I made a pcb with the CM3L compute module and TFP401A HDMI to ttl decoder. I am using the DS90C385A
ttl to LVDS driver from TI to drive a 10.1" 1280x800 IPS display from Duobond displays.
It works generally. I am getting a stable picture with expected size, no flickering and colors are displayed normally.
So it seems the h- and v-sync is working and the color channels are connected the right way.
But the display is almost unreadable. It seems that there is still a problem with the pixel clock or something else.
I have tried different hdmi_timings without success. Also different cvt modes, driver settings and so on with no luck.
I made the pcb very carefully with impedance control, 4 layers, length matching and differential pair length matching better
than 0.2 mm. So I am hoping the pcb is not forcing the problem.
In fact this is my first HDMI and LVDS design and I have no experience so far. I grabbed all informations about it from
the datasheets, Adafruit designs, reference design from TI and other resources.
It would be very helpful if someone can give me a hint for the correct display timing. There are a lot of parameters that
can be changed and I don´t know where to start.
I bought a RTD2660 driver board together with the lcd. Unfortunally the RPi is not able to readout the EEDID EEPROM.
I was hoping the chinese guys programmed the EEDID correctly so I can fetch the correct timing values but no hope
from this side. The RTD2660 is displaying the picture perfectly... Should I switch to this chip?