FAME BOY - build log 6 - Hack Like Heck

screen issues

I'm that much out of ideas, that I've bought another display, just to check if I haven't zapped this one. Nevermind, there is an ON/OFF pin that you should definitely want to keep high now it only needs some tweaking with the colors! This will be updated tomorrow! All clear, I changed the 0x7F013 to 0x7F014 at one point and the colors were off, now that it's changed back, it works!

So I've decided on using the Mode 3 (2nd) of the pinouts for RGB565 as seen here https://www.raspberrypi.org/documentation/hardware/raspberrypi/dpi/README.md

After a while I've figured out where to solder what cable and also managed to do the device tree overlay for the PI Zero W.

So for me the following exerpt proves that the overlay works, not just for the DPI but also the PWM pins. I even get pulses on clk, vsync, hsync and DE, but the screen stays white.

pi@retropie:~ $ sudo raspi-gpio get
BANK0 (GPIO 0 to 27):
  GPIO 00: level=1 fsel=6 alt=2 func=PCLK
  GPIO 01: level=1 fsel=6 alt=2 func=DE
  GPIO 02: level=1 fsel=6 alt=2 func=LCD_VSYNC
  GPIO 03: level=1 fsel=6 alt=2 func=LCD_HSYNC
  GPIO 04: level=0 fsel=6 alt=2 func=DPI_D0
  GPIO 05: level=0 fsel=6 alt=2 func=DPI_D1
  GPIO 06: level=0 fsel=6 alt=2 func=DPI_D2
  GPIO 07: level=0 fsel=6 alt=2 func=DPI_D3
  GPIO 08: level=0 fsel=6 alt=2 func=DPI_D4
  GPIO 09: level=0 fsel=0 alt=  func=INPUT
  GPIO 10: level=0 fsel=0 alt=  func=INPUT
  GPIO 11: level=0 fsel=0 alt=  func=INPUT
  GPIO 12: level=0 fsel=6 alt=2 func=DPI_D8
  GPIO 13: level=0 fsel=6 alt=2 func=DPI_D9
  GPIO 14: level=0 fsel=6 alt=2 func=DPI_D10
  GPIO 15: level=0 fsel=6 alt=2 func=DPI_D11
  GPIO 16: level=0 fsel=6 alt=2 func=DPI_D12
  GPIO 17: level=0 fsel=6 alt=2 func=DPI_D13
  GPIO 18: level=0 fsel=2 alt=5 func=PWM0
  GPIO 19: level=1 fsel=2 alt=5 func=PWM1
  GPIO 20: level=0 fsel=6 alt=2 func=DPI_D16
  GPIO 21: level=0 fsel=6 alt=2 func=DPI_D17
  GPIO 22: level=0 fsel=6 alt=2 func=DPI_D18
  GPIO 23: level=0 fsel=6 alt=2 func=DPI_D19
  GPIO 24: level=0 fsel=6 alt=2 func=DPI_D20
  GPIO 25: level=0 fsel=0 alt=  func=INPUT
  GPIO 26: level=0 fsel=0 alt=  func=INPUT
  GPIO 27: level=0 fsel=0 alt=  func=INPUT

And here is my complete stolen together config.txt file. I've changed the frequency to 9.6 MHz as baldengineer suggested here: https://www.element14.com/community/people/baldengineer/blog/2018/03/13/screen-success

dtparam=i2c_arm=off
#dtparam=i2s=on
dtparam=spi=off

dtparam=audio=on
gpu_mem_256=128
gpu_mem_512=256
gpu_mem_1024=256
overscan_scale=1

# usb network
#dtoverlay=dwc2

# enable the DPI display
enable_dpi_lcd=1
display_default_lcd=1

# Set screen size and any overscan required

overscan_left=0
overscan_right=0
overscan_top=0
overscan_bottom=0
framebuffer_width=480
framebuffer_height=272

# set up the size to 480x272
dpi_group=2
dpi_mode=87

# set up the hsync/vsync/clock polarity and format
dpi_output_format=0x7F013

# set up the size to 480x272
hdmi_timings=480 0 40 48 88 272 0 13 3 32 0 0 0 60 0 9600000 3