Re: Writing to GPIO registers on NetBSD/RaspberryPi

[Jean-Baka Domelevo Entfellner <domelevo%gmail.com@localhost>]

Hi Marc, hi all,

On Fri, Apr 3, 2015 at 7:05 PM, Marc Balmer <marc%msys.ch@localhost> wrote:

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?

 

Thanks for your answer. In fact I need to be able to write to the 32-bit register on the BCM2835 at address 0x 7e10 1070 (this is the clock manager for the first clock peripheral), and anslo to the 32-bit register just after that, at 0x 7e10 1074 (the clock divisor for the same clock). I'm also interested in knowing how to deal with the PWM (starting at 0x 7820 C000).

Another question: how to use the DMA for this BCM2835? What is the corresponding kernel interface in NetBSD? In the Broadcom documentation (http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf), I see that the "PWM DMA is mapped to DMA channel 5". What does it mean and how to use that?

Sorry if my questions are a bit naive, thanks in advance for your answers.

Regards,

   JB