State of the test farm

Dan Drown dan-ntp at
Tue Jun 7 05:05:40 UTC 2016

Quoting Hal Murray <hmurray at>:
> bellyacres at said:
>> By configuration I really meant, one could write a fairly simple overlay
>> file that would load on boot.  Basically automagically with the eeprom  on
>> the cape to identify it.  The UART overlay files are all shipped  standard
>> now, one still needs to write one for the gpio-pps.  Not all  that hard, the
>> cape just makes it easier...
> I don't know anything about BeagleBone configuration.  I gather that capes
> can have a small ROM with board ID info.  How does that turn into pin
> configuration?
> What is the default pin configuration?  I'd expect all the leftovers would be
> GPIO and there would be some way to set the direction from userland.

The eeprom on a BeagleBone cape has the name of the device tree  
overlay file to load.  The device tree overlay file handles  
configuring the GPIO and connecting the GPIO to some sort of driver.

For example, the DD-GPS device tree overlay:

This expects pin P8.7 to receive the PPS, pin P9.11 to be TX and P9.13  
to be RX.  It connects the two P9 pins to uart4 (/dev/ttyO4) and the  
P8.7 pin to timer4's hardware timestamp capture feature.

The DD-GPS overlay should be on all recent BeagleBone installs.

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