wiring_m328p.md

Heltec E-ink Modules

Wiring: Arduino Uno R3, Nano and other ATmega328P

❌ Connecting directly to display will cause damage.

These Arduinos operate at 5V. The display operates at 3.3V.
To connect safely, a "level-shifter" is needed.

Display	Arduino
VCC	3.3V
GND	GND
D/C	D2 *
SDI	D11
CS	D4 *
CLK	D13
BUSY	D5 *

* Can be changed. Set in constructor.

Suggested wiring, with level-shifting:

Note: The BUSY pin does not require level-shifting, as the Arduino only reads this pin, never outputting 5V.

(Optional) Suggested additional wiring, for power saving

void setup() {
    // Pin 7, PNP transistor
    display.useCustomPowerSwitch(7, PNP);

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

(Optional) Additional wiring: MicroSD card module

⚠ Connecting directly to MicroSD module may cause damage.

These Arduinos use 5V. MicroSD operates at 3.3V.
Your MicroSD module may have an inbuilt level shifter. Many do not.

This diagram shows possible wiring for MicroSD modules which do not have an inbuilt level-shifter. You may be able to connect directly.

❗ Take care when combining this wiring and useCustomPowerSwitch() The NPN or ACTIVE_LOW configurations will damage the SD card.

For greater protection, consider a bidirectional level shifter.