Overview

The Adafruit Circuit Playground Express is an all-in-one educational microcontroller board designed to make electronics and programming accessible to beginners while providing enough capability for advanced projects. It features numerous built-in sensors, LEDs, buttons, and a speaker, all on a single round PCB that’s perfect for wearables and interactive projects.

Hardware Features

• Microcontroller: ATSAMD21 ARM Cortex M0+ Processor
• Clock Speed: 48 MHz
• Operating Voltage: 3.3V
• Flash Memory: 2 MB SPI Flash storage
• Built-in Components:
  • 10 × RGB NeoPixel LEDs - Individually addressable, full color
  • 1 × Motion Sensor - LIS3DH triple-axis accelerometer with tap/free-fall detection
  • 1 × Temperature Sensor - Thermistor
  • 1 × Light Sensor - Phototransistor (can detect color and pulse)
  • 1 × Sound Sensor - MEMS microphone
  • 1 × Mini Speaker - 7.5mm magnetic speaker/buzzer with Class D amplifier
  • 2 × Push Buttons - Labeled A and B
  • 1 × Slide Switch - On/off switch
  • Infrared TX/RX - Receiver and transmitter for remote control and proximity sensing
  • Green “ON” LED - Power indicator
  • Red “#13” LED - Standard blinky LED
  • Reset Button
• I/O Pins:
  • 8 × Alligator-clip friendly pads
  • I2C support
  • UART support
  • 8 pins with analog input capability
  • Multiple PWM outputs
  • 7 pads with capacitive touch input
  • 1 true analog output pad
• USB: Micro-USB port for programming and debugging
  • Can emulate serial port, keyboard, mouse, joystick, or MIDI device
• Power: USB or 3 × AAA battery pack (sold separately)
• Form Factor: Round PCB, 2” (50mm) diameter
• Mounting: 4 mounting holes for securing

The Circuit Playground Express uses the ATSAMD21 (ARM Cortex-M0+) microcontroller, which is not supported by ESPHome.

Built-in Sensors and Components

• NeoPixel LEDs (10×)
• Accelerometer (LIS3DH)
  • I2C address: 0x19
• Temperature Sensor
• Light Sensor
  • Ambient light detection
  • Can also function as:
    • Color sensor (with NeoPixels)
    • Pulse sensor (heart rate monitoring)
• Sound Sensor (MEMS Microphone)
  • Not for voice recording
• Speaker
  • 7.5mm magnetic speaker
  • Plays tones and simple melodies
  • Class D amplifier
  • Volume control in software
• Infrared TX/RX
  • Send and receive IR signals
  • Compatible with TV remotes
  • Proximity sensing capability
• Buttons and Switch
  • 2x Programmable input buttons
  • 1x Slide Switch
  • 1x Reset Button

Pin Layout

The Circuit Playground Express has 8 main pads around the edge, all alligator-clip friendly:

Pad	Functions	Notes
A0	Analog In, PWM, Capacitive Touch	Audio output capable
A1	Analog In, PWM, Capacitive Touch
A2	Analog In, PWM, Capacitive Touch
A3	Analog In, PWM, Capacitive Touch
A4	Analog In, PWM, Capacitive Touch, I2C SDA
A5	Analog In, PWM, Capacitive Touch, I2C SCL
A6	Analog In, PWM, Capacitive Touch, TX	UART TX
A7	Analog In, PWM, Capacitive Touch, RX	UART RX

Additional Pads

• GND (3 pads) - Ground connections
• 3.3V - 3.3V power output
• VOUT - Battery voltage output

Capacitive Touch

7 of the 8 pads (A1-A7) support capacitive touch sensing:

• Touch with finger to trigger
• No button press needed
• Can sense through thin materials
• Great for interactive projects
• Works with conductive materials (fruit, water, foil)

Power Options

USB Power

• 5V from Micro-USB port
• Most common for development
• Can power all features

Battery Power

• LiPo battery or 3 × AAA battery pack
• Connects to JST connector on back
• Portable operation
• Battery voltage available on VOUT pad
• Slide switch controls power

Power Considerations

• Current draw with all NeoPixels on: ~200mA
• Typical usage: 20-50mA
• Sleep mode: Available but varies by programming method