Expansion Hub Specifications

The REV Robotics Expansion Hub (REV-31-1153) is a low-cost educational device that can communicate with any computer (commonly the REV Robotics Control Hub or an Android Phone) to provide the interfaces required for building robots and other mechatronics. The Expansion Hub was purpose built to stand up to the rigors of the classroom and competition field. It features a mature firmware designed for basic and advanced use cases with the ability to be field upgraded in the future.

The IO ports of the Expansion Hub are identical in specification to the Control Hub. Within this documentation, many sections may refer to the Control Hub, but the connections are the same for the Expansion Hub.

The REV Robotics Expansion Hub is an approved device for use in the FIRST Tech Challenge and FIRST Global.

Port Label	Qty	Connector	Description
Battery	2	XT30	Connect one 12V NiMh battery, add an Expansion Hub with second port
Motor	4	JST VH, 2-pin	Motor power output
Encoder	4	JST PH, 4-pin	Quadrature encoder input
Servo	6	0.1” Header	Extended range 5V servo output (500-2500ms)
5V Aux Power	2	0.1” Header	Auxiliary device 5V/2A
Analog	4	JST PH, 4-pin	Analog input 0-5.0V measurement range with two channels per connector. 3.3V provided on the connector power pin.
Digital	8	JST PH, 4-pin	Digital Input/Output with two channels per connector
I2C	4	JST PH, 4-pin	Four separate I2C busses, 100kHz/400kHz bus speed
RS485	2	JST PH, 3-pin	Serial communication port to add a Hub (Control or Expansion)
UART	2	JST PH, 3-pin	Debugging only
MINI USB	1	USB Mini-B	Connect directly to the Robot Controller Android device or PC

Specifications

The following tables provide the operating and mechanical specifications for the Expansion Hub.

DO NOT exceed the absolute maximum electrical specifications. Doing so will cause permanent damage to the Expansion Hub and will void the warranty.

Input Power Specifications

Parameter	Min	Typ	Max	Units
Operating voltage range ($V_{IN}$)	8	12	15	V
Absolute maximum supply voltage	-	-	15	V

Motor Port Specifications

Parameter	Min	Typ	Max	Units
Continuous output current †	-	-	10	A
Absolute maximum output current ‡	-	-	20	A

†	Exceeding the continuous current maximum depends on many thermal factors. The outputs will self protect once they approach their thermal limit.
‡	Maximum current is ultimately limited by the in-line battery fuse.

Encoder Port Specifications

Parameter	Min	Typ	Max	Units
Encoder port input voltage	0	-	3.3	V
Encoder port supply voltage	-	-	3.3	V
Encoder port total supply current	-	-	500	mA

See Sensors - Encoders for more information on encoders and using the encoder ports. For using non-REV motor encoders see Using 3rd Party Sensors - Encoders for more details.

Digital Port Specifications

Parameter	Min	Typ	Max	Units
Digital port input voltage	0	-	3.3	V
Digital port supply voltage	-	-	3.3	V
Digital port total supply current	-	-	1	A

See Sensors - Digital for more information on using the digital ports. See Using 5V Sensors for information on using 5V logic level devices with the digital ports.

Analog Port Specifications

Parameter	Min	Typ	Max	Units
Analog port input voltage range †	0	-	5	V
Analog port supply voltage	-	-	3.3	V
Analog port total supply current	-	-	500	mA

†	The analog input will accept up to 5V. When using 5V analog sensors, a custom wiring harness is needed to provide 5V of power for the sensor as the power pin provides 3.3V.

See Sensors - Analog for more information on using the analog ports.

I2C Port Specifications

Parameter	Min	Typ	Max	Units
I2C port input voltage range	0	-	3.3	V
I2C port supply voltage	-	-	3.3	V
I2C port total supply current	-	-	500	mA
Bus speed	-	100/400	-	kHz
I2C pull-up resistor	-	2.49	-	kΩ

Expansion Hubs purchased AFTER December 2021 no longer include an internal IMU

See Sensors - I2C for more information on using the I2C ports. See Using 5V Sensors for information on using 5V logic level devices with the I2C ports.

Servo Port Specifications

Parameter	Min	Typ	Max	Units
Servo output signal voltage	0	-	5	V
Servo port supply voltage	-	5	-	V
Servo port pair total supply current †	-	-	2	A
Absolute maximum total supply current ‡	-	-	5	A
Servo port output pulse range	500	-	2500	μs

†	Total supply is shared across pairs of ports (0-1, 2-3, 4-5)
‡	The 5A total supply current for all servo ports and +5V power ports is shared.

+5V Power Port Specifications

Parameter	Min	Typ	Max	Units
+5V power port output voltage	-	5	-	V
+5V power port pair total supply current †	-	-	2	A
Absolute maximum total supply current ‡	-	-	5	A

†	Total supply current is shared across both ports
‡	The 5A total supply current for all servo ports and +5V power ports is shared.

Mechanical Specifications

Parameter	Min	Typ	Max	Units
Body length	-	103	-	mm
Body width	-	143	-	mm
Body height	-	29.5	-	mm
Weight	-	209	-	g
Mounting hole pitch	-	16	-	mm