LUT as LUT, Streamer, Pins - supported modes & RAM

Now the LUT as RAM has settled down, I'm looking at LUT as LUT.

If we take a real example, and start simple :

800x480 is a common modern LCD display, with a choice of resolutions.

using a 4b pixel and a 32b Lookup, RAM Bytes needed are

4bp : 800*480*4/8 = 192000
8bp : 800*480*8/8 = 384000
16bp: 800*480*16/8 = 768000 (Outside current HUB budget)

From what I can see in the DOCs, 4 & 8b LUT indexing are possible, and 16b can feed direct (skip LUT)

If you want less than Digital 32b out, DOCs say
	        1000 = enable output on pins 31..0      32 pins
	        1001 = enable output on pins 39..8      32 pins
	        1010 = enable output on pins 47..16     32 pins
	        1011 = enable output on pins 55..24     32 pins
	        1100 = enable output on pins 63..32     32 pins
	        1101 = enable output on pins 63..40     24 pins,  8 MSBs not output
	        1110 = enable output on pins 63..48     16 pins, 16 MSBs not output
	        1111 = enable output on pins 63..56      8 pins, 24 MSBs not output
Which pins have the boot SPI & UART ? Is there a conflict in 42,16,8b modes ?

8bp is perhaps the most natural choice, but even that is not great for colour blend backgrounds - you can see the steps instead of gradient.
It also wastes half the LUT, which otherwise just sits there....
4bp is quite spartan, even with a lookup table.

Besides those simple choices, there are a couple of others, which the P2 resource might naturally support = 6 & 10 bit pixels ?
4bp :  800*480*4/8  = 192000 (std)
6bp :  800*480*6/8  = 288000 Packed
6bp :  800*480*(32/5)/8  = 307200  5 pixels per u32
8bp : 800*480*8/8  = 384000 (std)
10bp: 800*480*10/8  = 480000 Packed  2^19-800*480*10/8 = 44288 Spare
10bp: 800*480*(32/3)/8 = 512000    2^19-800*480*(32/3)/8 = 12288 Spare

4,6,8 index the LUT easily.
10b would work well as a 1024 x 16 LUT, but DOCs are unclear if there is a 1024 x 16 mode ?
This is 4 times as many choices, as 8 bp, and it more fully uses LUT and HUB memory.

Unpacked versions of 6,10 bp simply fill the u32 and discard the leftover.
Packed versions use less RAM, but require a simple 6,10 bit collector for the left over bits.

At 10 bp, packing makes a big difference going from 12288 free bytes to 44288 free bytes.

Is it possible to add 6,10bp to Streamer to better match available / mainstream displays ?

Comments

  • Re: 24,16, & 8 bit streamer modes.
    I encountered this "conflict" of the upper 4 bits in a early experiment.
    I was sure I posted something about this but a search fails to find any matches.
    Anyhow, I suggested maybe the 24,16 & 8 bit modes be relocated to the top of PortA.
    Maybe this has changed now that Chip has added 4,2 & 1 bit modes in the next release.
  • You did post something. Wasn't there something about being able to slide the 32 bits 8 bits at a time or something?
  • jmgjmg Posts: 14,567
    Tubular wrote: »
    You did post something. Wasn't there something about being able to slide the 32 bits 8 bits at a time or something?

    That much is in the data, but they slide-up, then compress.....

    One SDRAM solution could need 4b + 16b+16b Streamers, not clear how that can MAP to pins either ?
    ozpropdev wrote: »
    Maybe this has changed now that Chip has added 4,2 & 1 bit modes in the next release.

    Hopefully the data is just delayed relative to the design ....
  • ozpropdev wrote: »
    Re: 24,16, & 8 bit streamer modes.
    I encountered this "conflict" of the upper 4 bits in a early experiment.
    I was sure I posted something about this but a search fails to find any matches.
    Anyhow, I suggested maybe the 24,16 & 8 bit modes be relocated to the top of PortA.
    Maybe this has changed now that Chip has added 4,2 & 1 bit modes in the next release.

    For streaming: 32-/16-/8-pin groups can start at any 8-pin offset (0,8,16,24...), while nibbles can start at any 4-pin offset, twits can start at any 2-pin offset, and single pins can be anywhere.
  • With twits, maybe single bits should be called nits ;)
  • Cluso99 wrote: »
    With twits, maybe single bits should be called nits ;)

    And no bits could be called zits.
  • ROFL ;)
  • How are the compilations going?
    Back in Oz Wednesday so rearing to go :)
  • jmgjmg Posts: 14,567
    cgracey wrote: »
    For streaming: 32-/16-/8-pin groups can start at any 8-pin offset (0,8,16,24...), while nibbles can start at any 4-pin offset, twits can start at any 2-pin offset, and single pins can be anywhere.
    Cooll, sounds like you can activate as
    4b + 16b + 16b Streamers,
    which looks like one way to get decent SDRAM speed.

    rogloh has worked out a compact frame sequence using P1V for R/W and refresh, so it looks like SRAM.

    I think that could 'play-back' in a streamer ?
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