GHI Comms cape - no overlay file in /lib/firmware

We recently purchased the GHI Comms cape, in order to have a nice RS485 port available.
However, even the latest Debian image for the BeagleBone black does not have the required overlay dtbo file!
When the BeagleBone Black boots, I get this:
[ 1.493924] bone_capemgr bone_capemgr: loader: failed to load slot-2 BBORG_COMMS:00A2 (prio 0)

The cause is that the file BBORG_COMMMS-00A2.dtbo is missing.
And sure enough, there is no overlay written for this cape in:

I am guessing that there is an alternative way to get this Cape up and running. I’m moderately OK with linux as a user and admin, but rather new to IoT.

Any help appreciated. This is an important project!

We have brought this up to attention and they are looking into it.

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Gus - thank you very much.
I also called yesterday, and talked to an engineer named Joel. He said he’s looking into it also!
I appreciate the fast response.
I’m eager to get your Comms cape running!
I realize that this is not the biggest ticket item in your inventory, but it’s a product that we intend to use more of (along with other capes).


Is the RS485 connected to UART4? If so then you could read and write to that device as /dev/ttyS* (where * is some number)

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John: it is indeed hooked up to UART4.
I’m sure it’s easy, but how does one enable UART4 for serial? When I try to use it with the ADAFruit library, it’s not there…

Thanks in advance. I’m rather a newbie to IoT, although am I fairly good with Linux and command line stuff.

To read and write the UART4, you treat it as a standard file stream. Open file , read and write as you would in any other file.

Thanks. I have that part down. I was unable to configure the pins. I switched back to the original Angstrom version of Linux that comes with the BB Black, and I can now configure the pins. However, the ADAFruit library still can’t configure UART4… One step at a time!

Oops – I was using the P8 rail rather than P9.

I now have communication going via straight serial between UART1 & UART4. But not through the Cape to an attached USB-to-RS485 converter.

I would think that the Comms cape directly uses the same pins as the standard UART4 pins…

More on this here

As I mentioned on the BB forum, I was able to get the serial communication working.
However, I had to reverse the lines between the two RS485 devices.
I had to hook A to B and B to A.
RS485 devices should just need to be daisy-chained, with all the A’s on one line, and all the B’s on the other.
I suspect a mislabelling on the Comms cape.
But at least it is working!

This labelling issue might confuse others in the future.

We will investigate

We checked and the pins are labeled correctly. Check your wires and the other side please. Share a picture maybe.