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Heltec E-Ink Modules - Wireless Paper

In addition to the line of SPI E-Ink displays, Heltec sell an all-in-one board, "Wireless Paper".

Features:

  • ESP32-S3 Microcontroller
  • 2.13" Black and White E-Ink display
  • WiFi, Bluetooth & LoRa connectivity

Only the board's E-Ink display falls within the scope of this library.

Getting Started

Arduino IDE

  1. Open preferences

  2. Open "Additional board manager URLs"

  3. Add the URL: https://github.com/Heltec-Aaron-Lee/WiFi_Kit_series/releases/latest/download/package_heltec_esp32_index.json

  4. Open the Board Manager, search for Heltec, and install the latest version of Heltec ESP32 Series Dev-boards.
    This may take some time.

  5. With your "Wireless Paper" connected, open the board selection drop-dowm, search for "paper", then select Wireless Paper, and your board's serial port.

PlatformIO

(Alternative to Arduino IDE)

Add the following entry to your platformio.ini file

[env:wireless_paper]
platform = espressif32
board = heltec_wifi_lora_32_V3
framework = arduino
monitor_speed = 115200
monitor_filters = esp32_exception_decoder
lib_deps = https://github.com/todd-herbert/heltec-eink-modules

Using the library

Check out the examples, such as File > Examples > heltec-eink-modules > WirelessPaper > basic
Make sure to select your display model first, at the top of the sketch.

The upload process will be slow when compiling for the first time. Saving your sketch allows the IDE to re-use much of the old code, without recompiling.

Here's a rough idea:

#include <heltec-eink-modules.h>

// Pick your display model:

// EInkDisplay_WirelessPaperV1_1 display;
// EInkDisplay_WirelessPaperV1 display;

void setup() {
    display.landscape();

    display.print("Hello, World!");
    display.update();

    delay(2000);
    
    display.clearMemory();
    display.printCenter("Centered Text");
    display.update();

    delay(2000);

    display.clear();
}

void loop() {

}

Things to know

VExtOn()

The display, and wireless hardware, have an ACTIVE LOW power switch on GPIO45. The heltec-eink-modules libary will switch this on when first required.

If needed, you can manually power on the hardware with Platform::VExtOn().

Deep Sleep

In order to achieve the promised 18uA deep sleep current, a number of config steps must take place.

Calling Platform::prepareToSleep() will hopefully take care of this for you.

// Configure hardware for low-power
Platform::prepareToSleep();

// How long until restart
esp_sleep_enable_timer_wakeup( SLEEP_TIME_IN_MICROSECONDS );

// Sleep now
esp_deep_sleep_start();

The 18uA current is only achievable when powering with the battery connector. When USB is connected, an orange LED remains on.