The HUZZAH32 Feather Board is ESP32-based development board from Adafruit. The HUZZAH32 comes equipped with pre-assembled headers, built in USB-to-serial converter, automatic bootloader reset, lithium ion/polymer charger, and nearly all of the GPIOs exposed.

Project Specifics

Having both BLE and Wi-Fi connectivity options, HUZZAH32 projects include the following protocol elements:

BLECharacteristicElement icon for the element library

BLE Characteristic

BLEConnectionElement icon for the element library

BLE Connection

Wi-FiConnectionElement icon for the element library

Wi-Fi Connection

As is standard with any project type that uses Wi-Fi, cloud elements are accessible from both the Embedded and Application tabs in Atmosphere Studio.

Hardware Specifics

Some devices may have limitations or design restrictions that cause unexpected behavior when used with Atmosphere. Specific information and details pertaining to the HUZZAH32 and its performance on Atmosphere is noted below.

  • ADC2 is not accessible, since it conflicts with the Wi-Fi. This means that pins IO4, IO0, IO2, IO15, IO13, IO12, IO14, IO27, IO25, and IO26 cannot be used as analog input pins.

Default Pin Mapping

Atmosphere configures each peripheral to a default pin for every supported device, based on ideal pairing of pins and their usage. The default pin configuration is set for convenience and enables each peripheral to work naturally without needing to be modified.

All pins can be used as general purpose input/output (GPIO) unless otherwise specified.

HUZZAH32 projects start with the following pin configuration:

Pin Table

Pin Description Notes
ESP32_UART1_TX UART1 TX Pin Maps to IO17
ESP32_UART1_RX UART1 RX Pin Maps to IO16
ESP32_UART2_TX UART2 TX Pin Maps to IO1
ESP32_UART2_RX UART2 RX Pin Maps to IO3
ESP32_I2C_SDA I2C SDA Maps to IO23
ESP32_I2C_SCL I2C SCL Maps to IO22
A0 Analog Connector A0 Maps to IO26
A1 Analog Connector A0 Maps to IO25
A2 Analog Connector A0 Maps to IO34
A3 Analog Connector A0 Maps to IO39
A4 Analog Connector A0 Maps to IO36
A5 Analog Connector A0 Maps to IO4

Internal ESP32 Pins

All internal pins can be accessed using the following nomenclature: IO[PIN] OR GPIO_NUM_[PIN]. For example, pin 12 can be accessed via IO12 or GPIO_NUM_12.

The default pin for any peripheral can be changed within an element's properties, from an element that references that particular peripheral.


Below is information regarding the HUZZAH32’s exposed peripherals.



This I2C bus is exposed via pins IO23(SDA) and IO22(SCL).



This SPI bus is exposed via pins IO18(MOSI), IO19(MISO), and IO5(CLK).


UART1 (USB Debug Console)

This UART is exposed via the micro-USB connector on the HUZZAH32 or pins IO17(TX) and IO16(RX).


This UART is exposed via pins IO1(TX) and IO3(RX).


ADC2 cannot be used, since it conflicts with the Wi-Fi. The following pins can be used for analog input:

  • IO36
  • IO37
  • IO38
  • IO39
  • IO32
  • IO33
  • IO34
  • IO35


Any GPIO pin can be used for PWM output.

Programming Method

Programming the HUZZAH32 involves using the programmer interface in Atmosphere Studio to install embedded firmware.

Setup Configuration

Prior to programming an HUZZAH32, ensure you have the following setup configuration:

  • The HUZZAH32 is connected to the computer via USB to an available communication port.
  • The computer has the necessary connectivity protocols enabled (Bluetooth Low Energy, Wi-Fi, etc.).
  • The Atmosphere IoT Agent is installed on the computer and running. This is a local application that runs in the system tray and acts as an intermediary between the computer’s connectivity protocol drivers and the browser running Atmosphere.
  • An Internet connection is maintained.
  • The project to be programmed has been compiled.

Programming Instructions

With setup complete, you can program the HUZZAH32:

  1. From Atmosphere Studio’s Embedded tab, click the Program Firmware button from the tab’s toolbar. This displays the Program Firmware window.
  2. Under Device Port, select the communication port the device is connected to.
  3. Click Program to start programming. When complete, you’ll be notified that the device is programmed with the project’s embedded firmware.

When complete, the HUZZAH32 is programmed with the project’s embedded firmware.

Guides and Tutorials

Get started using the HUZZAH32 with Atmosphere by walking through the following guides:

HUZZAH32 Guides
Getting Started with ESP32
Creating a Zigbee Mesh Network with Atmosphere

Demo Projects

Atmosphere includes a variety of HUZZAH32 demo projects for users of all levels. Check them out by clicking the demo’s name to open the project in Atmosphere.

Name Description
Control LED Over BLE Demo Control the device’s red LED by pressing a button in the app to toggle the color over BLE.
RegEx Element ESP32 Demo The function element is used within this demo project by giving an input a string via BLE using a button element and categorizing the string into non-alphanumeric, alphabet and numeral characters by checking if the string matches the regular expression pattern.
PWM Pin ESP32 Demo The PWM pin element is used within this demo project by increasing the brightness of the ESP32’s LED alongside counter and mathematical operation elements.
Data Type Conversion ESP32 Demo The data type conversion element is used within this demo project by reading the integer values from the app’s slider using BLE and converting them into characters from the ASCII table, then printing them on the debug console.
Comparison ESP32 Demo The comparison element is used within this demo project by taking values from the app’s slider using BLE, comparing those values, then printing them on the debug console.
ADC Pin ESP32 Demo The ADC pin element is used within this demo project by reading the voltage from the analog pin and sending the data to the cloud.
Digi XBee3 Zigbee Receiver Demo Demonstrates the Digi XBee3 Zigbee module by having the HUZZAH32 act as the coordinator of a Zigbee network and forward received data to the Atmosphere cloud. Designed to work with the Digi XBee3 Zigbee Sender Demo.


The following additional resources and downloadable files are available for the HUZZAH32: