Max framerate

[Lukaswnd]

How hard would it be to implement a max framerate feature?
When you lower the PIXEL_COLOR_DEPTH_BITS and don't have a huge panel combination, you might endup with a very high framerate.
I know due to DMA there is not much overhead for a higher framerate. But on one hand it feels wrong have 400hz and on the other hand it should be possible to incease the OE time (time how long each row of leds is turned on) resulting in a brighter display.

Ofcourse you could reduce I2S speed, but I like to have my display brighter.

I currently have no idea how to implement this and I don't want to spend my time on this now, maybe someone else gives it a try.

[mrcodetastic]

The framerate is a function of the data bitrate (dma i2s speed). Using the lowest clock rate + highest panel brightness level should do the trick.

I am not keen on implementing any dynamic configuration on the DMA hardware side of the library based on color depth, resolution etc. as it's a pain to debug and adds unnecessary complexity.

[Lukaswnd]

Yeah, that is what I thought too much work for little result

[board707]

it should be possible to increase the OE time (time how long each row of leds is turned on) resulting in a brighter display.

@mrfaptastic, correct me If I am wrong, but as I understand the framerate has nothing to do with panel brightness.
OE sets the fraction of time from the total cycle length in which the diodes are lit. OE time is a relative value, it does not depend on the duration of the cycle itself and therefore the framerate does not affect the brightness

[board707]

@Lukaswnd

Then we have 5 subrames each frame.
Subframe1: shift data of first bit (leds on)
Subframe2: show (oe) subframe 1
Subframe3: shift data of second bit (leds on)
Subframe4: show (oe) subframe 3
Subframe5: show (oe) subframe 3

You do not quite correctly represent the work of the matrix. You assumed that at the moment of loading a next bit of data( Subframe1 and 3 in your scheme), the diodes on the matrix are turned off. But it is not.
In fact, the loading of a new subframe occurs DURING the exposure of the previous one:

Subframe1: show (oe) bit1, shift data of bit2 (leds on)
Subframe2: show (oe) bit2 , shift data of bit3 (leds on)
Subframe3: show (oe) bit2
Subframe4: show (oe) bit3 , shift data of bit1 (leds on)
Subframe5: show (oe) bit3
Subframe6: show (oe) bit3
Subframe7: show (oe) bit3

[mrcodetastic]

That makes sense.

Check out the 'brtCtrlOEv2' function as that was recently updated by another contributor to enhance the brightness control. Not really an area that I have touched upon to be honest.

[Lukaswnd]

@board707 oh I didn't know that. Thank you for explaining

[daveythacher]

The brightness loss is minimal when properly configured. At high refresh rates brightness reduction is expected.

This code base does not support refresh rates about 240-250Hz. The frame rate can be up to this value however the CPU may limit this. Note I would limit to 120FPS.

[daveythacher]

Correction: This code base does not support refresh rates above 240-250Hz.