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

#1

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!
Best,
Todd

#2

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

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#3

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).

Best,
Todd

#4

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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#5

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.

#6

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.

#7

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!

#8

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…

#9

More on this here

https://groups.google.com/d/msg/beagleboard/f3nr7TicKjE/RKPYXkBeAQAJ

https://groups.google.com/d/msg/beagleboard/xNrhc-SWkew/KjyqAUScAQAJ

#10

Thanks!
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.
-Todd

#11

We will investigate

#12

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