Can't compile for Kuman 3.5'' TFT

[spaghiajoeojo]

Hi, my display is a kuman and I can't compile the driver to speed up its framerate. I found this in official driver cd:

3.5 inch touch screen datasheet V1.0.pdf

I tried ILI9486 and ILI9486L but I can't really say what pin is Data Control. For what I see it can also be an ILI9488L... can you help me?

[juj]

Unfortunately I have not tested Kuman displays. If it is this one http://www.kumantech.com/kuman-35quot-inch-480x320-rgb-tft-lcd-pixels-touch-screen-with-touch-pen-for-raspberry-pi-3-2-model-b-b-a-a-module-spi-interface-sc06_p0014.html , then it resembles the KeDei display a lot, which was discussed in #40.

To try the KeDei driver in hope the Kuman display and KeDei displays might be clones of each other, run CMake with -DKEDEI_V63_MPI3501=ON setting, and a relatively safe SPI speed to start with, e.g. -DSPI_BUS_CLOCK_DIVISOR=30.

[spaghiajoeojo]

Sadly it doesn't work with Kedei preset...

In /boot/config.txt I found

# Additional overlays and parameters are documented /boot/overlays/README

# Enable audio (loads snd_bcm2835)
dtparam=audio=on
dtoverlay=waveshare35a
#dtoverlay=ads7846,cs=1,penirq=17,penirq_pull=2,speed=1000000,keep_vref_on=1,sw$
hdmi_force_hotplug=1
#max_usb_current=1
hdmi_group=2
hdmi_mode=1
hdmi_mode=87
hdmi_cvt 480 320 60 6 0 0 0
hdmi_drive=2

So I tried -DWAVESHARE35B_ILI9486=ON but nothing changed :(

[juj]

Then it looks like Kuman displays fall outside fbcp-ili9341 support. If you are able to reverse engineer the protocol, you can try cross-referencing the support against existing drivers, e.g. the KeDei or the ILI9486/ILI9486L ones, perhaps one of those can be modded to work also on Kuman displays.

[juj]

I'll mark this retired, but keep it open, so that other people will see that Kuman displays have been observed to not work well. Thanks for reporting!

[juj]

Youtube user haveallgames documented that the current KeDei backend does not seem to be able to support all KeDei displays, his results are at https://www.youtube.com/watch?v=fzNl4dB_Vis and https://www.youtube.com/watch?v=FrldurB37QM . It is hence possible that even if the Kuman display you have is same or similar to the KeDei display, that there is some notable difference that fbcp-ili9341 is not currently able to take into account, that is causing an issue here as well.

[WiredLife]

cmake -DWAVESHARE35B_ILI9486=ON -DSPI_BUS_CLOCK_DIVISOR=25 -DDMA_TX_CHANNEL=9 -DDMA_RX_CHANNEL=6 -DSTATISTICS=0 ..

works for my Kuman 3.5'' TFT @ Raspberry Pi 4B 1G

[spaghiajoeojo]

Thanks to @WiredLife works for me too:

cmake -DWAVESHARE35B_ILI9486=ON -DSPI_BUS_CLOCK_DIVISOR=25 -DDMA_TX_CHANNEL=9 -DDMA_RX_CHANNEL=5 -DSTATISTICS=0 ..

on raspi 3 B and raspbian

[spaghiajoeojo]

Can you unset this as "retired" please? @juj
It is working on Kuman 3.5" 😃

[juj]

Nice! Good info and great testing here!

[WiredLife]

here some tips
use #define ALL_TASKS_SHOULD_DMA to safe cpu
and #define NO_INTERLACING to get a good picture on videos

btw you can go up to -DSPI_BUS_CLOCK_DIVISOR=24 but NOT -DSPI_BUS_CLOCK_DIVISOR=23

@spaghiajoeojo do you get more as 10 fps on video?
maybe someone has a tip to get higher fps?

[spaghiajoeojo]

According to the guide of @juj DSPI_BUS_CLOCK_DIVISOR should be an even number, I managed to set its value to 16 and core_freq to 280 in boot/config.txt. Since my pi is used mainly to stream from my main pc it runs smoothly at 30-40 fps interlaced. I can play GTA5 running with steam link on a marvelous 480x320 display!

[WiredLife]

ok its NO_INTERLACING
if i enable interlacing again, i get higher fps
but the lines on movement are not so nice
so i'm using #define NO_INTERLACING without #define ALL_TASKS_SHOULD_DMA
because cpu load is ok (lower as interlaced mode) and with #define ALL_TASKS_SHOULD_DMA i get lower fps

my max speed setting with all working fine is that:
BCM core speed: current: 500000000hz, max turbo: 500000000hz. SPI CDIV: 24, SPI max frequency: 20833333hz

@juj is it possible to minimize the "interlacing lines" on fast movement?