STATUS" : "LED STATUS", 10, 136);

    for (uint8_t channel = 0; channel < 4; ++channel) {
        drawChannel(channel);
    }
}

void drawButtonHint(int16_t x, char button, const char *label, uint16_t color)
{
    char buttonLabel[2] = {button, '\0'};

    M5.Display.fillCircle(x, 220, 11, color);
    M5.Display.setFont(&fonts::Font2);
    M5.Display.setTextDatum(textdatum_t::middle_center);
    M5.Display.setTextColor(TFT_BLACK, color);
    M5.Display.drawString(buttonLabel, x, 220);
    M5.Display.setTextDatum(textdatum_t::middle_left);
    M5.Display.setTextColor(TFT_WHITE, COLOR_SURFACE);
    M5.Display.drawString(label, x + 16, 220);
}

void drawMainUi()
{
    M5.Display.fillScreen(COLOR_BG);
    M5.Display.fillRect(0, 0, 320, 34, COLOR_HEADER);
    M5.Display.setFont(&fonts::Font4);
    M5.Display.setTextDatum(textdatum_t::middle_center);
    M5.Display.setTextColor(TFT_WHITE, COLOR_HEADER);
    M5.Display.drawString("UNIT 4RELAY", 160, 17);

    drawModeStatus();
    drawAction("Ready");
    drawAllChannels();

    M5.Display.fillRect(0, 202, 320, 38, COLOR_SURFACE);
    M5.Display.drawFastHLine(0, 202, 320, COLOR_BORDER);
    drawButtonHint(15, 'A', "STEP", COLOR_GREEN);
    drawButtonHint(121, 'B', "MODE", COLOR_AMBER);
    drawButtonHint(229, 'C', "ALL", COLOR_RED);
}

void updateStateAfterAllWrite(bool state)
{
    // relayAll() and ledAll() overwrite the complete output register.
    for (uint8_t channel = 0; channel < 4; ++channel) {
        relayState[channel] = syncMode ? state : false;
        ledState[channel]   = syncMode ? false : state;
    }
}
}  // namespace

void setup()
{
    M5.begin();
    Serial.begin(115200);

    M5.Display.setRotation(1);
    relay.begin(&Wire, 21, 22);
    relay.Init(false);  // Start in asynchronous mode with all outputs off.
    drawMainUi();
}

void loop()
{
    M5.update();

    if (M5.BtnA.wasPressed()) {
        const uint8_t channel = stepIndex % 4;
        const bool state      = stepIndex < 4;
        char message[20]      = {};

        if (syncMode) {
            relay.relayWrite(channel, state);
            relayState[channel] = state;
        } else {
            relay.ledWrite(channel, state);
            ledState[channel] = state;
        }

        snprintf(message, sizeof(message), "%s %u  %s",
                 syncMode ? "Relay" : "LED",
                 static_cast<unsigned>(channel + 1),
                 state ? "ON" : "OFF");
        drawAction(message);
        drawChannel(channel);
        stepIndex = (stepIndex + 1) % 8;
    }

    if (M5.BtnB.wasPressed()) {
        syncMode = !syncMode;
        relay.switchMode(syncMode);
        drawModeStatus();
        drawAction(syncMode ? "Sync mode enabled" : "Async mode enabled");
        drawAllChannels();
    }

    if (M5.BtnC.wasPressed()) {
        allOn = !allOn;
        if (syncMode) {
            relay.relayAll(allOn);
        } else {
            relay.ledAll(allOn);
        }

        updateStateAfterAllWrite(allOn);
        drawAction(allOn ? "All channels ON" : "All channels OFF");
        drawAllChannels();
    }
}