On Thu, Jan 16, 2020 at 11:39 AM TJF <[email protected]> wrote:

> There's no supervisor mode for the PRU.
>
> There's no tri-state-mode for AM335x GPIO.
>
> In order to change direction for a pin on a GPIO-SS, it needs a write
> access to its OE register. The PRU can do that.
>
> Find an example at
> https://github.com/DTJF/libpruw1/blob/master/src/bas/w1_prucode.p, which
> is a driver for a one-wire (w1) bus, reading and sending data on a single
> GPIO line for multiple divices. The library documentation is at
> http://users.freebasic-portal.de/tjf/Projekte/libpruw1/doc/html/
>

Thanks for the great example!

For those that don't quite follow, you are using the chip-level or
SoC-level GPIO subsystem for this example and not the PRU subsystem GPIOs
that can be accessed directly from R30/R31 on the PRU CPU itself. For those
pins, the PADCONF or pinmux settings must be adjusted at the chip/SoC-level
to disable the PRU GPIO output.


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