Paper WiFi

WiFi/BLE-enabled low power e-paper display devboard

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The Paper WiFi devboard is the ultimate tool for low-power, open-source projects that require a long-lasting sensor data display. This devboard combines WiFi and Bluetooth connectivity with an e-paper display, making it perfect for a wide range of applications.

At the core of the Paper WiFi devboard is the ESP32C3 microcontroller, known for its low power consumption and high performance. The devboard also includes an onboard relative humidity sensor, allowing it to measure the humidity and temperature of the surrounding environment. This makes the Paper WiFi devboard ideal for projects such as sensor monitoring and home automation.

The Paper WiFi devboard's e-paper display is perfect for projects that require a high-visibility, low-power display. With a resolution of 212 x 104 pixels, the display is capable of displaying text and simple graphics.

The whole design including electronics, firmware and mechanical is open source, available at github repository provided below.

The board has been designed with low power as a priority. Both hardware and firmware solutions are specifically tailored to support that.

Bare board deep sleep current

Averages at 34uA

Deep sleep current with GDEW0213T5D display

Averages at 41uA

Deep sleep current with GDEY0213B74 display
Averages at 52uA

Display update current with GDEW0213T5D display

Full display update takes 3.7s taking 97mC.

Display update on GDEY0213B74

Full display update takes 2.9s taking 68mC.



Adobe Portable Document Format - 618.21 kB - 03/03/2023 at 13:06


  • Firmware overview

    Albertas Mickėnas03/09/2023 at 19:41 0 comments

    Fully functional firmware supporting low power operation is provided and can be found in the github repository.

    Since we are using deep sleep, all the action happens in the setup function, only few state bytes are kept in RTC memory that is retained between wakeups:

    void setup() {
      Serial.println(String("Hello, is_first_run:") + is_first_run);
      SensorReadings new_readings = SensorsRead();
      if (is_first_run) {
        sensor_readings = new_readings;
      if (is_first_run || sensor_readings != new_readings) {
        DisplayData(new_readings, is_wifi_connected);
        Serial.println(String("is_wifi_configured:") + is_wifi_connected);
        if (is_wifi_connected) {
        } else {
          Serial.println("Wifi not connected");
        sensor_readings = new_readings;
      is_first_run = false;

    WifiManager library is used to support WiFi credential provisioning. 

    GxEPD library is used to access the display.

    Examples available:

    • Basic display test
    • Basic I2C test
    • Full example of humidity monitor, includinf WiFi provisioning and posting to MQTT
    • Full example of soil moisture monitor, includinf WiFi provisioning and posting to MQTT
    • Weather forecast example
    • BLE peripheral example

  • Design walkthrough

    Albertas Mickėnas03/03/2023 at 14:52 0 comments

    ESP32C3 supporting components is basically just following ESP32­C3 Family Hardware Design Guidelines. There's a footprint for 32kHz crystal, but since it's not supported in Arduino environment, also pins are broken out as GPIO.

    Display power conditioning circuit is also provided in a datasheet from GooDisplay

    Power section is designed to take in both USB and battery power. U5 is a boost converter and Q3 is responsible for disconnecting batteries when powered form USB and provide reverse polarity protection.

    Power to I2C sensors is switched via transistor to save some Coulombs 

  • Add WiFi

    Albertas Mickėnas03/03/2023 at 14:40 0 comments

    So I have decided to add WiFi to my display. It will not compromise display part, but will make it a more versatile tool for my sensor experiments. Also it adds another dimension to the project - it can not only display sensor data, but also whatever data pulled from the net!

    I have chosen ESP32C3 as the main micro-controller because of two reasons - it's low power and it's risc-v based - I wandered how good risc-v support is in the standard Arduino tool chain. Also ESP32C3 has in build USB-to-serial peripheral saving the need to design in USB-to-serial converter chip.

    Unfortunately, 2450 batteries had to go as they couldn't support high current spikes during WiFi communication. Thus AA batteries had to come in. I hesitated a bit between AA and AAA, but opted for AA to have more juice, meaning more communication and more display updates.

    I have chosen to use bare ESP32 chip and add printed 2.4GHz antenna to the PCB mainly to use this as an opportunity to learn something, also I didn't want to change the size of the PCB a lot and module is a bit bulky. I still have to go to RF lab to perform antenna measurements, I have just ordered bare PCBs with U.fl connector added for this specific task.

  • So I needed a display for sensor data

    Albertas Mickėnas03/03/2023 at 13:46 0 comments

    Sometimes having sensor data piped over RF to your database or to your console is not enough. Sometimes you want a big display displaying your numbers you could just throw a look at. Sometimes you want to package your sensor and a display to a person at industrial facility so they could quickly measure something without involving connectivity and computer.

    Thus 2 years ago I started on a journey to design myself a display like that. The device had to be battery operated - wall plug devices are a thing of the past, so e-paper was an easy choice for the display technology - low power, high contrast, relatively high resolution.

    I am not very good at mechanical design, so I wanted to piggyback on something that's available, thus I stumbled on electronic label enclosure kit available from GooDisplay

    This case has features allowing for two 2450 coin cell batteries, I hoped to sneak in whatever sensor wires I need via strategically drilled hole.

    So I have designed a PCB specifically for this case.

    On the top left you can see e-paper display power related components. Top right is a boost converted for voltage regulation and bottom right is an ATSAMD21G18A micro-controller. The choice for the micro-controller was mainly steered by availability and good software support available from Adafruit for their feather boards - I wanted to take advantage of that.

    After finishing the design I put it on a shelf as pandemic was in full swing, so I had another things to worry about, but after some time I came back and had another look - all this effort for just adding a display? Maybe I could beef it up somehow with additional functionality?

View all 4 project logs

  • 1
    Basic MQTT setup and testing

    Check out the tutorial here: Getting started with MQTT

  • 2
    Set up your own data collecting infrastructure with a few key presses

    This repository contains everything you need to set up InfluxDB, Mosquitto, Telegraf and Grafana to collect and display your data. Everything is pre-configured and ready to go. Easy IoT data infrastructure setup via docker

View all instructions

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zyndram wrote 03/12/2023 at 19:10 point

please add mesh network for example BATMAN

and create a emergency network on wifi

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