The Adafruit Feather M4 Express is a compact, feature-rich development board designed for versatility and ease of use. It is based on the ATSAMD51 microcontroller and is part of the Feather ecosystem, known for its portable and modular design. This board is ideal for a wide range of applications, from prototyping to final products, including IoT devices, wearable technology, and embedded systems.
Explore Projects Built with Adafruit Feather M4 Express
Use Cirkit Designer to design, explore, and prototype these projects online. Some projects support real-time simulation. Click "Open Project" to start designing instantly!
This circuit is designed for environmental data collection and logging, utilizing an Adafruit Feather M0 Express microcontroller as the central processing unit. It interfaces with a BME280 sensor for atmospheric temperature, humidity, and pressure measurements, an SGP30 sensor for monitoring air quality (eCO2 and TVOC), and a STEMMA soil sensor for detecting soil moisture and temperature. The system is powered by a solar panel and a 3.7v LiPo battery, managed by an Adafruit BQ24074 Solar-DC-USB Lipo Charger, and provides easy access to the microcontroller's connections through an Adafruit Terminal Breakout FeatherWing.
This circuit integrates an Adafruit MPR121 capacitive touch sensor with an Adafruit Feather 32u4 Bluefruit microcontroller. The MPR121 is powered by the Feather and communicates via I2C (SCL and SDA) to detect touch inputs, which can be processed or transmitted wirelessly by the Feather.
This circuit integrates an Adafruit MPR121 capacitive touch sensor with an Adafruit Feather 32u4 Bluefruit microcontroller. The MPR121 is powered by the 3.3V supply from the Feather and communicates with the microcontroller via I2C, with SCL connected to pin 3 and SDA connected to pin 2 of the Feather. This setup allows the Feather to detect touch inputs from the MPR121 for further processing or wireless communication.
This circuit is designed to interface multiple sensors with an Adafruit Feather M0 Adalogger microcontroller for data logging purposes. The sensors include a MAX30205 temperature sensor, a body dehydration sensor, a MAX30102 pulse oximeter, an Adafruit LSM6DSOX 6-axis accelerometer and gyroscope, and an Adafruit BME680 environmental sensor. All sensors are connected to the microcontroller via an I2C bus, sharing the SDA and SCL lines for communication.
Built-in 3.3V regulator with 500mA peak current output
Pin Configuration and Descriptions
Pin Number
Function
Description
1
GND
Ground
2
3V
3.3V power supply pin
3-8
A0-A5
Analog input pins or digital I/O
9-10
SCK, MISO
SPI communication pins
11-12
MOSI, SDA
SPI communication pin, I2C data line
13
SCL
I2C clock line
14-25
D0-D11
Digital I/O pins, PWM capable on D5, D6, D9-D11
26
RX
UART receive pin
27
TX
UART transmit pin
28
EN
Enable pin for the 3.3V regulator
29
BAT
Battery voltage (connected to battery connector)
30
USB
Native USB port
31
NeoPixel
Data input for the onboard NeoPixel LED
32
RST
Reset pin
Usage Instructions
How to Use the Component in a Circuit
Powering the Board: The Feather M4 Express can be powered via USB or a 3.7V LiPo battery. Ensure that the power source is connected properly to avoid damaging the board.
Connecting Peripherals: Use the GPIO pins to connect sensors, actuators, or other peripherals. Be mindful of the voltage levels and current capabilities of the pins.
Programming the Board: The board can be programmed using the Arduino IDE or other compatible software. Select "Adafruit Feather M4 (SAMD51)" as the board type in your IDE.
Important Considerations and Best Practices
Always disconnect the power source before making or altering connections.
Use a current limiting resistor when connecting LEDs to GPIO pins.
Avoid drawing more than 500mA from the 3.3V regulator.
Ensure that the battery is connected with the correct polarity.
Update the bootloader if necessary, following Adafruit's instructions.
Example Code for Arduino UNO
#include <Adafruit_NeoPixel.h>
#define PIN_NEOPIXEL 8 // Pin connected to the NeoPixel
#define NUMPIXELS 1 // Number of NeoPixels
// Initialize the NeoPixel library.
Adafruit_NeoPixel pixels(NUMPIXELS, PIN_NEOPIXEL, NEO_GRB + NEO_KHZ800);
void setup() {
pixels.begin(); // Initialize the NeoPixel strip
}
void loop() {
pixels.setPixelColor(0, pixels.Color(150, 0, 0)); // Set the pixel to red
pixels.show(); // Send the updated pixel colors to the hardware.
delay(500); // Wait for half a second
pixels.clear(); // Turn off the pixel
pixels.show();
delay(500);
}
Troubleshooting and FAQs
Common Issues
Board not recognized by computer: Ensure the USB cable is properly connected and the board is powered on. Try a different USB port or cable if necessary.
Unable to upload sketches: Check that the correct board and port are selected in the IDE. Ensure the bootloader is up to date.
Peripherals not working: Verify connections and ensure that the code is correctly written for the peripherals. Check power requirements and pin configurations.
Solutions and Tips for Troubleshooting
Reset the board: If the board is unresponsive, press the reset button twice quickly to enter bootloader mode.
Check solder joints: Poor soldering can lead to unreliable connections. Inspect and rework any questionable joints.
Consult the forums: The Adafruit forums are a valuable resource for troubleshooting specific issues with the Feather M4 Express.
FAQs
Q: Can I use the Feather M4 Express with a 5V system?
A: The board operates at 3.3V. Level shifting is required to interface with 5V systems.
Q: How do I charge the connected LiPo battery?
A: The Feather M4 Express has a built-in charging circuit. Simply connect the board to a USB power source, and it will charge the battery.
Q: What is the maximum current draw from a GPIO pin?
A: Each GPIO pin can source or sink up to 10 mA. However, the total current from all GPIO pins should not exceed 120 mA.
Open Project in Cirkit Designer
