Skip to main content

Arduino Uno Board Description

The below is a description of the Arduino Uno board.

The USB port and the power connector are very obvious. The power connector is of the dual-concentric type and the hole into which a plug is inserted feels and is circular, although the plastic around it is square with slightly rounded corners.

Holding the board with the USB and power connectors on the right edge of the board.

There are two rows of female IDC connectors, both of which are single sockets, in other words they differ from the female connectors on a Beaglebone in that there are not two rows in one connector and from the Pi in that they are female, not a spikey male double-row of pins.

On both rows of IDC female connectors, pin 0 is at the left edge of the board furthest from the power and USB sockets.

Read the following tables from the left edge of the board furthest from the power and USB sockets.

Top row

Pin Function
0 ADC5
1 ADC4
2 ADC3
3 ADC2
4 ADC1
5 ADC0
6 V in
7 GND
8 GND
9 5V
10 3.3V
11 Reset
12 IO Ref
13 No markings

Bottom Row

Pin Function
0 RX Input
1 TX Output
2 I/O 2
3 PWM
4 I/O 4
5 PWM
6 PWM
7 I/O 7
8 I/O 8
9 PWM
10 PWM
11 PWM
12 I/O 12
13 I/O 13
14 GND
15 aref (ADC reference?)
16 No markings
17 No markings

Additional notes/questions

  • IO ref is presumably I/O reference value
  • 3.3v Max current 50 milliamps
  • ADC from 0 to 5v
  • ADC is ten bit (0 to 1023)

Connecting serial to serial between Raspberry Pi and Arduino

  • TX Arduino to RX Pi via 4k7 resistor
  • TX Pi to RX Arduino via 1k resistor

It is very important to remember that the GPIO pins of the Raspberry Pi are at a logic level of 3.3 volts and those of the Arduino are 5 volts. Damage can and will occur if they are connected directly together with no level conversion.