CrowPanel ESP32-S3 4.2” E-paper HMI Display: high-resolution pinout, datasheet and specs

// Sketch: CrowPanel 4.2" E-Paper UI Demo
// Description: Simple demonstration of initializing and displaying a message on the CrowPanel ESP32-S3 4.2" e-paper display
// Author: Renzo Mischianti
// Website: mischianti.org

#include "GxEPD2_BW.h"        // Core library for driving black & white e-paper panels
#include <Arduino.h>          // Standard Arduino core (for pinMode, digitalWrite, etc.)

// =======================
// Button pin definitions
// =======================
// All buttons are wired active-LOW with internal pullups enabled.
// Pressing a button connects the pin to GND.
#define HOME_KEY   2   // “Home” button, returns UI to main screen
#define EXIT_KEY   1   // “Exit” button, powers down or quits app
#define PREV_KEY   6   // “Up/Previous” navigation button
#define NEXT_KEY   4   // “Down/Next” navigation button
#define OK_KEY     5   // “OK/Select” button

// =================================
// E-paper power & control pin defs
// =================================
#define PWR        7   // Power‐enable pin: HIGH = display powered on, LOW = off
#define BUSY       48  // BUSY pin from panel: HIGH = busy drawing, LOW = ready
#define RST        47  // RST (Reset) pin: pulse LOW to reset the panel
#define DC         46  // D/C (Data/Command) pin: LOW = command, HIGH = data
#define CS         45  // CS (Chip Select) pin for SPI transactions

// ================================
// SD card & (optional) TFT SPI pins
// ================================
#define TFT_SCK    12  // SPI clock for optional TFT (shared SPI bus)
#define TFT_MOSI   11  // SPI MOSI  for optional TFT (shared SPI bus)
#define SD_MOSI    40  // SPI MOSI  for microSD card
#define SD_MISO    13  // SPI MISO  for microSD card
#define SD_SCK     39  // SPI clock for microSD card
#define SD_CS      10  // Chip-select for microSD card

// ========================================
// General-purpose header: 12 GPIO pins map
// ========================================
// These are exposed on the 2×6 header for your own sensors or peripherals.
// Underneath, 4× GND pins and 4× 3V3 pins are wired in parallel for easy wiring.
int pin_Num[12] = {
  3,   8,   // Row 1: left=GPIO3, right=GPIO8
  9,  14,   // Row 2: left=GPIO9, right=GPIO14
  15, 16,   // Row 3: left=GPIO15, right=GPIO16
  17, 18,   // Row 4: left=GPIO17, right=GPIO18
  19, 20,   // Row 5: left=GPIO19, right=GPIO20
  21, 38    // Row 6: left=GPIO21, right=GPIO38
};

/*
+--------------+
|  3        8  |
|  9       14  |
| 15       16  |
| 17       18  |
| 19       20  |
| 21       38  |
| GND     3v3  |
| GND     3v3  |
| GND     3v3  |
| GND     3v3  |
+--------------+
 */

// ==============================
// Instantiate the e-paper object
// ==============================
// Template parameters:
//  - Driver type: GxEPD2_420_GYE042A87   (4.2", 400×300 px, SSD1683)
//  - Height macro: GxEPD2_420_GYE042A87::HEIGHT
//
// Constructor parameters order: CS, D/C, RST, BUSY
GxEPD2_BW<GxEPD2_420_GYE042A87, GxEPD2_420_GYE042A87::HEIGHT>
  epd(GxEPD2_420_GYE042A87(CS, DC, RST, BUSY));

// ====================================
// epdPower()
//   Controls the display power rail.
//   HIGH = on, LOW = off.
// ====================================
void epdPower(int state) {
  pinMode(PWR, OUTPUT);
  digitalWrite(PWR, state);
}

// ====================================
// epdInit()
//   Initializes SPI, resets the panel,
//   sets orientation, text color & size,
//   and configures full-window buffering.
// ====================================
void epdInit() {
  // SPI baudrate: 115200 bps, perform hardware reset, reset pulse=50ms, skipInit=false
  epd.init(115200, true, 50, false);

  // Set screen orientation: 0 = portrait, other values rotate 90°/180°/270°
  epd.setRotation(0);

  // All subsequent text will be drawn in black
  epd.setTextColor(GxEPD_BLACK);

  // Default text size multiplier (1=6×8px font, 2=12×16px, etc.)
  epd.setTextSize(2);

  // Allocate enough RAM for full-height buffering (300px),
  // speeding up screen updates at the cost of memory.
  epd.setFullWindow();
}

void setup() {
  // Turn on the e-paper panel's power rail
  epdPower(HIGH);

  // Initialize the display (SPI, reset, look&feel)
  epdInit();

  // Fill the memory buffer & screen with white
  epd.fillScreen(GxEPD_WHITE);

  // Draw a black border rectangle around the full 400×300 pixel area
  epd.drawRect(0, 0, 400, 300, GxEPD_BLACK);

  // Position the text cursor at X=40px, Y=130px from the top-left corner
  epd.setCursor(40, 130);

  // Print our welcome message
  epd.print("Hello from mischianti.org!");

  // Send the buffered content to the panel (single update)
  epd.display();

  // Put the panel into ultra-low-power sleep mode
  epd.hibernate();

  // Optionally cut the power rail to reduce consumption further
  epdPower(LOW);
}

void loop() {
  // Nothing to do here—everything happens once in setup()
}