I am in the very early stages of interfacing the BBB with a new 4.3" TFT LCD, not a cape. It has a 16-bit data bus setup for 6800 style interface with the onboard controller (SSD1963). This winds up requiring 22 GPIO pins. I have been an engineer in the LCD industry for 6 years now, so I know my way around most types of LCDs and configurations…but I am a relative newbie to the BBB.
I have disabled the HDMI port in the uenv.txt file and have confirmed it to be disabled. The 6 control lines are connected to P8 pins 9-14, and the 16 data pins are connected to P8 pins 29-44. 3.3V power is taken from P9 and GND is taken from P8. When I physically connect the display to these pins, the board does not boot. I get an LED to come up but then it seems to pause and never boot. The display requires a max current of 220mA which I know is close to the limit for the 3.3V supply, so I left the connections made, but removed the power to the LCD. Same issue. I checked for shorts on the connections…none that I could find. There is NO buffer between the LCD and the uC as the boards have not been spun yet. I am hooking it up using an FPC-to-wire converter cable.
Given my relative noobishness to the BBB hardware, I was hoping someone would have some fundamental oversight I am making here.