Hello Folks, I need some help,

Nick_Tracy · October 19, 2016, 12:49am

Hello Folks, I need some help, I need recommendations on how to implement a grid layout of WS2812Bs. Problem is my grid is a serpentine layout with the first row starting from the right and going left, instead of the normal way where the first pixel is on the left and the string cascades right. Also on top of having a backwards serpentine layout, I also don’t have a perfectly square grid, the top row is shorter by one pixel on either side then the rest of the grid.
I’ll try to lay this out ASCII style:

– --6—5---4—3----2----1-- –
/
–7—8---9—10–11–12–13–14–
/
-22-21-20–19–18–17–16–15–

and so on…

Any ideas? Also, I want to be able to do scrolling text on this grid among other things, whats the best way to implement scrolling text from a string?

marmil · October 19, 2016, 1:14am

Have a look at how @Garrett_Mace did XY mapping for his cool shades with a odd shaped grid.

github.com

macetech/RGBShades/blob/master/XYmap.h

// Helper functions for a two-dimensional XY matrix of pixels.
// Special credit to Mark Kriegsman
//
// 2014-10-18 - Special version for RGB Shades Kickstarter
//              https://www.kickstarter.com/projects/macetech/rgb-led-shades
//              2014-10-18 - code version 2c (local table, holes are r/w), 
//              by Mark Kriegsman 
//
//              This special 'XY' code lets you program the RGB Shades
//              as a plain 16x5 matrix.  
//
//              Writing to and reading from the 'holes' in the layout is 
//              also allowed; holes retain their data, it's just not displayed.
//
//              You can also test to see if you're on or off the layout
//              like this
//                if( XY(x,y) > LAST_VISIBLE_LED ) { ...off the layout...}
//
//              X and Y bounds checking is also included, so it is safe
//              to just do this without checking x or y in your code:

This file has been truncated. show original

Also, have a look at @Aaron_Liddiment 's custom matrix library stuff. His LEDLatrix can probably reverse your backwards serpentine in code, or at least give you some pointers.
And his LEDText does text scrolling.

Amelia_T · October 19, 2016, 1:59am

I was JUST about to ask a similar question!

I put 8 strips of WS2812B pixels 15/strip on an umbrella and I’m treating it like a matrix. Even though it’s straightforward (8x15), it starts at the bottom left. The adafruit neopixel matrix library has this option and uses text in the example. I just ended up mapping it out since I couldn’t find a way to tag one of the corners as the starting point; the RGBShades xymapping was really helpful.

I’m still figuring out my sketch (mainly due to wanting to run when I’m just learning to walk) so these tips are SUPER helpful.

Nick_Tracy · October 19, 2016, 2:44am

Thats great, its hard to find answers to these strictly using google so thats why i asked. Ask and you shall receive! lol thank you very much for the info. I’ll give it a try.

Charity_Stolarz · October 19, 2016, 4:04am

I used the RGB shades mapping for my heart matrix costume and it worked well. The code is on here somewhere if you search Bright Top

Nick_Tracy · October 20, 2016, 3:51am

I’m so happy someone gave me the clues. Once i saw that code I realized all i had to do was remap the LED order in a different table that the main function “XY(x,y)” would use to correctly return the correct LED address. It was so simple I don’t know why I didn’t think of it before. but I’m glad I asked. The ShadesMatric helper code took care of my reverse order and odd grid shape. Pro Tip: Laying out the actual shape of your matrix in the table array helps you visualize your design and helps you see where the pointer should point. Now on to getting the scrolling text to work.

Nick_Tracy · October 20, 2016, 6:57am

Ok so I’ve been playing with the LEDMatrix and LEDText libraries, they haven’t been updated in a year seems he hasn’t been maintaining the code much recently. but, I see a function called SetLEDArray and you pass it a struct CRGB. I’m guessing this is where I would create a custom LED array table with the remapped addresses? but I’m not sure how I set that up. Do i declare an array with a name and then pass that name in to the function somewhere in the setup loop?

Charity_Stolarz · October 20, 2016, 11:38pm

@Nick_Tracy Look at this code https://github.com/macetech/RGBShades/blob/master/XYmap.h. It shows how to set up the xy map and also has scrolling text effects