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Introduction to ESP32 GPIO

The ESP32 chip features forty physical GPIO pads. Some GPIO pads cannot be used or do not have the corresponding pin on the chip package. For development boards based on the ESP32 chip or module, some board makers probably expose all ESP32 GPIO pins. However, some board makers also expose ESP32 GPIO pins but add additional pins such as battery, voltage, exclusive sensor, and ground.

Since there are many ESP32 development board models, we cannot explore all board models. Instead, we will focus on the ESP-WROVER-KIT board from Espressif.

We can access GPIO pins on the ESP-WROVER-KIT board with three locations. You can see these locations from the ESP-WROVER-KIT board in the following image. Some GPIO labels are shown in the board body so that we can see all of the GPIO pins:

Figure 2-1: GPIO pins from an ESP-WROVER-KIT board

Some GPIO pins are used for PWM, ADC, DAC, I2C, I2S, and SPI. You can find this GPIO layout from the ESP-WROVER-KIT board in the following document: https://dl.espressif.com/dl/schematics/ESP-WROVER-KIT_V4_1.pdf.

Now that we've picked a board on which to work, let's get a brief overview of IoT for weather monitoring systems before we begin setting one up.