Quoting Hal Murray <[email protected]>:
[email protected] 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:
https://github.com/ddrown/pps-gmtimer/blob/master/DD-GPS-00A0.dts
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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