wiring_esp8266.md

Heltec E-ink Modules

Wiring: ESP8266

✅ ESP8266 uses 3.3V logic. It can connect directly to the display.

Note: labels are for the "GPIO" pins, not the "D1, D2, etc." labels printed on the board.

Display	ESP8266
VCC	3.3V
GND	GND
D/C	GPIO 2 *
SDI	GPIO 13
CS	GPIO 4 *
CLK	GPIO 14
BUSY	GPIO 5 *

* Can be set in constructor. Take care to avoid "iffy" pins on the ESP8266.

(Optional) Suggested additional wiring, for power saving

void setup() {
    // GPIO 0, PNP transistor
    display.useCustomPowerSwitch(0, PNP);

    //Later, when required:
    display.customPowerOff();
    display.customPowerOn();
}

(Optional) Additional wiring: MicroSD card module

✅ ESP8266 uses 3.3V logic. It can connect directly to microSD module.

void setup() {
    // Set MicroSD CS pin
    display.useSD(15);
}

Micro SD Module	ESP8266
VCC	3.3V
CS	GPIO 15
MOSI	GPIO 13
SCK	GPIO 14
MISO	GPIO 12
GND	GND

Some pins are shared with the display.

CS pin (card) must be set with useSD(cs)