Re: Writing to GPIO registers on NetBSD/RaspberryPi

[Marc Balmer <marc%msys.ch@localhost>]

Hi There!


Am 03.04.15 um 18:27 schrieb Jean-Baka Domelevo Entfellner:
> Hi there,
> 
> Following discussions last months on this mailing list about how bad it
> is to use /dev/mem and mapping it with mmap to access the hardware
> memory (and I totally agree on this!), I am trying to rewrite for NetBSD
> a piece of hack written for GNU/Linux distros on the RaspberryPi.
> 
> The goal of the project is to turn the RaspberryPi into an FM
> transmitter
> (http://www.icrobotics.co.uk/wiki/index.php/Turning_the_Raspberry_Pi_Into_an_FM_Transmitter).
> As a beginner on NetBSD platforms, I am happy I could familiarize myself
> with the ioctl calls and the gpio (4) kernel interface. I am now able to
> query the number of active pins on the GPIO, read their current status
> and set them to High or Low values. But the aforementioned hack
> necessitates to be able to write to some GPIO registers controlling the
> GPIO clocks, to modulate clock signals that we can then output to some
> GPIO pins.
> 
> I've gone through the gpio and gpioctl code, and I thank Jared and Marc
> for their work, but I couldn't see how to do that... Any clue?

Right now there is only code pulse modulate GPIO pins (PWM).  Maybe you
can elaborate a bit on what you need and we can think about a solution?

- Marc