Quite nice. Iād say just about perfect, in fact. 24-bit RGB plus SPI, which means youād need an MCU with an LCD driver, or an external driver IC, I assume? Is this a ānormalā TFT interface?
Pretty standard yes. Iām looking for a display for the Hydra, which has an LCD driver built into the CPU. But no Gadgeteer board can do 24 bit color, only 16 bit. The SPI interface is only to config parameters on the LCD, not for display data. I think the original Cobra display was also like this and the display PCB had a small CPU on just to load the config into the display.
There are plenty of pure SPI displays, but that might be too slow for Skewworksā game engineā¦
I think that you can drive a 24-bit display at 16-bits by simply leaving the lowest bits of each channel unconnected, is that accurate? In that case, this could work with Hydra and Spider.
What are our options for an external driver for Cerberus and USBizi?
You have to connect the unused pins to ground, or you can connect the lowest pins together. Technically this is the best.
Cerberus and USBizi does not have enough ram. We have trouble using the OLED display with Cerberus, which has double the memory of the USBizi. And the OLED is 128x128. You will have lots of pain using a 320x240 display with Cerberus.
Right; I was thinking that one could use an additional MCU+RAM to act as a display driver. Clever firmware could be created that would parallel the old āWindows Acceleratorā graphics cards of back in the day. They took simple commands (draw a line here, a circle there, fill in this polygon with that color) that made drawing much faster. You could even implement Glide in the firmware, and just send your XML over to it to have it drawn.
The ācontrollersā themselves are in the $10-$15 range. If my DigiKey-fu was better, I might be able to figure out how to search for microcontrollers which include TFT control hardware, but I canāt, sadly.
Yes, basic controllers, like the ones from Epson, but the 4D Systems displays are EXPENSIVE.
RS Components sells 4D Systems stuff. Just the graphics engine module is $110. A 1.5" OLED display is $135. A 2.4" OLED is $300. You get the picture. And I know that RS is expensiveā¦
And the basic controllers do not have any acceleration. Then you can just as well look at a display like the one that used to be on the Panda Touchā¦
Right. I think it would be necessary to track down the cheapest MCU that can drive the TFT directly, and a bit of DRAM to go with it. From there, itās all firmware.
Well, kinda, but the ARM9 on the Hydra is massive overkill. Iām thinking a Cortex-M of some sort has to exist, that can be had for $2-$5 that can drive an LCD. The SRAM can be had for $5 or so, I believe?
At least some of STās Cortex-M3 chips have an āFSMCā (Flexible Static Memory Controller). ST even has an app note on driving LCDs with it, though they do say itās not ādedicated TFT hardwareā.