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by jannis
Mon Apr 13, 2020 9:00 pm
Forum: Advanced users
Topic: Jitter on pigpio's wave tables
Replies: 11
Views: 779

Re: Jitter on pigpio's wave tables

Some more playing around with the "*_freq*" settings in config.txt reveals (no video proof): Decent results (pretty low jitter and constant across different loads): arm_freq=600 arm_freq_min=600 core_freq=500 core_freq_min=500 gpu_freq=500 gpu_freq_min=500 Jitter fluctuating from very few jitter to ...
by jannis
Mon Apr 13, 2020 4:21 pm
Forum: Advanced users
Topic: Jitter on pigpio's wave tables
Replies: 11
Views: 779

Re: Jitter on pigpio's wave tables

Setup Start from Raspbian 2020-02-13 Boot, let SD card expand, reboot Configure WiFi, Wait for Auto-Update to finish Run raspi-config : Boot to CLI instead of Desktop Enable SSH Changes in /boot/config.txt : Disable audio by commenting out #dtparam=audio=on Disable the camera by adding start_x=0 Up...
by jannis
Mon Apr 13, 2020 3:56 pm
Forum: Advanced users
Topic: Jitter on pigpio's wave tables
Replies: 11
Views: 779

Re: Jitter on pigpio's wave tables

Ooookay, results time :) I've made some video of my oscilloscope (the screenshots were not as meaningful as the videos and I wrote down what I did and what I saw. I used markdown and that's why I'm hosting it on my cloud for now. I might copy the very long text into here later (need a solution for t...
by jannis
Sun Apr 12, 2020 3:55 pm
Forum: Advanced users
Topic: Jitter on pigpio's wave tables
Replies: 11
Views: 779

Re: Jitter on pigpio's wave tables

HermanSW, thanks for the hints. I've made a quick test with pigpiod running with "-s 1" and it didn't really make a noticable difference for my use case. The dimmer connected to the DMX512-signal that the Pi generates still flicker occasionally. Running the system with temp_limit set to 5 in config....
by jannis
Fri Apr 10, 2020 7:59 pm
Forum: Advanced users
Topic: Jitter on pigpio's wave tables
Replies: 11
Views: 779

Re: Jitter on pigpio's wave tables

Do you think it's possible to get (extremely low but) constant clocks by setting temp_limit in config.txt to a very low (=20°C) value?
I'll give it a try ;)
by jannis
Thu Mar 26, 2020 9:23 pm
Forum: Advanced users
Topic: Jitter on pigpio's wave tables
Replies: 11
Views: 779

Re: Jitter on pigpio's wave tables

The final plan is to NOT run headless, but for now it wouldn't be a problem. I observed that on the Pi 1 and 3, having a screen attached at boot time makes a huge difference, on the 4 not so much. I am running headless in the sense that no X server or wayland compositor is running, yes. Would I be a...
by jannis
Thu Mar 26, 2020 8:00 pm
Forum: Advanced users
Topic: Jitter on pigpio's wave tables
Replies: 11
Views: 779

Re: Jitter on pigpio's wave tables

Oh, what I forgot since I also suspect clocks chaning their speeds: What is the best set of configuration options to make sure that all hardware parts (CPU, GPU, everything else) always runs at the same speed? Currently I have in config.txt: disable_overscan=1 dtparam=i2c_arm=on dtoverlay=i2c-rtc,ds...
by jannis
Thu Mar 26, 2020 7:38 pm
Forum: Advanced users
Topic: Jitter on pigpio's wave tables
Replies: 11
Views: 779

Jitter on pigpio's wave tables

Hi, I'm trying to generate DMX512 output via the Raspberry Pi's (currently a Raspberry Pi 4 Model B Rev 1.1 but I do have others) GPIOs using pigpiod and it's wave table functions (docs beginning at http://abyz.me.uk/rpi/pigpio/pdif2.html#wave_clear). The code that generates the wave table is here: ...
by jannis
Sat May 09, 2015 2:35 pm
Forum: Other projects
Topic: Rassberry Pi and Jack audio
Replies: 70
Views: 63309

Re: Rassberry Pi and Jack audio

Hi Keith, are you using a wireless or wired connection? If wifi, can you try a wired connection first? Jack transfers raw audio which means it is pretty heavy on the bandwidth, especially on the Pi. Maybe you can use jack2 (versions 1.9.X)? The network audio works completely different there and shou...
by jannis
Wed Nov 07, 2012 10:02 am
Forum: Other projects
Topic: Rassberry Pi and Jack audio
Replies: 70
Views: 63309

Re: Rassberry Pi and Jack audio

Ah right, forgot about the USB-"sound card" thing. O Assuming you want to have sound input via your "USB sound card" and sound output via the RPi's analog audio jack: Configure jack to use your USB sound card as primary backend (via ALSA). Then use alsa_out as I posted earlier to get the sound to th...
by jannis
Wed Nov 07, 2012 9:12 am
Forum: Other projects
Topic: Rassberry Pi and Jack audio
Replies: 70
Views: 63309

Re: Rassberry Pi and Jack audio

If you mean the error with "mmap" in the output: This is due to the RPi's ALSA-driver and can be worked around using the method I described earlier.
by jannis
Tue Nov 06, 2012 10:21 pm
Forum: Other projects
Topic: Rassberry Pi and Jack audio
Replies: 70
Views: 63309

Re: Rassberry Pi and Jack audio

billb wrote:So I thought I was well on my way to having a neat little guitar effects processor, but then I started seeing jack crashing / failing to start, then started Googling, then found this topic. :(
What messages/errors do you see from jack? Which settings do you use?
by jannis
Sat Oct 27, 2012 11:59 am
Forum: Other projects
Topic: Rassberry Pi and Jack audio
Replies: 70
Views: 63309

Re: Rassberry Pi and Jack audio

I tried Gentoo and finally got jack2 installed version 1.9.9.4 from the pro-audio overlay. but I am still getting the same bus error. I also tried to install the 1.9.8 version but the sources are missing. You mean version 1.9999? That'd be jack1 then (a live ebuild). pro-audio overlay is perfectly ...
by jannis
Thu Oct 18, 2012 5:47 pm
Forum: General discussion
Topic: JACK, midi and synths.
Replies: 7
Views: 4740

Re: JACK, midi and synths.

I got JACK working on the RPi and posted my solution to: http://www.raspberrypi.org/phpBB3/viewtopic.php?f=41&t=5787&p=196500#p196500 About VST: forget it :) LADSPA and LV2: depends on the plugins but most of them are quite CPU-intensive (doing spectral analysis via FFT, heavy floating-point calcul...
by jannis
Wed Oct 17, 2012 9:10 pm
Forum: Other projects
Topic: Rassberry Pi and Jack audio
Replies: 70
Views: 63309

Re: Rassberry Pi and Jack audio

I had that "cannot allocate memory" error when not using "-p 8" that's why I'm using it at all. But on my RPi, it doesn't try to lock that much memory ... Can you try with 4 ports? Wait, it tries to allocate about 13MB of RAM and fails? That is strange. The only difference might be that I'm running ...
by jannis
Wed Oct 17, 2012 7:31 pm
Forum: General discussion
Topic: JACK, midi and synths.
Replies: 7
Views: 4740

Re: JACK, midi and synths.

I got JACK working on the RPi and posted my solution to: http://www.raspberrypi.org/phpBB3/viewtopic.php?f=41&t=5787&p=196500#p196500 About VST: forget it :) LADSPA and LV2: depends on the plugins but most of them are quite CPU-intensive (doing spectral analysis via FFT, heavy floating-point calcula...
by jannis
Wed Oct 17, 2012 7:28 pm
Forum: Other projects
Topic: Rassberry Pi and Jack audio
Replies: 70
Views: 63309

Re: Rassberry Pi and Jack audio

Argh, I feel a little dumb right now since it took me so long to get this idea. I got jack-audio-connection-kit running on the RPi! Here's how you do it: - Install jack from "jack2"-branch (was jack-dmp) (for example jack-1.9.8) - Run jack using the "dummy"-driver without realtime: "jackd -r -p 8 -d...
by jannis
Tue Oct 16, 2012 6:19 pm
Forum: Gentoo
Topic: Gentoo Linux
Replies: 114
Views: 60941

Re: Gentoo Linux

Ah, the wrapper-script! Sorry it took so long. I had in my mind that the wrapper is on the machines doing the actual compilation (my desktop or laptop) but in reality the wrapper-script is on the RPi. And I didn't have it at home since I gave it to a friend. Now it's back and here's the wrapper-magi...
by jannis
Tue Oct 09, 2012 7:03 am
Forum: Gentoo
Topic: Gentoo Linux
Replies: 114
Views: 60941

Re: Gentoo Linux

That way of cross-compiling won't work. You can't chroot into an ARM-system an a x86/x86_64 system because you cannot execute ARM-binaries on that host. The way to go is to setup a cross-compiler on your x86/x86_64 system (easy with crossdev) and then use distcc for cross-compiling: http://www.gent...
by jannis
Wed Sep 05, 2012 6:15 am
Forum: General discussion
Topic: Simon's accelerated X development thread
Replies: 405
Views: 153315

Re: Simon's accelerated X development thread

Here's another guide about distcc and cross-compiling:
http://www.gentoo.org/doc/en/distcc.xml

and since we're at it:
http://www.phoronix.com/scan.php?page=n ... px=MTE3NTE
anyone here in the forums knows more about that?
by jannis
Sat Aug 11, 2012 11:58 am
Forum: Other projects
Topic: Rassberry Pi and Jack audio
Replies: 70
Views: 63309

Re: Rassberry Pi and Jack audio

I may repeat myself here, but it's not jack's fault: jackd won't run on the Pi with the current driver since jackd tries to mmap the audio and exactly that operation is not supported by the alsa-driver for the BCM-sound part When trying to "lock" memory using: http://pyropus.ca/software/memtester th...
by jannis
Fri Jul 27, 2012 8:33 pm
Forum: Other projects
Topic: CAN Interface
Replies: 103
Views: 112660

Re: CAN Interface

In that regards, while the MCP2515 is a great CAN chip, why not go with a more "open hardware" friendly STN1110, which is still lightning fast with CAN but also compliant with other protocols? Additionally, it supports the "AT" command set (basically the same as used with modems) so I'm sure progra...
by jannis
Thu Jul 26, 2012 2:36 pm
Forum: Gentoo
Topic: Gentoo Linux
Replies: 114
Views: 60941

Re: Gentoo Linux

There are no patches, there's "only" the github-repository: https://github.com/raspberrypi/linux and a fork that uses a slightly newer kernel: https://github.com/bootc/linux/tree/rpi-3.2.23 I once tried to get the patches out from the repo and apply them to 3.3 and failed. Is there any reason why yo...
by jannis
Thu Jul 26, 2012 6:02 am
Forum: Gentoo
Topic: Gentoo Linux
Replies: 114
Views: 60941

Re: Gentoo Linux

Don't use gentoo-sources, it misses needed patches. http://lmgtfy.com/?q=raspberry+pi+kernel

Setting up a cross-compiler for gentoo:
http://lmgtfy.com/?q=gentoo+cross+compiler

Using distcc with it:
http://lmgtfy.com/?q=gentoo+distcc+cros ... ling+guide
by jannis
Thu Jul 19, 2012 12:40 pm
Forum: Other projects
Topic: CAN Interface
Replies: 103
Views: 112660

Re: CAN Interface

Thanks for the input. I was reading some summaries about socketcan. I think it is a good basis for the project. I've not much knowledge about this piece of software yet, but i think the timestamps are not integrated because of the (quite expensive) PAEK Systems hardware. I think they are added thro...

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