I am working on rewriting one of the LCD overlays to work with a Cold Tear Electronics 7" TFT LCD, http://www.ebay.ca/itm/7-inch-TFT-LCD-module-800x480-SSD1963-w-touchpad-PWM-arduino-AVR-STM32-ARM-/121017488870. My Beaglebone Black must interface with an SSD1963 controller running in 8080 mode I believe.
The initialization code provided by the screen suppliers with some display parameters: http://pastebin.com/2xr8r8SQ. There is also code written for arduinos that have display parameters: http://pastebin.com/rNiBqNAm.
This is my current version for the LCD overlay: http://pastebin.com/F4eVPrzM.
The thing that I am stuck on is that the names of the LCD parameters in the overlay do not match the ones supplied by the manufacturer, and I’m stumped trying to figure out what it all means.
The screen works for an Arduino so I know it isn’t broken, and the way I currently have it wired up to the beaglebone the screen backlight goes on but the pixels do not change from their default state (what it looks like for a second after I turn on the arduino before the arduino outputs something to the screen).
There is also different names for pins between the beaglebone and the screen, the beaglebone has lcd_vsync, lcd_hsync, lcd_pclk, and lcd_ac_bias_en whereas the datasheet for the 8080 mode on the SSD1963 lcd controller uses D/C, WR, RD, and CS.
I’ve also had a lot of trouble getting the overlay to actually load. I have the disable hdmi and hdmin line in the uEnv.txt but when I cat slots it says that both the hdmi and hdmin capes are loaded, so I guess that is a bug. There is no problem when I echo BB-BONE-CTE to slots, after that it shows that the hdmi, hdmin, and my new overlay is loaded. The voltage seen on some pins on the beaglebone change after I load the overlay so it is doing something. I had to follow the steps here http://hipstercircuits.com/enable-device-tree-overlay-on-startup-on-beaglebone-black/ to compile the new file into the kernel and flash it on the beaglebone. I am using the Angstrom SD card image from 2013/08/21 with the 3.8.13-bone30 kernel with the new overlay in it.
Any advice or insight is greatly appreciated!