Shop OBEX P1 Docs P2 Docs Learn Events
Prop output to VGA screen in laptop? — Parallax Forums

Prop output to VGA screen in laptop?

John KauffmanJohn Kauffman Posts: 653
edited 2010-11-13 05:23 in Propeller 1
My experiments with the prop output to VGA are going great using a spare VGA monitor. But I sometimes develop on my prop outside the house with just my laptop (no external VGA monitor).

Is there a way to feed Prop VGA output back into my laptop screen to display on the laptop screen?

Thanks.

Comments

  • RaymanRayman Posts: 14,889
    edited 2010-11-12 14:38
    If you're brave, you can try the "Prop Monitor" app on my website:

    http://www.rayslogic.com/propeller/Programming/PropMonitor/PropMonitor.htm
  • John KauffmanJohn Kauffman Posts: 653
    edited 2010-11-12 15:53
    Where is the bravery needed on a scale of:
    Probable fried laptop......................................Minimal comments in code
    Thanks.
  • RaymanRayman Posts: 14,889
    edited 2010-11-12 17:01
    I'm just kidding... (mostly) I'm sure it's fine. :)
  • GreyBox TimGreyBox Tim Posts: 60
    edited 2010-11-12 18:39
    What you are asking to do is not possible without a viewer application on the PC (what rayman has suggested). The graphic processor in the laptop is not designed with a bi-directional VGA interface, it is only a DAC (digital to analog). You'd need a video decoder in the PC for the GPU to even understand the content you'd be pushing into it (ADC + sync logic + frame buffer).

    Your laptop's LCD is a completely different piece of hardware than a VGA display - all digital (usually LVDS). That being said, you may have luck cracking open the laptop and wiring directly into the LCD's LVDS bus - but I doubt the Propeller I will have enough perfomance to directly drive a large LCD. An 8.9" netbook screen with 1024x800@60Hz/18-bit color + sync/DE/clock/power-control/backlight-control requires 24 parallel bits out for the interface (almost all of your pins) running at ~67MHz (which I doubt you can do, even with assembler):

    FP Sync BP Active Total
    56 104 160 1024 1344 Horizontal
    3 10 18 800 831 Vertical

    1344 * 831 * 60 = 67,011,840 clock/data output-cycles per second (Hz)

    -T
  • John KauffmanJohn Kauffman Posts: 653
    edited 2010-11-12 19:24
    Tim:
    Thanks for analysis. Laptop is still my main machine, so I'm not into dissection. Your description of how it might be done is above my level, but I'm re-reading again and again to glean some knowledge. THanks.
  • John KauffmanJohn Kauffman Posts: 653
    edited 2010-11-12 19:31
    Rayman
    The Demo worked fine, much thanks. Now I can get back to coding in the backyard.
    Is there a way to make the window larger? Currently shows as about 10cm wide and 15 cm high.
    THnaks.
  • potatoheadpotatohead Posts: 10,261
    edited 2010-11-12 21:45
    One great alternative here is to use TV graphics and a capture card. That's what I do. VGA has better resolution characteristics though. Just thought I would toss that out there, because it's really easy and flexible.

    **wishing laptops had a VGA in, myself
  • prof_brainoprof_braino Posts: 4,313
    edited 2010-11-12 22:25
    If you have a serial terminal program and want an interactive capability, you could try propforth. Its like a command line, except you can also write programs. Its a little different than spin, but you can call spin programs if you need to. It also can run VGA and keyboard directly, so you can leave the rest of your rig where it is. Or you can reach it over ethernet, but you have to add a wiznet811 or a spineret.
  • RaymanRayman Posts: 14,889
    edited 2010-11-13 05:23
    John Kauffman wrote: »
    Rayman
    The Demo worked fine, much thanks. Now I can get back to coding in the backyard.
    Is there a way to make the window larger? Currently shows as about 10cm wide and 15 cm high.
    THnaks.

    John,

    Glad it worked for you! That code uses fixed sized fonts, so there are only two options for size...

    Ray
Sign In or Register to comment.