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rare flickers #467
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Can you remove the comment in |
So I was testing with a recent version of Raspbian Lite and it looks like it indeed induces some brightness fluctuations (see #483), which was less with older versions of Raspbian. Still need to investigate what the reason is. |
First of all many many thanks for your great job hzeller. tail -f /var/log/syslogevery time the cron job sends something on syslog (every 1 minute in my case) the display using the command line loop while [ 1 ]; do logger "test1111111111111111111"; sleep 1; doneI see a very short flicker (when the cron is executed the flicker is more heavy). Disabling the cron systemctl stop cronthe flicker stops definitively :-) . |
Yes it is known that the default kernel in the Raspbian distribution does mess a lot with flicker in the LED display, in particular if it does some IO operations, such as writing to a file or doing something in a terminal logged in remotely (even running It is not clear it this is due to some limited memory bandwidth on the Raspberry Pi hardware, or due to the non-realtime scheduling of the default kernel that comes with the distribution. Unfortunately, the Raspbian distribution does not provide a default realtime kernel to switch to (with the usual PREEMPT_RT, NOHZ, disable RCU tweaks), so this is up to the users at this point to compile that for themselves. Anyway, I suggest to play with compiling an RT kernel (and report back). It might not work however, if this is due to some legitimate hardware limitation such as memory bandwidth of course. |
Check out the new compile-time option in |
Hello,
I got your app running on clean instalation of Raspbian Stretch Lite on RPi3. My matrix consists of 2 parallel chains of 7 32x32 modules (p5). With PWM bits set to 4 I got stable framerate number of 320-360Hz.
Unfortunately there is random amount of flickers after different portions of time. For example everything can be fine for 4 minutes, after this there are 4 flickers in 3-4 seconds interval. In most cases flickers are very fast, lasts for 0,05 second. But sometimes flicker is longer like 0,1-0,3 second and it looks like total black display.
Main loop of my app is very simple:
What can I do to solve this issue?
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