Unpacking the Wemos D1 R2, ESPDuino clone, ESP8266 development board in Arduino Uno format

The Arduino Uno is the reference for development boards to start learning programming. The Arduino Uno is an ideal learning platform because it does not cost much and you can learn to code on concrete projects. What better than to see his robot move. There are also many daughter cards that are often found under the name Shield. There are shields to add WiFi connectivity, Bluetooth or Ethernet but these boards are very expensive. The ESP8266 (and its successor the ESP32) fills this gap. The WiFi module ESP8266 is able to run Arduino code in C++, has 11 inputs / outputs (all PWM) and an analog input (3.3V max.). Manufacturers quickly realized the value of offering Arduino Uno boards based on ESP8266 modules to be compatible with all existing shields.

ESPDuino or Wemos D1 R2

ESPDuino is the oldest ESP8266 development board in Arduino Uno format. It was quickly cloned and is now found at Doit.am (former Geekcreit). At Wemos, it is called Wemos D1 R2.

These cards are in almost identical. The difference will mainly reside at the USB connector (type A for ESPDuino or micro-USB on the Wemos). The Serial to USB converter may also be different. You may need to install the corresponding drivers. In general it is a CH34O or CH341. If you’re having trouble, follow this tutorial (in French at the moment) to install it on your environment.

Differences can also be found in the ESP8266 module. The Wemos is built around an ESP-12 while the SPDuino ships an ESP-13 (ESP-WROOM-02 from Espressif). Both modules have 4 MB of flash memory and 64 KB of RAM. From the point of view of the end user (who we are), we can consider the two modules as identical, and therefore the two development boards. For the most demanding of you, know that Espressif has completely taken over the designation of his cards recently. They all now bear the same name ESP8266EX. In the medium term, when the manufacturers have exhausted all their stock of modules, there will be only 4 models with small optimizations. All the details are here.

  • ESP-WROOM-02, operates from -40 ° C ~ 125 ° C. Low dimension 18x20x3 mm with PCB antenna
  • ESP-WROOM-02D, the PCB antenna is optimized for better WiFi reception
  • ESP-WROOM-02U. The module is even more compact (18Xx14.3×3.2mm). The PCB antenna is replaced by an external antenna connector to U.FL IPEX standard.
  • ESP-WROOM-S2. This module can operate as an SDIO / SPI slave with a bus speed of up to 8 Mbps.

Attention to GPIO that works with a voltage of 3.3V

Special feature of the ESP8266 compared to the Arduino Uno (this is no longer the case for the Genuino 101 and new Intel Curie-based cards), the GPIO operates at a voltage of 3.3V. It will therefore in some cases adapt your editing. For this, there are voltage dividers (5V to 3.3V) or vice versa (3.3V to 5V). The only analog input is also limited to a maximum voltage of 3.3V.

We will use the Wemos D1 R2 in the next tutorials on robotic arms. If you’re new to Arduino / ESP8266 programming, you can start with this article. You will learn how to install the ESP8266 libraries and SDK on the Arduino IDE. You will also learn how to use GPIO and WiFi libraries. You will see how to create an HTML interface to your Arduino projects and communicate with a home automation server using HTTP requests. If you have taken a liking to the programming of micro-controllers, here are the latest tutorials published on the subject:

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