# FM6363C + DP32019B Flickering **URL:** \ **Category:** Uncategorized\ **Created:** [July 22, 2026, 10:33pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/fm6363c-dp32019b-flickering/1239 "2026-07-22T22:33:50Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![raulzanardo](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/raulzanardo/32/869_2.png) [@raulzanardo](https://rpi-rgb-led-matrix.discourse.group/u/raulzanardo)\ **Post date:** [July 22, 2026, 10:33pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/fm6363c-dp32019b-flickering/1239/1 "2026-07-22T22:33:50Z")
Hi to you all! I’m using the [experimental lib](https://github.com/kingdo9/rpi-rgb-led-matrix_pwm_experiment) from [kingdo9](https://github.com/kingdo9), it is working fine but still have some flickering in the brightness, my current specs are this: There are [two 128x64](https://github.com/hzeller/rpi-rgb-led-matrix/issues/1704) in parallel, they have the chips FM6363C and DP32019B and I’m running on a RPI3B+ with a little bit of overclock, the RT Kernel ( I did the [SPWM Tuning Guide](https://github.com/kingdo9/rpi-rgb-led-matrix_pwm_experiment/blob/master/spwm.md) and Real Time Kernel Setup Guide), this test script: ```bash #!/bin/bash export SPWM_END_OF_FRAME_EXTRA_ROW_CYCLES=18 export SPWM_FRAME_END_SLEEP_US=300 taskset -c 2 chrt -f 99 /home/raul/apps/rpi-rgb-led-matrix_pwm_experiment/examples-api-use/demo \ -D15 \ --led-panel-type=fm6363 \ --led-gpio-mapping=regular \ --led-brightness=30 \ --led-rows=64 \ --led-cols=128 \ --led-chain=1 \ --led-parallel=2 \ --led-limit-refresh=60 \ --led-spwm-row-addr-type=0 \ --led-scan-mode=0 \ --led-slowdown-gpio=3 \ --led-no-busy-waiting \ --led-pwm-bits=11 \ --led-spwm-register-config=0 \ --led-pixel-mapper="Rotate:90" \ --led-rgb-sequence=BGR ``` [This is the video](https://imgur.com/a/rpi-rgb-led-matrix-experiment-9Bn7dOd) of the text D15 and D0 and some other matrix for comparison It seams the the bright variations happens across the entire axis in both matrices at the same time. I’ve monitored the power supply with an osciloscope and there was no variation in voltage and also no undervoltage warning on the rpi log. ---
**Author:** ![kingdo9](https://avatars.discourse-cdn.com/v4/letter/k/a183cd/32.png) [@kingdo9](https://rpi-rgb-led-matrix.discourse.group/u/kingdo9)\ **Post date:** [July 22, 2026, 11:01pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/fm6363c-dp32019b-flickering/1239/2 "2026-07-22T23:01:42Z")
Hi, I see on your video you were on RegType1 , can you press keyboard Right ley to next through the regtypes different configs with D15 ? Do they all flicker. on the D15 test, probably best to add -register-test-scan=32 Also please put this to SPWM\_END\_OF\_FRAME\_EXTRA\_ROW\_CYCLES=0 or SPWM\_END\_OF\_FRAME\_EXTRA\_ROW\_CYCLES=1 If you do --led-show-refresh what framerate are you getting. ---
**Author:** ![marcmerlin](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/marcmerlin/32/40_2.png) [@marcmerlin](https://rpi-rgb-led-matrix.discourse.group/u/marcmerlin)\ **Post date:** [July 23, 2026, 3:02am UTC](https://rpi-rgb-led-matrix.discourse.group/t/fm6363c-dp32019b-flickering/1239/3 "2026-07-23T03:02:19Z")
@kingdo9 a quick reminder that those env variables should really be command line arguments 🙂 ---
**Author:** ![raulzanardo](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/raulzanardo/32/869_2.png) [@raulzanardo](https://rpi-rgb-led-matrix.discourse.group/u/raulzanardo)\ **Post date:** [July 23, 2026, 12:48pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/fm6363c-dp32019b-flickering/1239/4 "2026-07-23T12:48:04Z")
> I see on your video you were on RegType1 , can you press keyboard Right ley to next through the regtypes different configs with D15 ? Do they all flicker. In the D15 all the regtypes configs flicker, only the colors change. > on the D15 test, probably best to add -register-test-scan=32 With --register-test-scan=32 still flcikers. > Also please put this to SPWM\_END\_OF\_FRAME\_EXTRA\_ROW\_CYCLES=0 or SPWM\_END\_OF\_FRAME\_EXTRA\_ROW\_CYCLES=1 Still flcikers. > If you do --led-show-refresh what framerate are you getting. 60.0Hz (lowest: 60.0Hz) ---
**Author:** ![kingdo9](https://avatars.discourse-cdn.com/v4/letter/k/a183cd/32.png) [@kingdo9](https://rpi-rgb-led-matrix.discourse.group/u/kingdo9)\ **Post date:** [July 23, 2026, 1:24pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/fm6363c-dp32019b-flickering/1239/5 "2026-07-23T13:24:01Z")
I don’t have the exact panel as yourself I either have FM6363 and --led-spwm-row-addr-type=1 or FM6373 and --led-spwm-row-addr-type=0 I think I can see a similar effect at the bottom of the display, I’m not sure if it was exactly what you are getting. The only difference between the two videos below was it was cleaner when using –led-limit-refresh=60 To the eye I can’t see issues on either, only when using a camera. Demo 15 does seem to exagerate that movement. Are you able to test it on a Pi4? ---
**Author:** ![raulzanardo](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/raulzanardo/32/869_2.png) [@raulzanardo](https://rpi-rgb-led-matrix.discourse.group/u/raulzanardo)\ **Post date:** [July 23, 2026, 2:11pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/fm6363c-dp32019b-flickering/1239/6 "2026-07-23T14:11:15Z")
> I either have > FM6363 and --led-spwm-row-addr-type=1 > or > FM6373 and --led-spwm-row-addr-type=0 I have a 128x64 FM6373C + TC7262FJ, gonna test this setup on it. > To the eye I can’t see issues on either, only when using a camera. > Demo 15 does seem to exagerate that movement. It’s hard to capture the flickering with a camera, but I’d describe it as random lines (the full line) varying in brightness by a random amount. (it this setup it shows as columns but it becouse of the “Rotate:90” mapper) I had the same bottom flickering as seeing in you second video. It was while passing through the regtypes, but it appears only in the camera, to the naked eye was fine, only the random line flyckering. > Are you able to test it on a Pi4? Yes, I am. It’s going to take a while, though—my Pi 4 is mounted on the wall. 😂 I will also test the 128x64 FM6373C + TC7262FJ matrix on it so we could have more data. Shoul I test them on a Pi Zero 2 W ? ---
**Author:** ![kingdo9](https://avatars.discourse-cdn.com/v4/letter/k/a183cd/32.png) [@kingdo9](https://rpi-rgb-led-matrix.discourse.group/u/kingdo9)\ **Post date:** [July 23, 2026, 3:06pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/fm6363c-dp32019b-flickering/1239/7 "2026-07-23T15:06:16Z")
Hmm the random line flicker I used to get that without the kernel mod. Are you on the latest version of it, as it was referred to as RT kernel, its now called optimized kernel. You can soon tell if you do cat /proc/interrupts what do you get there. Core 2 and 3 should have reduced interrupts. Zero2W I would expect you would get a similar result to Pi3, they are very similar. ---
**Author:** ![raulzanardo](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/raulzanardo/32/869_2.png) [@raulzanardo](https://rpi-rgb-led-matrix.discourse.group/u/raulzanardo)\ **Post date:** [July 23, 2026, 4:57pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/fm6363c-dp32019b-flickering/1239/8 "2026-07-23T16:57:48Z")
> Are you on the latest version of it, I’ve just pull the changes you maded a few hours ago to v0.19 > as it was referred to as RT kernel, its now called optimized kernel. Oh yeah, I see that know, the link inside `spwm.md` needs to be updated then. This is my uname -a: `Linux rpi3 6.18.24-v8+ #20 SMP PREEMPT Tue Apr 28 08:15:06 BST 2026 aarch64 GNU/Lin` With the updated version `v0.19` I’m getting and error regarding the loading of the profile My current script: ```bash #!/bin/bash export SPWM_END_OF_FRAME_EXTRA_ROW_CYCLES=0 export SPWM_FRAME_END_SLEEP_US=1 export RGBMATRIX_SPWM_PROFILE_DIR="/home/raul/apps/rpi-rgb-led-matrix_pwm_experiment/lib/spwm/registertest/data/" taskset -c 2 chrt -f 99 /home/raul/apps/rpi-rgb-led-matrix_pwm_experiment/examples-api-use/demo -D15 --led-panel-type=fm6363 --led-gpio-mapping=regular --led-brightness=30 --led-rows=64 --led-cols=128 --led-chain=1 --led-parallel=2 --led-limit-refresh=60 --led-spwm-row-addr-type=0 --led-scan-mode=0 --led-slowdown-gpio=3 --led-no-busy-waiting --led-pwm-bits=11 --led-spwm-register-config=0 --led-pixel-mapper="Rotate:90" --led-rgb-sequence=BGR --register-test-scan=32 #--led-show-refresh ``` The result: `raul@rpi3:~/apps $ sudo ./testMatrix.sh` `Size: 128x128. Hardware gpio mapping: regular` `Press to exit and reset LEDs` `Unable to load Demo 15 profiles for FM6363: unable to open register-profile catalog: /home/raul/apps/rpi-rgb-led-matrix_pwm_experiment/lib/spwm/registertest/data/fm6363.profiles` Is the profile dir config correct? ---
**Author:** ![raulzanardo](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/raulzanardo/32/869_2.png) [@raulzanardo](https://rpi-rgb-led-matrix.discourse.group/u/raulzanardo)\ **Post date:** [July 23, 2026, 5:00pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/fm6363c-dp32019b-flickering/1239/9 "2026-07-23T17:00:57Z")
> [@kingdo9](#): > > You can soon tell if you do > cat /proc/interrupts runing the D0 demo I get this: ![image](https://global.discourse-cdn.com/free1/uploads/rpi_rgb_led_matrix/original/1X/f45212fe8a663637a8ba45eca368f47b3e838cb9.jpeg) ---
**Author:** ![kingdo9](https://avatars.discourse-cdn.com/v4/letter/k/a183cd/32.png) [@kingdo9](https://rpi-rgb-led-matrix.discourse.group/u/kingdo9)\ **Post date:** [July 23, 2026, 6:50pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/fm6363c-dp32019b-flickering/1239/10 "2026-07-23T18:50:16Z")
> [@raulzanardo](#): > > ```auto > export RGBMATRIX_SPWM_PROFILE_DIR="/home/raul/apps/rpi-rgb-led-matrix_pwm_experiment/lib/spwm/registertest/data/" > > ``` I would take that bit out, you don’t really need to specify that.. the /proc/interrupts looks fine. Definitely try a Pi4 to compare. Apart from that I can’t see any issues, hard to say without the display. ---
**Author:** ![raulzanardo](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/raulzanardo/32/869_2.png) [@raulzanardo](https://rpi-rgb-led-matrix.discourse.group/u/raulzanardo)\ **Post date:** [July 23, 2026, 8:19pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/fm6363c-dp32019b-flickering/1239/11 "2026-07-23T20:19:45Z")
> I would take that bit out, you don’t really need to specify that.. I added the RGBMATRIX\_SPWM\_PROFILE\_DIR because of a warning related to the FM6363 profile: “Unable to load Demo 15 profiles for FM6363: unable to open register-profile”. The demo D15 is not working on the FM6363 > Definitely try a Pi4 to compare. Apart from that I can’t see any issues, hard to say without the display. Yep, that did, it is working fine on the Pi4. It is my Pi3B+ that is not fast enough 😞 Thanks @kingdo9! And sorry for the confunsion ---
**Author:** ![kingdo9](https://avatars.discourse-cdn.com/v4/letter/k/a183cd/32.png) [@kingdo9](https://rpi-rgb-led-matrix.discourse.group/u/kingdo9)\ **Post date:** [July 23, 2026, 9:11pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/fm6363c-dp32019b-flickering/1239/12 "2026-07-23T21:11:43Z")
Good to hear. Just tried the command with FM6363 seems fine when I run, I think a make clean make -j4 should fix it. Also make sure you got the latest update, I been doing a few very recently. ---
**Author:** ![raulzanardo](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/raulzanardo/32/869_2.png) [@raulzanardo](https://rpi-rgb-led-matrix.discourse.group/u/raulzanardo)\ **Post date:** [July 27, 2026, 11:49pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/fm6363c-dp32019b-flickering/1239/13 "2026-07-27T23:49:46Z")
It worked, thanks! I had some file access permisions problem.