I have a BBB running Debian Wheezy, kernel 3.8.13-bone70. I have a 4D systems LCD cape that I can attach to my system and the LCD cape will start up and run without any problems. The display datasheet is here.
I’m trying to make a custom cape using the same display. My custom cape does not have the LEDs, power, reset, up, down, left, and right buttons, as well as no EEPROM. I have verified my own schematic comparing the relevant points, and everything seems to check out. I have also verified that my display pinout matches the circuit board(s).
The kernel can be forced to load the cape in the uEnv.txt file. I have modified this file to load the cape on startup.
What I’m seeing is as follows:
After the OS has loaded, the PWM for the display backlight is actually triggering on the heartbeat. My pins are correct schematically, I’ve verified this. The PWM output is actually triggering on the heartbeat, I’ve verified this using a multimeter and probing the output from the BBB. Also, there is no backlight created in the /sys/class/backlight directory.
After disabling the trigger on the backlight, I just set the backlight to output the max value. However, nothing is showing up on the screen.
I have also noticed that the the 4D systems cape actually loads the 00A1 revision of the overlay, but the uEnv.txt file tries to load the 00A0 revision. I did not have the 00A0 revision, so I copied the 00A1 file and re-named it as the 00A0 file. The cape manager accepted this and loaded the file. Is there some way to specify loading the 00A1 revision?
Is there some way to capture the pinmux of the LCD cape and store it to re-load with my custom cape?
Are there any other suggestions about what I’m possibly doing wrong?
Thanks in advance.