foto Petr Bravenec

Petr Bravenec
Twitter: @BravenecPetr
+420 777 566 384

The board 4x232 and Beaglebone can be used everywhere you need to collect data from one or more (up to four) buses RS232 or RS485 (external convertor is needed).


  • Boards expands the Beaglebone black microcomputer.
  • 4 × RS232, two ports with hadware flow control (RTS/CTS), two ports with only RXD/TXD lines
  • Real time clock - the clock runs even if the device is switched off.
  • Protected with transil and fuse.
  • Contains the EEPROM with imformation about the board. Can be switched to any of four possible addresses.

Board driver instalation

Debian package can be installed to the Beaglebone's operatig system (Debian Linux, armhf architecture) for simple use of the 4x232 board. The package contains:

  • systemd script for RTC
  • firmware for 4x232 board (file dtbo)
  • udev rules to create special devices /dev/ttyA to /dev/ttD

For easy installation and upgrades add a line to the /etc/apt/sources.list file:

deb [arch=armhf] http://debian.hobrasoft.cz hobrasoft non-free

Then install the package:

apt-get update
apt-get install hobrasoft-4x232

Serial ports

Serial port are labeled with a letter on the board. Special files in /dev directory have names from /dev/ttyA to /dev/ttyD. You can use these names or you can use names usual in BeagleBone (/dev/ttyO1):

/dev/ttyO5/dev/ttyCRS232-CRXD/TXD, RTS/CTS
/dev/ttyO4/dev/ttyDRS232-DRXD/TXD, RTS/CTS


Board 4x232 cannot be used with internal graphics card at the same time. If you want to use the 4x232 board then the internal graphics card must be deactivated and the needed pin of CPU must be released. When the debian package is installed, the graphics card should be deactivated automatically. If you connect your 4x232 board and the board could not be found, please check the /boot/uboot/uEnv.txt file. There must be the line in that file:


If you want to use your internal graphics card again, comment the line out.

EEPROM address

Beaglebone can be expanded with four different boards. Every board must have unique address. The address of the 4x232 board can be set with EEADDR switch:

Address A0 A1
57 Default
56 -
55 -
54 - -

The EEPROM is write protected. If you want to overwrite the memory, connect pins 1 and 2 on the EEWP switch. Please, note, that there is no reason to overwrite the memory since the required content is already written in the memory.


Custom board are not detected automatically. If you want to have the board available automatically, add the board identification to /etc/default/capemgr file:

# Options to pass to capemgr

Then reboot your Beaglebone and try if the board was found:

# dmesg | grep 4x232
[   27.448969] bone-capemgr bone_capemgr.9: part_number 'HOBRASOFT-4x232', version 'N/A'
[   27.449082] bone-capemgr bone_capemgr.9: slot #7: 'Override Board Name,00A0,Override Manuf,HOBRASOFT-4x232'
[   27.449182] bone-capemgr bone_capemgr.9: slot #7: Requesting part number/version based 'HOBRASOFT-4x232-00A0.dtbo
[   27.449199] bone-capemgr bone_capemgr.9: slot #7: Requesting firmware 'HOBRASOFT-4x232-00A0.dtbo' for board-name 'Override Board Name', version '00A0'
[   27.470582] bone-capemgr bone_capemgr.9: slot #7: dtbo 'HOBRASOFT-4x232-00A0.dtbo' loaded; converting to live tree


hobrasoft-4x232.deb - instalation package for 4x232 board for Debian Linux system
HOBRASOFT-4x232-00A0.dts - firmware source for board 4x232, GPL License
HTTP server pro C++ a Qt - single threaded event driven ebedded http server, LGPL License
Fotobot - data collection server for photovoltaic plats, GPL License
FotobotHW 4x232 - board 4x232, Beaglebone, box and installed Fotobot software


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