Introduction

A pin on an Arduino-core device can be configured to operate in one of several modes.

For example, a digital pin may be configured for input, output, and some digital pins may be used for analog output (PWM) operation.

Analog input pins are even more flexible. They may be configured for analog input, digital input, or digital output operation.

Arduino Brand MCUs

Arduino board pin-numbers are specified using a modified version of standard Arduino pin-numbers.

Digital Pin Numbers

Digital pin-numbers are specified using a single integer value, such as 3 for digital pin 3.

Analog Pin Numbers

Analog pin-numbers are also specified using a single integer value using the analog pin-number without the "A." For example, pin A4 is identified simply as 4.

ESP-8266

Digital Pin Numbers

The ESP-8266 digital pin-numbers are mapped using the GPIO pin-number mapped according to the variants file for a specific board in the ArduinoCore for the ESP-8266.

Using a NodeMCU as an example, to use D2, its GPIO pin-number is 4.

Analog Pin Numbers

The ESP8266 has a single Analog input pin, and it is specified as pin 0.

STM32

Digital Pin Numbers

The STM32 digital pin-numbers are mapped using the GPIO pin-number mapped according to the variants file for a specific STM32 shown in the STM32 Arduino Core. Using the BlackPill MCU as an example, the pin marked as B3 on the board is specified as 19.

Analog Pin Numbers

Analog pin-numbers are specified in the range of 0 to 15. The variants file shows how those values are mapped as described in the specific variants file for each MCU.

SPI Pins

Telemetrix uses the standard SPI pins as mapped in each specific variants file.

I2C Pins

Telemetrix uses the standard I2C pins as mapped in each specific variants file.