P2 - HDMI and Waveshare 5" display

Brian_B

Hi,
I have a 5" round waveshare hdmi display and I have the P2 running the the spiral hdmi demo, it works on a normal hdmi display but doesn't work on the waveshare. I know the display works as i plugged it into RPI. Any thoughts on why the waveshare won't display it?

Wuerfel_21

Possible issues:

• Display does not like the pin drive mode used (try replacing the line that says wrpin ##%001001<<8,#7<<6 + hdmi_base 'set 1k-ohm drive on HDMI pins with wrpin ##P_REPOSITORY|P_OE|P_LOW_FAST|P_HIGH_1K5|P_SYNC_IO, #hdmi_base addpins 7
• Specialty display wants special resolutions (try this on a PC or something - does it actually take 640x480 modes?)
• Some sort of exciting protocol incompatibility (not sure if chip's example is 100% spec compliant)

Rayman

What is display resolution?
Looks like might be 800x480…
That might require code tweaks

Rayman

Also it might be the 5v signal. Some displays seem to need it. The parallax adapter needs a jumper wire added to provide that…

Wuerfel_21

Oh the 5V pin, that's the No. 1 thing to check actually. Some sinks will not turn on without that. Simple electrical fix.

Rayman

Here's an example of the jumper wire... Could also be a resistor instead of a jumper, like 1k or so...