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Newsgroups: comp.lang.ada
Date: Tue, 28 Jan 2020 12:18:01 -0800 (PST)
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Subject: Re: GNATCOLL-Mmap example
From: Philip Munts <philip.munts@gmail.com>
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Xref: reader01.eternal-september.org comp.lang.ada:57979
Date: 2020-01-28T12:18:01-08:00
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On Tuesday, January 28, 2020 at 11:11:12 AM UTC-8, Philip Munts wrote:
> Or better yet, use my libsimpleio:
> 
> https://github.com/pmunts/libsimpleio
> 
> The sysfs API for GPIO is now deprecated.
> 

Here is a quick example using libsimpleio:

WITH GPIO.libsimpleio;
WITH RaspberryPi;

PROCEDURE test_gpio IS

  outp : CONSTANT GPIO.Pin :=
    GPIO.libsimpleio.Create(RaspberryPi.GPIO18, GPIO.Output);

BEGIN
  LOOP
    outp.Put(True);
    outp.Put(False);
  END LOOP;
END test_gpio;

On a Raspberry Pi 4, which is what happens to be plugged in today, I measured a 360 kHz square wave at GPIO 18.  Never mess around with memory mapped I/O unless you need insanely high performance.  Then you would probably want to use DMA anyway.

Phil