1/4, 1/8 scan panels

[mrcodetastic]

Four-scan panels (aka. '1/8' on a 32px high LED matrix) use the same HUB75 connector and can be connected to the ESP32 in the same way as a 'half scan' (aka. '1/16' for a 32px high LED matrix, or '1/32' for a 64px high matrix), but additional software logic (pixel remapping) is required or the display will show garbage.

Four Scan Panel (aka. '1/8' on a 32px high LED matrix ) - Thank you to The Electronic Engineer for a 'four scan' (1/8) panel to get this to work.

For any other panel of a random scan type that doesn't work:

• Somebody with these panel types needs to help code a solution; or
• Sends us links to existing code (the specific code) that works with these panels (perhaps can easily copy paste) - lots of trial-and-error will be required from you to help find a solution; or
• Simply send the contributors to this library a spare panel you might have so we can try code and test a solution ourselves.

[tsctrl]

can this changes be integrated to the main branch? wondering how to re purpose existing virtual class than creating new instance for 1/8. the idea is to reuse existing virtual class but provide different initialization implementation that can be swap by configuration

[danieldecesaro]

Dear @mrfaptastic,
In a issues #154. I reported the issue I was having with a 1/8 panel where the line was of only 16 LEDs and not 32 as you solved in the post in question.
Last week I thought about fixing this and fixed the problem with some small modifications to your library.
Are they:
enum PANEL_SCAN_RATE {NORMAL_ONE_SIXTEEN, ONE_EIGHT_32, ONE_EIGHT_16};
``
if ( _panelScanRate == ONE_EIGHT_16)
{
if ((y & 8) == 0) {
coords.x += (panelResX>>2) * (((coords.x & 0xFFF0)>>4)+1); // 1st, 3rd "block" of 8 rows of pixels, offset by panel width in DMA buffer
} else {
coords.x += (panelResX>>2) * (((coords.x & 0xFFF0)>>4)); // 2nd, 4th "block" of 8 rows of pixels, offset by panel width in DMA buffer
}

	if (y < 32)
		coords.y = (y >> 4) * 8 + (y & 0b00000111);
	else{
		coords.y = ((y-32) >> 4) * 8 + (y & 0b00000111);
		coords.x += 256;
	}
}

`
This apparently solved the problem and I managed to make a 4 panel dislay work perfectly, evidence follows;

• 1/8 lines of 32 LEDs
  

• 1/8 lines of 16 LEDs
  

[mrcodetastic]

Hi @danieldecesaro,
Fantastic work with that. Would you be able to raise a pull request or attach the modified virtual display class file if that's easier, and I'll incorporate.

[danieldecesaro]

Hi @mrfaptastic,

  Yes I can, I will do it soon!

Att.

[danieldecesaro]

Hi @mrfaptastic,
I just posted a proposed change, see if it's satisfactory. Thanks!

[danieldecesaro]

Dear @mrfaptastic,
I'm doing more tests with different types of panels and I found a bug in the 1/16 scan panels.
In version 2.0.3 of the lib everything works perfectly, in version 2.0.6 or even in the master there are distortions in this type of panel. Evidence follows:

I point out that I'm using a 2x2 setup but I see the same problem on individual panels as well. Using VirtualMatrixPanel, of course.

Can you guide me on what I should focus on to solve the problem?

Regards,

Daniel de Cesaro

[mrcodetastic]

Have you tried changing the mxconfig.clkphase = false; config para to true or false and seeing that that makes a difference?

Some panels need an inverted (or not inverted) clock... causes stuff to be offset by a pixel on the x-coord.

Similar to the common issue raised in: #134

[danieldecesaro]

Hi @mrfaptastic,
Problem solved, thanks.
Att.

[board707]

Hi @mrfaptastic,
the problem with panels 1/4, 1/8 and similar is that for each type, for example 1/4, there are many variants for addressing rows and columns. Thus, it is impossible to write one code that will fit any matrix 1/4, there are dozens of variations. I work with such matrices, but for each one you have to choose it own version of the coordinate transformation

[stsm1964]

Hi, I am new in this discussion.
Is there any new development on the 1/4 scan panel?
I am currently using "lefty01" 1/4 scan code to test my 32x16 1/4 scan LED module and run into issues.