Antwort: ARM linux gpio speed

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Author: H.Haeberle@pilz.de
Date:  
To: geert.jacobs
CC: linux-arm
Subject: Antwort: ARM linux gpio speed
I was posting a fiq test about 2 weeks ago in linux-arm-kernel. I got a
frequency up to about 500kHz with that solution. Should work as a pwm with
1 khz with no problem. I don't have the sourcecode right now, but I can
send it - if you don't find it on the mailinglist - later this week.

Heinz




                                                                                                          
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                                                                   Thema:  ARM linux gpio speed                                   


                       03.01.02 10:21                                                                                             






Hello,

We are making a demo on an Intrinsyc development board that has a
StrongARM SA1110. OS is HardHat Linux. We want to use a GPIO pin as a PWM.
Using this PWM we can make a backlight by switching some LEDs.

We already tried using the kernel timers of linux, but they were too slow
to make a decent PWMfrequency (100Hz max gave a flickering backlight). We
experimented with threads yesterday, but they are apparently also dependent
of the kernel timers.
Using microdelay is also not an option since it occupies the processor, so
nothing else can be done during the waiting time.

What we are looking for is a way to switch a GPIO pin as fast as possible
in the background of an application. We want to implement all this in a
module.

any ideas or suggestions?

Nicolas and Geert
SW engineers

=============================================================
Geert Jacobs
Philips TASS Belgium
Tweestationsstraat 80
1070 Brussel
Tel: +32 2 525 70 74
Fax: +32 2 525 70 69




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