The Adafruit Metro Mini is a compact, breadboard-friendly microcontroller board based on the ATmega328PB MCU. It is designed to be compatible with the Arduino IDE, allowing users to easily write and upload code to the board. With its small size and extensive I/O capabilities, the Metro Mini is ideal for projects that require a powerful yet space-efficient microcontroller. Common applications include wearable electronics, prototyping, educational purposes, and DIY projects.
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This circuit features an Arduino Pro Mini as the central microcontroller, interfaced with a DS18B20 temperature sensor, a GPS NEO 6M module for location tracking, an ADXL345 accelerometer for motion detection, and an NRF24L01 module for wireless communication. The Arduino is powered by a 18650 Li-Ion battery through a voltage regulator, ensuring a stable power supply. A pushbutton is connected to the Arduino for user input, and resistors are used for pull-ups and current limiting purposes.
This circuit features an Arduino Pro Mini as the central microcontroller, interfaced with a GPS NEO 6M module for location tracking, an ADXL345 accelerometer for motion sensing, a DS18B20 temperature sensor for environmental monitoring, and an NRF24L01 module for wireless communication. The circuit is powered by an 18650 Li-Ion battery through a voltage regulator, ensuring stable power supply to the components. A pushbutton is included for user input, and resistors are used for pull-up/down configurations and current limiting purposes.
This circuit features an Mtiny Uno ATmega328P microcontroller as its central processing unit, interfacing with a variety of sensors and peripherals. It includes a 0.96" OLED display and an MPU6050 accelerometer/gyroscope for user interface and motion sensing, respectively. The circuit also integrates a TF LUNA LIDAR for distance measurement, a DHT11 sensor for temperature and humidity readings, and uses a 9V battery with a 7805 voltage regulator for power management. Communication with a computer for programming and data exchange is facilitated by an Adafruit FTDI Friend module.
This circuit features two Arduino Pro Mini microcontrollers interfacing with various sensors and actuators. One Arduino reads data from an ADXL345 accelerometer and communicates with an RS232 module, while the other controls a 2-channel relay to manage two 12V LEDs, a 1-channel relay to control a red lamp, and a buzzer. Power is supplied by 9V and 12V batteries.
Digital I/O Pins: 20 (6 of which provide PWM output)
Analog Input Pins: 6
DC Current per I/O Pin: 20 mA
DC Current for 3.3V Pin: 50 mA
Flash Memory: 32 KB (ATmega328PB) of which 0.5 KB used by bootloader
SRAM: 2 KB (ATmega328PB)
EEPROM: 1 KB (ATmega328PB)
Clock Speed: 16 MHz
LED_BUILTIN: Pin 13
Pin Configuration and Descriptions
Pin Number
Function
Description
1
RESET
Used to reset the microcontroller
2-7
Digital I/O
Digital pins, PWM available on pins 3, 5, 6
8-13
Digital I/O
Digital pins, PWM available on pins 9, 10, 11
A0-A5
Analog Input
Analog input pins
A4, A5
I2C
SDA and SCL for I2C communication
A6, A7
Analog Input
Additional analog input pins (not on headers)
14 (TX)
Serial TX
Transmit pin for serial communication
15 (RX)
Serial RX
Receive pin for serial communication
VIN
Voltage Input
Input voltage to the board
5V
Regulated 5V
Output to supply 5V to the circuit
3V3
Regulated 3.3V
Output to supply 3.3V to the circuit
GND
Ground
Common ground for the circuit
Usage Instructions
Integrating with a Circuit
To use the Adafruit Metro Mini in a circuit:
Connect the board to a power source via the VIN pin (6-12V recommended).
Connect the GND pin to the common ground of your circuit.
Utilize the digital and analog pins as required for your project, ensuring you do not exceed the current ratings.
If using PWM, connect to pins 3, 5, 6, 9, 10, or 11.
For I2C communication, use pins A4 (SDA) and A5 (SCL).
Best Practices
Always disconnect the Metro Mini from the power source before making or altering connections.
Use a current limiting resistor when connecting LEDs to the output pins.
Avoid applying voltages higher than 5V to any I/O pin.
Ensure that the total current through all I/O pins does not exceed the limit.
Troubleshooting and FAQs
Common Issues
Metro Mini not recognized by computer: Ensure the drivers are installed and the USB cable is functioning.
Sketch not uploading: Check the board and port settings in the Arduino IDE, and ensure the correct bootloader is selected.
I/O pin not working: Verify that the pin is not being overdriven beyond its current limit and that it is configured correctly in your sketch.
Solutions and Tips
If the Metro Mini is not recognized, try using a different USB cable or port.
When uploading sketches, ensure no other programs are using the same COM port.
Use external power supplies for components that draw more current than the Metro Mini can provide.
Example Code for Arduino UNO
Here is a simple example of blinking the onboard LED using the Arduino IDE:
// Pin 13 has an LED connected on most Arduino boards.
int led = 13;
// The setup routine runs once when you press reset:
void setup() {
// Initialize the digital pin as an output.
pinMode(led, OUTPUT);
}
// The loop routine runs over and over again forever:
void loop() {
digitalWrite(led, HIGH); // Turn the LED on (HIGH is the voltage level)
delay(1000); // Wait for a second
digitalWrite(led, LOW); // Turn the LED off by making the voltage LOW
delay(1000); // Wait for a second
}
Remember to select "Adafruit Metro Mini" as the board in the Arduino IDE before uploading the code. If the Metro Mini is not listed, you may need to install the Adafruit board definitions via the Boards Manager.
For more advanced usage and additional examples, refer to the Adafruit Metro Mini guide and the Arduino language reference.
Open Project in Cirkit Designer
