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Recently a test board for the ESP8266 ESP-12 arrived. I ordered it on AliExpress
and took several weeks to arrive. Since the description was really bad I had to reverse engineers the functions and pins:
|Pin layout of the test board
As you can see the board comes with a ready soldered ESP8266 ESP-12 soldered to it and all the pins are available to the left and right of the ESP-12 board. In addition the TX, RX and GND are available at the bottom of the board. There is also a jumper which you close for programming the firmware and open to run the firmware.
There are also 6 red leds fixed with the necessary resistors connected to GPIO16, GPIO14, GPIO5, GPIO4, GPIO0 and GPIO2. A blue LED is always on if the board is powered.
The GPIO13, GPIO12 and GPIO15 are connected to a RGB LED which allows you color mixing using PWM.
The analog-digital converter is also available on a pin but it is also connected to a light resistor. This lets you quickly test the ADC and you still can clip the resistor off if you want to measure another analog source.
it took me a little while to figure out that the range of the ADC is not 0..3.3V but 0..1V, so make sure that the voltage you plan to measure is in this range.
The test board comes with a batterie pack attached which takes 3 AA cells. In the following test scenario the board ran 39 hours:
- running nodemcu lua firmware
- all but the blue power LEDs were off
- a DHT11 connected to measure temperature and humidity
- all 10minutes posting temperature and humidity to thingspeak.com
- no deep sleep used
|Test setup with DHT11 ran 39hours, posting
every 10min to thingspeak.com
The test board is a good and easy way to get started with the full range of available functions on the ESP8266. Especially to develop a firmware and check pin functions it comes in very handy. If you don’t want to use the light sensor or the LEDs you can simply clip them off. Then you’ll just have a priceworthy ESP8266 with 3xAA power supply, 9 available GPIO pins and one ADC.
Update – Pimp my power supply
If you prefer USB power supply over the battery pack then you can change that with just a little bit of soldering. Take an old USB wire and cut it with appropriate length. My wire had white, yellow, red and black wires. Assuming that red is +5V and black is GND I used my volt meter to check that it was correct. Then I removed the battery pack and soldered the black and red wire instead. Don’t worry about the 5V of the USB connector compared to the 4.5V of the serially connected batteries: There is a power regulator of type HT7333 which regulates the 5V down to a pleasant 3.3V.
|Test board after replacing the battery pack
with a USB wire
A ridiculous amount of coffee was consumed in the process of building this project. Add some fuel if you'd like to keep me going!