$4 Wemos D1 mini ESP8266 Board Supports Shields with a Temperature Sensor, a Button, a Relay, or a micro SD slot

Wemos D1 board, a $9 ESP8266 board in Arduino UNO form factor, now has a little brother with Wemos D1 mini. The board looks somewhat similar to NodeMCU with breadboard friendly I/Os on the sides and a micro USB port for power and programming, but what could make it more interesting, beside the $4 price tag, is that the company also developed several shields (aka add-on boards).


Wemos D1 mini specifications:

  • WiFi 802.11 b/g/n module based on ESP8266EX with 4MB flash
  • Expansion – Through holes with
    • 11x digital input/output pins (3.3V) supporting interrupt/PWM/I2C/one-wire (except D0)
    • 1x analog input (3.3V max input)
    • Reset and power signals (5V, 3.3V, GND)
  • USB – micro USB port
  • Misc – Reset button
  • Power – 5V via micro USB or 5V pin
  • Dimensions – 34.2 x 25.6 mm
  • Weight – 10 grams

The board is said to be compatible with Arduino IDE and NodeMCU firmware. ESP8266 analog input only support 1 volts, but the board support 3.3V because a resistor voltage divider is included in the circuit. Schematics are always a good thing to have, as well as decent documentation.

Wemos_D1_mini_boardThe company also designed 5 shields adding temperature and humidity sensors with either DHT11 or DHT22 (wider range and more precise), a user button, a relay (3A or 5A @ 250V, 10A @ 125V), or a microSD. A third party shield has also been designed for prototyping.


Wemod D1 mini and DHT11 Temperature & Humidity Shield
Wemod D1 mini and DHT11 Temperature & Humidity Shield

You can order Wemos D1 for $4, and the shields for between  $0.99 and $4.90 on Wemos Aliexpress store. All these prices include shipping, how amazing is that? You can also find it on eBay for about $6. By the way, the latest revision (R2) of Wemos D1 Arduino UNO compatible board now sells for $6.50 shipped. 🙂

Thanks to Zoobab for the tip.

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8 years ago

BTW this board is breadboard friendly, it leaves a free row when plugged on a breadboard, not like the 3USD module you wrote about here:


With the wicloud one, you need two mini-breadboards to be able to play with it. It is annoying when you see they could have saved some space on the side.

8 years ago

Just noticed they had MicroSD shields:


Just wondering if there is some ESP code to use microsd cards with for ex vfat, or other filesystems, like espfs.

8 years ago


Rob Fowler
Rob Fowler
8 years ago

This would be a great reference platform for the “new” ESP micropython port. The kickstarter passed the 15K goal for support of a bunch of devices (my port already supports all the devices for this board but I will probably abandon or merge anything in theirs to mine so we have a common API). My interrupt time DHT22 driver has been running for 3 months non stop now. It is a fantastic combo.

8 years ago

Micropython allows IO from/to MicroSD:

Try this example:
# filesystem
import os

# list root directory

# print current directory

# open and read a file from the SD card
with open(‘/sd/readme.txt’) as f:

Not sure if the ESP8266 port will do this with this shield though….

Khadas VIM4 SBC