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P2 - HDMI and Waveshare 5" display — Parallax Forums

P2 - HDMI and Waveshare 5" display

Brian_BBrian_B Posts: 844
in PASM2/Spin2 (P2)

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?

Comments

  • Wuerfel_21Wuerfel_21 Posts: 5,756

    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)
  • RaymanRayman Posts: 15,932

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

  • RaymanRayman Posts: 15,932

    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_21Wuerfel_21 Posts: 5,756

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

  • RaymanRayman Posts: 15,932

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

    IMG_5511.jpeg
    480 x 640 - 213K
  • Brian_BBrian_B Posts: 844
    edited 2026-01-01 18:04

    1080x1080 , but after i tried It with the 5 volt jumper wire it won't even work on the RPI.

  • VonSzarvasVonSzarvas Posts: 3,623
    edited 2026-01-01 18:34

    The newer rev of the hdmi addon has pads labelled near the hdmi socket for adding a 1k resistor or jumper/shunt.

    BUT… first be sure that your breakout board is outputting 5V at the accessory headers.

    That usually means the breakout is powered by 5V (and not a higher voltage). And also that the breakout board has the 5V outputs enabled.

    To verify, measure the 5V output pin on the breakout board header before attaching the addon.

  • RaymanRayman Posts: 15,932
    edited 2026-01-01 19:45

    P2 can't drive 1080x1080 HDMI display directly. 800x480 is close to the max.

  • RaymanRayman Posts: 15,932

    Suppose there's a chance that a VGA--> HDMI adapter would work. That could signal 1080p which may or may not make the display happy...

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