ESP8266 ESP-201 Dev board

Posted on Apr 17, 2015 by HappyBison

ESP8266 Dev board around ESP-201 module

I recently came across ESP8266 WiFi chip and various modules based on it. This is a low cost microcontroller with WiFi built into it. There is a huge community around ESP8266. You can develop for it using C, Lua and even Wiring using Arduino development tools.

I decided to get my hands on it to play with it a little. I ordered some boards for a start. First, I needed some kind of easy prototyping dev board for easier testing. I got ESP-201 and Dev board designed specifically for it. After unsuccessful search looking for schematic to see how GPIO pins connected on it, I decided to trace it and make my own to share with others.

esp8266-esp201-sdk-dev.png

I traced it as much as I could, but it may have some bugs. If you find something, feel free to let me know. Update: I found similar schematics after I created my version, so I'll keep it here anyway.

Interesting thing is that CH340G is powered using 5V power and connected to RX/TX of ESP-201 module without any level shifters. At first, I did not know it and was able to test the board. So it seems like RX/TX are 5V tolerant after all.

Board features

The board has the following:

  • USB Mini: power and serial communications
  • USB Micro: power only. One USB can be connected at a time, not both
  • AMS1117 3.3V LDO (capable up to 1A)
  • Power on/off switch
  • CH340G USB-RS232 bridge. You can by-pass it by using JP4/JP7 jumpers and JP2 connector
  • Boot mode S2/S3 switches
  • Switch block to connect/disconnect various load (LED, Relay, etc)
  • RGB Led, White LED, Buzzer, Relay, Pot, DHT11 connector

The LEDs are very bright so I had to use PWM to lower the brightness.

Connections

Here is the connection table of all peripherals on the board:

Pin

Connection

GPIO 0

S2 switch

GPIO 2

S3 switch

GPIO 4

DHT11

GPIO 5

Buzzer

ADC

Multi-turn pot

GPIO 12

RGB (B) LED

GPIO 13

RGB (G) LED

GPIO 14

White LED

GPIO 15

RGB (R) LED

GPIO 16

Relay

Additionally, the switch block has K1 linking ground to GPIO 15, and K2 linking ground to GPIO 0 (for bootloader).