Shop OBEX P1 Docs P2 Docs Learn Events
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: 15,933

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

  • RaymanRayman Posts: 15,933

    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: 15,933

    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: 15,933
    edited 2026-01-01 19:45

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

  • RaymanRayman Posts: 15,933

    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...

  • roglohrogloh Posts: 6,213

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

    Hopefully you didn't damage it in the process by perhaps shorting 5V somewhere it didn't like.

    1080x1080 is an unusual resolution. I'm not sure that cheap VGA to HDMI adapters would do that conversion. You might have to scale down the input from 1920 to 1080 horizontally. But if the 5 inch display simply takes a regular 1920x1080 signal to begin with and does that scaling for you it might be okay. Is that how it works, it scales 1920 down to 1080? Or does it show the centre 1080 pixels of the 1920 horizontal pixels you provide? I've not used these circular displays before.

Sign In or Register to comment.