Development board prototype
A development board prototype is a very fast, cheap, and convenient way to do a proof-of-concept test of the wall-ink firmware and wall-ink-server software, without having to source all of the individual components and solder them together. The development board has all of the same capabilities of the full wall-ink device hardware except the ability to use little or no battery power when in deep-sleep. The development board can deep-sleep, but has a built-in USB to serial chip that consumes a constant 20mA, as well as the power used for the indicator LEDs, etc that will drain batteries quickly. An ESP8266 development board is powered by USB, costs $5-$10 (US) and requires no soldering.
When ordering an ESP8266 development board, make sure to get an ESP-12 module. There are many flavors of ESP8266, but wall-ink was designed to run only on an ESP-12, and tested specifically on the ESP-12F.
You will also need a Waveshare e-ink screen. The wall-ink firmware and wall-ink-server software were designed to handle multiple size screens, but much of the deveopment focused on handling the 7.5 inch screen size. The 7.5 inch Waveshare screen will come with the screen, a HAT, a ribbon cable extender, some mounting hardware for the HAT and a JST PH 2.0mm breadboard breakout cable as seen below. This breakout cable is very handy to plug the HAT directly into the pins of the development board as seen in the picture above.
The image below shows the color-coded wiring needed to interface the development board with the e-ink HAT. The switch and the 470 ohm resistor are only needed to use Admin mode. The 470 ohm resistor with the cyan/blue wire is used to bring the esp8266 out of deep sleep.
The image below shows all of the minimum parts hooked together to make a wall-ink prototype. You can use a breadboard if you want, but it will require more parts, like additional wires and header pins since the Waveshare HAT breakout cable has female connectors, and the ESP8266 typically almost completely fills a breadboard.
| Quantity | Item | Notes | Example supplier |
|---|---|---|---|
| 1 | ESP8266 (ESP-12) development board | ||
| 1 | 7.5 inch Waveshare e-ink screen | ||
| 1 | A couple of wires, a SPST switch, and a 470 ohm resistor | You can see in the picture directly above, I didn't bother using a switch, and just held the resistor on the wire for a few seconds to access Admin mode. This resistor, switch, and the wire are only needed to access Admin mode. | |
| 1 | 470 ohm resistor | This 470 ohm resistor is used to wake up the ESP8266 from deep sleep. | |
| 1 | Micro USB cable | Used to both power the development board and used to flash the firmware onto the ESP8266 through the Arduino IDE on a PC. |