DoorsignEPD-pcb

ESP-WROOM-32 breakout board to connect it to a Waveshare E-Ink display.

Inspired by article Ausdauernde Infotafel from German computer magazine c't. Example arduino and server software can be found here.

Input voltage is connected to a voltage regulator jack and directly to Pin6/IO34/ADC6 for monitoring. Hence input voltage must be below 3.6V. I use 2xAA together with a step up regulator. Additionally I connected a pad for Pin8/IO32/ADC4/TOUCH9. Haven't used it yet. Maybe for a touch wakeup or status LED.

Display connector pin assignment is identical to the Waveshare hat connector.

Rev A2 PCB can be ordered e.g. via aisler.net: https://aisler.net/p/HSIWEKKI

Components needed in addition to PCB:

• Of course an ESP-WROOM-32 (or footprint compatible)
• Waveshare E-Ink display
• 3.3V voltage regulator or other 3.3V source
• Battery + holder of your choice
• 2x ~10kΩ pullup resistors R1+R2
• 2x tactile switch (included in aisler precious parts)
• 1x JST-PH 8 connector header+housing (included in aisler precious parts)
• 1x JST-PH 2 connector header+housing (included in aisler precious parts)
• 10-15 JST-PH terminals (included in aisler precious parts)
• Crimp tool for JST-PH connectors
• 3.3V capable USB-TTL adapter for programming

Programming

This a minimalistic board to save power. No USB included. So you need an USB-TTL adapter that is capable of doing 3.3V. This one works for me under Linux.

To upload an arduino sketch/flash firmware:

1. Connect the USB-Adapter GND/RX/TX to the board. Most adapters need RX board/TX adapter and TX board/RX adapter. If that doesn't work try RX/RX+TX/TX. To check press the Reset button. The serial monitor must show the ESP33 boot log.
2. Press and hold the Boot(loader) button, shortly press the Reset button, then release the Boot button. Log should show the ESP32 entering bootloader mode.
3. Now stop any serial monitor (Arduino IDE does this automatically)
4. Upload the sketch and wait until completion
5. Again press the Reset button
6. Restart serial monitor (Arduino IDE does this automatically)

Assembled board

Changelog

Rev A2 (minor)

• Trace width power supply + GND
• Via min size 0.65mm (=drill + 0.25mm)

Rev A1

• Initial revision