PC7PB3GNDGNDGND

GNDLCD Contrast

1314 MISO / PDO

OC4A ICP3 / CLKOPCINT3

LCD DB6LCD DB4 Button A

Yellow LEDPD5PB0GNDGNDPB7PD45V

3017

114

SS

RTS

XCK1 / CTS

A6 ADC8OC0A / OC1C

LCD DB7LCD DB5

LCD ELCD RS

PCINT0

PCINT7ICP1

TDITMSTCK

1820212212501

ADC7ADC5ADC4ADC1ADC9

RXD1TXD1

A0A2A3A4A11OC4D

OC3A / OC4AINT2INT3

T1

SDA to RPi and IMUSCL to RPi and IMU

5VPF7PF5PF4PF1PD6PC6PD2PD3

5V

GND

Left motor direction

PB3PB1

PB2

1415

16

RESET

MISO / PDO

MOSI / PDI

SCKPCINT3PCINT1

PCINT2

Button A LCD DB4Right motor direction

5VPB7PD4PF5PF4PF1

114202122

RTSADC8ADC5ADC4ADC1

A6A2A3A4

TMSTCK

OC0A / OC1CLCD ELCD RS

PCINT7ICP1

AREFPD7PC6PD0PD1PD3PD2PF6PF7

6532101918

ADC10

SCLSDATXD1RXD1ADC6ADC7

A7

A1A0

INT0INT1INT3INT2

TDOTDI

OC4D

OC0BOC3A / OC4A

T0

SCL to RPi AND IMUSDA to RPi AND IMU

Buzzer PWM

BATLEV

PD5PC7PD6PE6PB4PB5PB6PF0PE2

3013127891023

ADC9AIN0

ADC11ADC12ADC13ADC0

A11

A8A9A10A5

XCK1 / CTSOC4AOC4D

OC1A / OC4BOC1B / OC4B

ICP3 / CLKOT1

Button B LCD DB7LCD DB6

Green LED (TXL)Yellow LED

Right encoder XORLeft encoder XOR

Right motor PWMLeft motor PWM

Right encoder BLeft encoder B

INT6PCINT4PCINT5PCINT6

HWB

CTRLOFFON

PWRBPWRAGATEGND

REGSHDN (5 V regulator shutdown)PG (5 V regulator power good)

STAT (power selection status)

Button BButton C

Green LED (TXL)Red Led (RXL)

LCD

ISP

5 V logic

INT1INT0 OC0B

23

PD1PD0

SDASCL

Ground (0 V)AVR I/O pin names

Power control

Arduino digital pin numbersAVR ADC channels

Arduino analog pin numbersUSART

I2CSPI

Interrupts

JTAG

Other peripheral functionsOn-board hardware

PWM outputs (Arduino analogWrite)

Power distribution

Page 1

Romi 32U4 Control BoardATmega32U4 pinout, peripherals, and board power control

GPIO27GPIO26GPIO25GPIO24GPIO23

GPIO22GPIO21GPIO20GPIO19GPIO18

RPI5VRPI3V3GPIO13GPIO11GPIO10GPIO15GPIO14GPIO17GPIO7GPIO6

PWM1

RXD0TXD0

SPI0_SCLKSPI0_MOSI

SPI0_CE1_N

GPIO12GPIO9GPIO8GPIO3GPIO2GPIO16GPIO5GPIO4

GNDGND

PWM0

SCL1SDA1

SPI0_MISOSPI0_CE0_N

SCL to AVR and IMUSDA to AVR and IMU

SCL to EEPROMSDA to EEPROM

ID_SCID_SD

LA (3.3 V output A)LB (3.3 V output B)

HA (5 V input A)HB (5 V input B)

VCC for level shifter OUT

OE (output enable, inverted)IN

Level shifter 1

Level shifter 2Level shifter 3

3.3 Vlogic

Power distributionPower controlGround (0 V)

Raspberry Pi GPIO pin numbersRaspberry Pi UART

Raspberry Pi2C Raspberry Pi SPI

PWM outputsOn-board hardware

RPI5VRPI3V3

RPISHDN (RPi 5 V supply shutdown)3V3

Page 2

Romi 32U4 Control BoardRaspberry Pi pinout, peripherals, and level shifters

Ground (0 V)VBAT (BAT1+)

VRP (reverse protected)VSW (after switch)5V (VCC access)

VREG (5 V regulator output)RPI5V (RPi 5 V access)

RPI3V3 (RPi 3.3 V output)3V3 (3.3 V regulator output)

Optional power buses

Page 3

Romi 32U4 Control BoardPower distribution