RS232 Cape RevA

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BeagleBone RS232 Cape

The BeagleBone RS232 Cape provides an RS232 interface to the BeagleBone via a standard D-Sub 9 female serial connector. This connector is located to the side so it doesn't interfere with any capes stacked above it. By default, the BeagleBone RS232 Cape uses UART2 port on the AM335x for RS232 connection; however, users will have the freedom to choose among UART1, UART2, UART4, and UART5 ports.


Please visit our Frequently Asked Questions (FAQ) page for additional help.

Revision Changes

Revision A1

Initial release of BeagleBone RS232 Cape.

Software Support

  • BeagleBone RS232 Cape revision A1 is supported by Angstrom release 06-18-12 or later.

  • Major BeagleBone image releases can be downloaded here.
  • Intermediate BeagleBone image releases can be downloaded here

Please follow the instructions here to write the image file to your SD card on a Windows machine.

Getting Started

Required setup:

  • A BeagleBone RS232 Cape
  • A BeagleBone (with supporting software)
  • A USB cable
  • An RS232 compatible serial cable (the connector on RS232 Cape is female; therefore, you will need a male D-Sub to USB or D-Sub to D-Sub)
  • A computer

Following the instructions below to start using your BeagleBone RS232 Cape:

  1. Mount the BeagleBone RS232 on top of BeagleBone
  2. Make sure the micro SD card using with BeagleBone has latest Angstrom image.
  3. Connect the BeagleBone RS232 Cape to the computer using a RS232-compatible serial cable. Remember the port number of this connection.
    • Note: In Windows, the serial port number can be viewed under “Ports (COM & LPT)” section inside “Device Manager”. To open the “Device Manager” windows, right-click “My Computer”, choose “Properties”, select the “Hardware” tab, and click “Device Manager”.
  4. Connect the BeagleBone to the computer using a USB cable. Remember the port number of this connection. This will also power up the BeagleBone.
  5. Open a terminal application (Teraterm, Hyperterminal, etc) and open new connection with following settings: baud rate - 115200, data – 8 bit, parity – none, stop – 1 bit, flow control – none. Select the port corresponding to the RS232 connection.
  6. Open a second instance of the terminal application and connect to the USB serial connection using the same settings as above.
  7. Hit the reset switch S1 on the BeagleBone. The BeagleBone is now rebooting inside the USB serial terminal window.
  8. Press “Enter” to stop the booting process at UBoot. If missed, hit the reset switch again and press “Enter” before the UBoot count down stops at zero.
  9. At UBoot, run the following commands to temporarily use the RS232 connection:
    • setenv console ttyO2,115200n8
    • boot
  10. BeagleBone will continue the booting process; however, the kernel messages will now show up inside the RS232 terminal window. You can now start using the RS232 connection via UART2.
    • Note: This RS232 connection is temporary. To permanently use the RS232 connection, you need to change the environment variables of UBoot.


Electrical Specifications

Compatible Serial Ports UART1
UART2 (default)
Power 3.3V via expansion header
Indicator Power LED
Connectors Two 46-position connectors
One 10-position connector
One D-Sub9 serial connector

Mechanical Specifications

Size 3.40" x 2.45"
Layers 4
PCB Thickness .062"
RoHS Compliant Yes

Signal Usage

BeagleBone RS232Pin Usage

The BeagleBone RS232 Cape uses 7 signals including:

  • DGND
  • VDD_3V3EXP
  • I2C_SDA
  • I2C_SCL


EEPROM Suport Yes
Board Name BeagleBone RS232 Cape
Version 00A1
Manufacturer BeagleBoardToys
Part Number BB-BONE-SERL-03
Pins Used 15


Product Images


System Reference Manual

Hardware Files

BeagleBone RS232 Revision A1

To download all files at once please click here