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Pinout of the ESP8266 SoC and ESP12E module

We are going to continue delving into the ESP8266 SoC from manufacturer Espressif. In this post, we will see the pinout scheme of the ESP8266 and ESP12E.

One of the first difficulties when using development boards based on the ESP8266 is obtaining their pinout scheme. Even more so because manufacturers do not maintain the same criteria when assigning the board pins to those of the ESP8266. This can lead to more than one headache.

That’s why it’s important to spend some time understanding the pins and hardware of the ESP8266. Because, even if the designations change on the development boards, they will always have in common the characteristics of the ESP8266, so that only by knowing the equivalence between the pins, we will be able to use any development board.

On the other hand, the ESP12E is the most widely used module with ESP8266 SoC in development boards. Understanding its pinout is closely related to understanding the ESP8266, disregarding pins that do not provide much value (internal).

Finally, understanding the pinout and hardware of the ESP8266 and the ESP12E will allow us to use them independently, without a development board. Although we will have to include our own electronics (resistors, dividers, voltage regulators).

So let’s start delving into the hardware of the ESP8266 and the ESP12E module, looking at their pinout, and then we will see some details of their hardware.

ESP8266 Pinout

Here is the pinout scheme of the ESP8266.


The ESP8266 has 32 available pins, of which 17 are GPIO, 1 is an ADC, and the rest are essentially related to the power supply and control of the ESP8266.

ESP12E Pinout

On the other hand, here is the pinout scheme of the ESP12E.


As we can see, the ESP12E has 22 pins. It maintains the 17 GPIO pins, the ADC pin, but reduces the power supply pins to 2 (Vcc and GND) and the control pins to CHIP_EN (turn on/off the ESP12E) and EXT_RSTB (to reset).

That is, in the ESP12E, we have most of the “important” pins of the SoC available, while the module is responsible for electrically connecting most of the power supply and control pins. This is one of the reasons for the success and high implementation of the ESP12E, as it offers us all the functions of the ESP8266. Other modules, for example, like the ESP01 or even the ESP12S, which do without some GPIO to have a smaller number of pins or a smaller size.

In the next post of the series on ESP8266 and ESP32, we will go into detail on the hardware of the ESP8266 and see the main differences with the usual Arduino models that integrate the ESP8266 and we will start their programming.