Sorbus 32x32 LED Display

The panels built so far use this order of LEDs.

Hardware Setup

The LED hardware is a single string of 1024 WS2812 LEDs created by concatinating four 16x16 WS2812 panels, which are available on AliExpress or eBay. The order in the hardcoded translation matrix within the software looks like this:

LED order

Note the first LED is roughly at the middle on the left side. If the order of the LEDs is different in your setup, you need to create a new translation matrix. An example on how to create one is available as part of the source code: src/tools/translation_matrix.c.

I/O Registers

I/O utilizes the page $D3xx. All registers are write only, as the hardware only sniffes the bus and never actively drives it.

  • $D300: DMA into framebuffer and flush (strobe register)
  • $D301: DMA into framebuffer without flush (strobe register)
  • $D302/3: start address of RAM source
  • $D304/5: startpixel of framebuffer target (10 bit, absolute address)
  • $D306/7: startpixel of framebuffer X/Y format (5 bit each)
  • $D308: width of DMA in pixels-1 (5 bit, $00=one pixel, $1f sets a full line)
  • $D309: height of DMA in pixels-1 (5 bit, $00=one line, $1f sets full height)
  • $D30A: linestep of source in pixels-1 (8 bit)
  • $D30B: transparency color
  • $D30C: colormap

  • $D30D: custom colormap id register (valid value: 1-3)

  • $D310: red color for custom colormap

  • $D311: green color for custom colormap
  • $D312: blue color for custom colormap

(defaults are starting at $d302: $00,$cc,$00,$00,$00,$00,$1f,$1f,$1f,$00,$00)

If not all bits of a register are required, those will be masked out/ignored.

All addresses have been named nicely in fb32x32_regs.inc. For convenience, you can just .include 'fb32x32.inc' which will include everything useful for writing effects: BIOS call, I/O addresses and fb32x32_regs.inc.

Copy Mode

Value written do $D300/1 indicades mode (can be or'ed together):

  • $00: plain copy
  • $01: transparency: no copy when source color = transparent
  • $02: transparency: no copy when destination color = transparent
  • $04: transparency: only copy when destination color = transparent
  • $06: do nothing

Color Palettes

Color Description Example
$00 Insane's RGBI2222 example
$01 Custom 1
$02 Custom 2
$03 Custom 3
$04 C64 like example
$05 C16 like example
$06 Atari 8-bit like example
$07 Atari 8-bit like, ordered differently example
$08 Veto's custom curated example
$09 Coder colors (C128 VDC like) example

Note that the example colormaps do not reflect the correct brightness of the colorvalues. Those are just the same values converted to RGB.

Custom defined color palettes are always specified in RGB444. Writing to $D30D resets internal index of $D310-$D312 to $00, when a colorvalue is written, lower 4 bits will be taken as value for this index, and the index will be incremented. Once $100 color values has been written, that color slot does not take new color values. Adding $80 to the index value will fill the palette in reverse order starting with $ff going down. If a value other than $01-$03 and $81-$83 is written to $D30D, then $D310-$D312 will not accept any data.

Also selecting the colormap by writing to $D30C copies the palette to the "current palette", so only then the data is updated not during writing to $D310-$D312.

Since the board just sniffes the bus, DMA from internal drive or swap pages is not detected.