The Arduino Pro Mini board is the size of a flash drive, but it has 14 full I/O ports, 6 of which are analog PWM ports. The platform is based on the ATmega168 8Mhz or 16Mhz microcontroller (ATmega328). Let’s take a closer look at the Arduino Pro Mini board’s schematic, the pinout of the ports, the characteristics and the programming (firmware) of this model.
Arduino Pro Mini: pinout of the board
The characteristics of the Arduino Pro Mini 5V board do not differ from the Arduino Nano board. The main difference is that there is no USB-UART chip for flashing the Pro Mini board. Communication with the PC is done via FTDI cable or with the optional Sparkfun board. Due to this, the size of the board is more compact, which allows you to use the platform in ready mini-projects, where small dimensions of components are important.
The numbering of the ports and their purpose completely duplicate the Arduino UNO r3 board. Of the 14 input-output ports, 6 ports can operate in PWM mode with a resolution of 8 bits. The serial bus UART is on ports 0 (RX), and 1 (TX), the communication via I2C protocol on Pro Mini Arduino with LCD display is on analog ports with additional functions in operation: port A4 (SDA) and port A5 (SCL).
Arduino Pro Mini Specifications
- Microcontroller: ATmega168 or ATmega328
- Clock frequency: 8 MHz and 16 MHz
- Input supply voltage: 3.3-12V or 5-12V
- Logic level voltage: 3.3 or 5 V
- General-purpose I/O ports: 20
- Maximum current from I/O pins: 40mA
- PWM enabled ports: 6
- ADC Connected Ports: 8
- ADC Width: 10 bit
- Flash memory: 16kb
- SRAM memory: 1kb
- EEPROM-memory: 512 bytes
- Board dimensions: 33×18 mm
Arduino Pro Mini: Board power, ports
Arduino Pro boards come with two power options – 3.3 volts for the 8 MHz microcontroller and 5 volts for the 16 MHz microcontrollers. Both versions are connected to a power supply via an FTDI cable or a Sparkfun board. The stabilized voltage of 3.3V or 5V (depending on the model) can be connected to the VCC port. The unregulated source is connected to the RAW port.
Pro Mini: power from an external source
- 5V: supplies a 5V pin from the internal regulator
- 3.3V: supplies 3.3V on this pin, can be used to connect devices
- GND – pin for the ground connection
- VIN – pin for the connection of an external power source
- IREF – pin for informing about the operating voltage of the board
Arduino Pro Mini: Firmware, programming
The Arduino Pro Mini microprocessor is designed with a built-in loader, i.e., writing sketches to the board without the use of programmers. This makes it much easier to work with the board, especially for beginners. Arduino Pro Mini ATmega328 firmware is made in Arduino IDE 1.8, which can be downloaded from the developer’s website www.arduino.cc. No additional drivers are required for the Pro Mini Arduino.
The Pro Mini supports three types of memory:
Flash memory of 16kB, used to store firmware. When you write a program to the controller, it is stored in the Flash memory. To clear the Flash memory, you have to load an empty sketch (program).
The SRAM is the 1kB RAM of the Arduino Pro Mini. This is where the variables created in the sketch are stored. SRAM is a non-volatile memory. When you turn off the external power supply – the data will be deleted.
EEPROM is a 512 bytes non-volatile memory. This is where you can save data that will not be erased when you disconnect the power supply. The disadvantage of this memory is the limitation of overwrite cycles – no more than 100 thousand times.