We all love the ATmega328, and we use them a lot for our own projects. The processor has plenty of GPIO, Analog inputs, hardware UART SPI and I2C, timers and PWM galore - just enough for most simple projects. When we need to go small, we use a Pro Trinket 3V or 5V, but if you want to have USB-to-Serial built in, we reach for an Adafruit METRO Mini.
METRO Mini is the culmination of years of playing with AVRs: Adafruit wanted to make a tiny, breadboard-friendly development board that is easy to use and is hacker friendly. Metro Mini can be programmed with the Arduino IDE (select 'UNO' in the boards dropdown)
- ATmega328 brains - This popular chip has 32KB of flash (1/2 K is reserved for the bootloader), 2KB of RAM, clocked at 16MHz
- Power the METRO Mini with 6-16V polarity protected on the Vin pin, or plug the micro USB connector to any 5V USB source.
- METRO Mini has 20 GPIO pins, 6 of which are Analog in as well, and 2 of which are reserved for the USB-serial converter. There's also 6 PWMs available on 3 timers (1 x 16-bit, 2 x 8-bit). There's a hardware SPI port, hardware I2C port and hardware UART to USB.
- GPIO Logic level is 5V but by cutting and soldering closed a jumper, you can easily convert it to 3.3V logic
- USB to Serial converter, there's a hardware USB to Serial converter that can be used by any computer to listen/send data to the METRO Mini, and can also be used to launch and update code via the bootloader
- Four indicator LEDs, on the top of the PCB, for easy debugging. One green power LED, two RX/TX LEDs for the UART, and a red LED connected to pin PB5 / digital #13
- Easy reprogramming, comes pre-loaded with the Optiboot bootloader, which is supported by avrdude and only uses 512 bytes.
- Beautiful styling by PaintYourDragon and Bruce Yan, in Adafruit Black with gold plated pads.
This version of the METRO Mini 328 comes as a fully assembled and tested development board but without any headers attached. We do include some through-hole headers that you can solder on if you like to use the Metro Mini on a breadboard, or you can solder wires or header directly to the breakout pads.
- ATmega328 microcontroller with Optiboot (UNO) Bootloader
- USB Programming and debugging via the well-supported genuine FTDI FT231X
- Input voltage (Vin): 6-16V (a 9VDC power supply is recommended)
- 5V logic with 3.3V compatible inputs, can be converted to 3.3V logic operation
- 20 Digital I/O Pins: 6 are also PWM outputs and 6 are also Analog Inputs
- 32KB Flash Memory - 0.5K for bootloader, 31.5KB available after bootloading
- 16MHz Clock Speed
- Adafruit Black PCB with gold plate on pads
- 18mm x 44mm x 4mm (0.7" x 1.7" x 0.2")
- Weight: 3g
- Derivative of "Arduino UNO R3 Reference design"