I'm thinking about how to couple 4 bt815 that can display 1080p but I do not see how to do. It could be super cool
Square peg, round hole. But if you wanted to engage in techno-masochism, you might consider the following:
Use a single external oscillator to drive all four BT815s
Logically OR together the RGB lines.
Connect MISO for only one BT815 (or add logic so that if only one CS is active, that MISO is connected).
Setup each one to draw 1/4 of the screen(540p). Set the front/rear porch times for each one so that each 1/4 screen is offset in the overall frame(1080p) position.
v Display1 area
_____________v horizontal rear porch
|/----\ |
|\----/ |
| |
|____________| < vertical rear porch
v Display2 area
_____________v horizontal rear porch
| /----\|
| \----/|
| |
|____________| < vertical rear porch
v Display3 area
_____________v horizontal rear porch
| |
| |
|/----\ |
|\----/______| < vertical rear porch
v Display4 area
_____________v horizontal rear porch
| |
| |
| /----\|
|______\----/| < vertical rear porch
Enable CS for all 4 BT's and enable the pixel clock. All things being good and deterministic, they should all be synced with each other,
but producing output in different quarters of the screen.
Each BT will need its own unique display list with all coordinates offset according to it's position in the output frame.
To maintain synchronisation it will probably be necessary to send the SWAP command to all 4 BT's at once.
HSYNC and VSYNC pulses should be the same on each one, so no need to OR them (just use one set).
Chopping the screen vertically 4 ways may be better than 2x2, because variations in timing will have less impact on a line-by-line basis compared to pixel-by-pixel...
...assuming the timing parameter values can be set appropriately (for any of this).
This is a terrible idea and probably won't work.
But if you really wanted to try it, this is the best approach I can think of.
If you make it work, send me pics
