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Products Manual
USB-2COM-BB - BeagleBone Black Expansion I/O Cape

Introduction of USB-2COM-BB

The USB-2COM-BB is a plug-in RS-232 cape designed for the developers and users of BeagleBone and BeagleBone Black. The USB-2COM-BB BeagleBone RS-232 cape provides two high-speed RS-232 serial interfaces, two high-efficient USB 2.0 ports and one Micro SD card reader. The two RS-232 ports are located to the side of the cape with two 90-degree 10-pin connectors. Two IDC flat ribbon cables with D-Sub 9-pin male serial connectors are provided with the cape to connect the two 10-pin serial connectors. The flat ribbon cable provides the convenience for extended connection of serial devices. This dual RS-232 cape is designed to allow any other capes to be stacked above it without interference mechanically. When there is a need to add four serial ports, user can just stack two USB-2COM-BB modules over BeagleBone and BeagleBone Black.

When the USB-2COM-BB plugged to the USB port of BeagleBone or BeagleBone Black, the two serial ports, two USB ports and the Micro SD card reader are automatically detected and installed. The USB-2COM-BB board is designed with GL852G USB2.0 MTT Hub controller to expand the single USB port on BeagleBone Black and BeagleBone to two USB 2.0 ports for USB connection.

The USB-2COM-BB cape is a high-speed dual RS-232 ports/ dual USB ports /Micro SD reader cape that provides to BeagleBone Black and BeagleBone’s developers a cost-economical expansion I/O module to add two serial ports, two USB ports and one MicroSD card reader for their development.


  • Fully compatible with BeagleBone Black or BeagleBone platform

  • Adds two high speed RS-232 serial ports via USB connection

  • Each serial port provided 384 bytes receive buffer and 128 bytes transmit buffer for high speed data throughput

  • Each serial port communication data rates up to 1 Mbps.

  • Connector: two DB9 Male connectors via IDC flat ribbon cable

  • RS-232 data signals: DCD, RxD, TxD, DTR, GND, DSR, RTS, CTS, RI

  • Two downstream USB 2.0 ports with over-current detection and protection

  • Each downstream USB port supports 5V 500 mA power for external high power USB devices

  • Individual port power management

  • Supports USB 1.1 and USB 2.0 transfer speeds from 1.5 Mbps to 480 Mbps, automatic link and speed detection

  • Plug-and-Play; no software or drivers required

  • Supports SD specification v1.0 / v1.1 / v2.0 / SDHC, up to 32GB

  • Compatible with SDXC, Up to 2TB

  • Micro SD card reader with 480 Mbps USB 2.0 transfer speed

  • CE, FCC approval


USB 2.0 Port
Upstream 2
Downstream 1
Power Mode Self Power Mode
Output Voltage (per port) +5V DC
Output Current (per port) 500 mA (max)
Micro SD Card Reader
Speed 480 Mbps USB 2.0 transfer speed
Support Memory Card Micro SD/ SDHC/ SDXC
Serial Port
Serial Ports Two RS-232 ports
RS-232 Signals DCD, RxD, TxD, DTR, GND, DSR, RTS, CTS , RI
Maximum Bit rates 921,600 bps
Serial Configuration Data bits : 7,8
Parity : None, Odd, Even, Mark , Space
Stop bits : 1, 2
UART FIFO Buffer Size Each port with 128 Bytes FIFO for transmit and 384 bytes FIFO for receive.
Housing Board only
Dimensions 80 mm X 55 mm X 20 mm (L x W x H)
Weight 52 g
Operating Temperature 0°C ~ 70°C (32°F to 158°F)
Humidity 0 to 90% RH. Noncondensing
Storage Temperature -40°C ~ 85°C (-40°F to 185°F)
Safety Approvals CE, FCC

USB port (CN1, CN2) pin-out
  Pin Number Name Description  
  Pin1 VBUS Provides +5 VDC 500 mA (max) output power  
  Pin2 D- USB data-  
  Pin3 D+ USB data+  
  Pin4 GND Ground  
Serial port (DB9 Male connector) pin-out
  Pin Number Name Description  
  Pin1 DCD Input : Data Carrier Detect  
  Pin2 RxD Input : Receive Data  
  Pin3 TxD Output : Transmit Data  
  Pin4 DTR Output : Data Terminal Ready  
  Pin5 GND Ground : Signal Ground  
  Pin6 DSR Input : Data Set Ready  
  Pin7 RTS Output : Request To Send  
  Pin8 CTS Input : Clear To Send  
  Pin9 RI Input : Ring Indicator  


The hardware installation of USB-2COM-BB expansion I/O cape is easy to carry out. Follow the detailed steps given below to install the USB-2COM-BB expansion I/O cape in BeagleBone Black or BeagleBone platform.

Step 1: Turn your BeagleBone Black or BeagleBone platform’s power off, and also shut off the power to any peripheral devices.

Step 2: Fasten four copper tubes, with four nuts, on the BeagleBone Black or BeagleBone platform.

Step 3: Insert the USB-2COM-BB expansion I/O cape into the BeagleBone Black or BeagleBone platform’s interface slot.

Step 4: Fasten the holding screws to fix the USB-2COM-BB expansion I/O module in place.