I'm looking for suggestions regarding a P2 touchscreen SBC. I've worked on several revisions of the "touchburger" trying to free up pins while keeping the memory access quick but have never found an actual excuse to make a pcb run. (I'm Average Joe btw
) I still have a couple working touchburger boards but would really like an excuse to make a pcb run. Some thoughts for this design :
P2 Module : TBD
It sounds like the initial release of chips will be on a carrier board so knowing the details of the carrier board will dictate the support circuitry required. Assuming a P2D2 module or similar it should include everything needed.
Memory : 16Mb (1M x 16) Parallel 55ns 48-TSOP I @ $10.46
The original touchburger uses 2x AS6C4008 4MB 512kb X8 SRAMs. I was looking at moving to 1 x 16MB 1M X16 but this really isn't a lot of memory, about 2 full screen 800x640 images. I'm keeping the 16 bit data bus as it's handy with the displays. I've considered SDRAM but since I've never interfaced with drams i'm a bit iffy, maybe I could put a SRAM and SDRAM sharing the 16 bit data bus. I've looked at parallel FLASH as well, I know it seems pointless if you have a removable SD card but it would be nice to not need to load images from the sd. From the user interface perspective, loading a full screen 640 x 800 image from SD is painful.
?? SDRAM ?? FLASH ??
CPLD (for glue logic) : XC2C64A-7VQG100 @ $4.75
I've already tested this cpld for the previous version, worked great but the board space saving was a trade off with the extra 1.8v supply necessary. Since the p2 will need 1.8v core logic supply..
Touchscreen : Any SSD1963 or SSD 1289 or ?ili9341? touchscreen module.
There's some variations to the 40 pin "universal" connector. I'd like to have different modules without using the wire jumper method I've resorted to in the past.
Form Factor : TBD
I was considering using the same form factor as the 7" touchscreen but in early layout tests this left a large empty board area.