BB White: RS485 Caper not initializing

Hi everyone, it’s my very first post here.

I’m working on a Beagle Bone White to make it communicate via RS485, using a newly purchased RS485 cape.
After facing some ioctl errors 22: invalid argument with my software i tried to check what dmseg says and found that:

Linux version 3.2.34 (koen@Angstrom-F16-vm-rpm) (gcc version 4.5.4 20120305 (prerelease) (GCC) ) #1 Wed Nov 21 14:17:11 CET 2012

dmesg | grep cape
[ 0.100158] cape: pcm register
[ 0.250427] BeagleBone cape EEPROM: found eeprom at address 0x54
[ 0.250427] BeagleBone cape: Beagleboardtoys. BeagleBone RS485 CAPE…, revision 00A1
[ 0.250457] BeagleBone cape partnumber: BB-BONE-SERL-04.
[ 0.250457] BeagleBone cape: not initializing RS485 cape <--------------------------------------------------------------------------
[ 0.302185] BeagleBone cape EEPROM: could not read eeprom at address 0x55
[ 0.362243] BeagleBone cape EEPROM: could not read eeprom at address 0x56
[ 0.422271] BeagleBone cape EEPROM: could not read eeprom at address 0x57
[ 0.422271] BeagleBone cape: initializing mmc
[ 0.422576] BeagleBone cape: exporting ADC pins to sysfs
[ 0.422943] BeagleBone cape: exporting SPI pins as spidev
[ 0.423248] BeagleBone cape: initializing w1-gpio

Have you got any suggestion why the cape is not being initialized? Where am I failing?

I checked with another beagle bone of a friend obtaining the same fail, while a RS232 cape works with no problem.

I deeply thank you in advance. :slight_smile:


  • There’s currently no software support for BeagleBone RS485 Cape. This cape is sold for development purposes only.

I read something about it being made for a non-linux OS initially, my guess is VxWorks. If you want to get it working, you’ll need to enable the UART4 and manipulate the two GPIO pins for the transceiver.