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by Elmi
Mon May 21, 2018 5:34 pm
Forum: Bare metal, Assembly language
Topic: Timer interrupt example
Replies: 8
Views: 5681

Re: Timer interrupt example

Yes, this was what I was looking for - thanks!
by Elmi
Mon May 21, 2018 3:30 pm
Forum: Bare metal, Assembly language
Topic: Timer interrupt example
Replies: 8
Views: 5681

Re: Timer interrupt example

OK, there seems to be a misunderstanding: I don't have any operating sytem running, I want to do real bare-metal programming with direct hardware accesses. Means: - write address of my timer ISR into related register - write timer divider/compare values into related registers - enable timer interrup...
by Elmi
Mon May 21, 2018 2:40 pm
Forum: Bare metal, Assembly language
Topic: Timer interrupt example
Replies: 8
Views: 5681

Re: Timer interrupt example

Hm, what is the difference between both? Finally I would like to have an interrupt-frequency of at least 2 Mhz, so whatever timer fits better for this...
by Elmi
Mon May 21, 2018 8:24 am
Forum: Bare metal, Assembly language
Topic: Timer interrupt example
Replies: 8
Views: 5681

Re: Timer interrupt example

I'm totally aware of the fact that I can't see a LED blinking when it is triggered by a timer. But this is not a problem, I also can check the frequency at an GPO using an oscilloscope. But: I definitely have to do it with a timer interrupt, the code that has to be executed may be different on every...
by Elmi
Sun May 20, 2018 5:36 pm
Forum: Bare metal, Assembly language
Topic: Timer interrupt example
Replies: 8
Views: 5681

Timer interrupt example

This question is completely independent from my previous one and is really about plain bare metal programming: I want to use a timer of the fourth CPU-core (Pi 3B) to call an interrupt service routine regularly. The LED-blinking-examples I find in miscellaneous examples mainly use an endles loop wit...
by Elmi
Sun May 20, 2018 1:57 pm
Forum: Advanced users
Topic: Realtime operations with plain Linux kernel
Replies: 0
Views: 196

Realtime operations with plain Linux kernel

Hi, I want to do some time-critical bitbanging with the Pi3 and a plain Linux system. Using the High-Res Timer of the kernel is not enough, it does not seem to go below of about 500 kHz interrupt frequency while the hardware timers of the SoC are capable of doing much more. So my idea is as follows:...
by Elmi
Sun May 20, 2018 1:47 pm
Forum: Bare metal, Assembly language
Topic: Fast timer interrupt?
Replies: 2
Views: 745

Re: Fast timer interrupt?

Great - thanks!
by Elmi
Sun May 20, 2018 9:08 am
Forum: Bare metal, Assembly language
Topic: Fast timer interrupt?
Replies: 2
Views: 745

Fast timer interrupt?

Hi, I know this is not a bare-metal question, but for me it seems this board fits best - feel free to move this thread when there is a better location. I want to set-up a timer-interrupt which calls an IRQ with a frequency of at least 2 MHz to do some stuff regularly. The timers of the SoC seem to b...
by Elmi
Fri May 18, 2018 8:37 am
Forum: General discussion
Topic: Open Source hardware?
Replies: 13
Views: 1106

Re: Open Source hardware?

by Elmi
Fri May 18, 2018 8:04 am
Forum: General discussion
Topic: Open Source hardware?
Replies: 13
Views: 1106

Open Source hardware?

Hi,

the description page about the compute module states that there is an "open-source breakout board" available - but only with the link to the hardware itself. So my question: where are the production/hardware data of this breakout-board available?

Thanks!
by Elmi
Tue Dec 08, 2015 10:00 am
Forum: Advanced users
Topic: use RasPi as USB CDC device?
Replies: 7
Views: 1139

Re: RasPi Zero realtime capabilities?

OK, so once again to not to get more pointers to bare metal examples: My problem is NOT how to toggle some GPIOs in bare metal! This is only a small part of the job to be done in my application. The critical point is USB communication and there is no example and no documentation available which woul...
by Elmi
Tue Dec 08, 2015 9:51 am
Forum: Advanced users
Topic: use RasPi as USB CDC device?
Replies: 7
Views: 1139

Re: RasPi Zero realtime capabilities?

Given that you have failed to find the thousands of pages of SoC and CPU documentation and the many web articles about toggling Pi GPIO and failed to notice this is a bare metal forum so excludes an operating system like Linux I'd say it's likely you wouldn't understand anything posted here. Given ...
by Elmi
Tue Dec 08, 2015 6:29 am
Forum: Advanced users
Topic: use RasPi as USB CDC device?
Replies: 7
Views: 1139

use RasPi as USB CDC device?

Hi, since the possibilities for bare metal programming are quite limited due to the poor documentation of the CPU (yes, I know there are a lot of example codes out there but still not enough for what I need), I'm thinking about running a realtime Linux to avoid the troubles with this closed, IP-prot...
by Elmi
Fri Nov 27, 2015 6:26 am
Forum: Bare metal, Assembly language
Topic: Create USB CDC device?
Replies: 1
Views: 994

Create USB CDC device?

The new Raspberry Pi Zero is very interesting for several new applications. However for realtime programming the poor documentation of the CPU still seems to be a problem. So: are there any information available about how to access the USB device on low level? Or any more detailled about how to use ...

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