Hi. Today I explain about the esp8266 module for my project. The esp8266 is very famous cheap microcontroller has the Wi-Fi function. There are any types of module. ESP12 is popular module in the world.

But I have chosen ESP-WROOM-02 because it needs to pass the TELEC certification to use in japan.

Esp8266 module needs power converter and USB-serial converter when it run and writes the program. The ESP-WROOM-02 Developer Board is easy way to develop because it has these functions.

The NodeMCU is popular in the world. May be the functions are same.

The added circuits


The reset

I added external circuits for the reset on ESP-WROOM-02 Developer Board. The register and capacitor tied to EN pin and the capacitor tied to RESET pin for power on reset. The RESET pin has a pull-up register on the developer board yet. So it was added only capacitor at the RESET pin. The IO16 tied to RESET pin throw the register (470 ohm). It needs to wake it up from the sleep.


Esp8266 has a few GPIO pins. The EPD needs many pins for control and data transfer. So I added shift register for extend Output pins. I explain the details later.

The voltage regulator

The ESP-WROOM-02 Developer Board has a voltage regulator to convert from the USB 5V to 3.3V for ESP-WROOM-02 module. The esp8266 needs large power consumption often. This power ability is not powerful so much to supply for other devices (shift register and SD card). And the USB 5V voltage is dropped down lower 4V throw the USB cable and when the esp8266 is running. The voltage regulator was required the low dropout (LDO) voltage regulator.


Next I will share the Power block.

Thanks reading.


Contents of the EPD project