VGA with 3 Pins ***UPDATE*** VGA with 5 Pins and 8 Fore/Background-Colors

zx81vgazx81vga Posts: 53
edited 2017-02-08 - 15:16:00 in Propeller 1
Hello Propeller-Friends,

sometimes i need more Pins on the Propeller with VGA.

The Result is:

VGA3PIN 1.0

here to find

http://propeller.ws-nbg.de/main.php

Greetings from Nuremberg, Germany

Werner

Comments

  • Thanks Werner, I will try it out. Like the LCARS website, had to think for a moment to find the code. :)

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  • roglohrogloh Posts: 1,648
    edited 2016-02-07 - 07:38:26
    Hello Werner,
    If you want to save another pin, I have found some monitors will allow a composite sync signal to be used instead of separate H/V syncs (I have a couple of Sony Trinitrons that do this). Depending on your monitor support you can also resistively add the signals to combine sync and green video together resulting in a 2 wire VGA cable. Here is a snippet of a circuit I successfully used with the P1 when I was pin limited to get simultaneous composite and VGA signals generated. I was using a 1 pin composite object available from the OBEX if I recall correctly and my own two pin VGA using Sync on Green. So just 3 pins gave me my mono VGA and composite video leaving a lot of pins freed which I needed for my other buses [img][/img]

    vga.png
  • jmgjmg Posts: 14,113
    rogloh wrote: »
    Hello Werner,
    If you want to save another pin, I have found some monitors will allow a composite sync signal to be used instead of separate H/V syncs (I have a couple of Sony Trinitrons that do this).

    In another forum, the claim was that pretty much all VGA Monitors simply XOR H & V, then extract sync info.
    Could pay to test that ?

  • Hi Propeller-Friends,

    there is an Update

    Changes in v1.1

    VGA 256x192 BMP
    VGA 320x240 BMP
    VGA 512x384 BMP

    added. :smile:

    Greetings from Nuremberg, Germany

    Werner
  • tonyp12tonyp12 Posts: 1,950
    edited 2016-02-10 - 20:42:05
    Should not be to hard to create composity sync in software, but does 90% of monitors support it and should you use H-sync input for it?
    Sync compositing in the computer industry.
    As these signals are normally generated by digital logic circuits in computer systems, the composite sync signal has also commonly been produced simply by OR-ing (a)
    or exclusing-OR-ing (b) the horizontal and vertical sync signals.

    The former practice is commonly known as “block sync,” and no horizontal pulses occur during the composited vertical sync pulse.
    The XOR compositing produces serrations similar to those produced in television practice, but without preserving the falling edge position.

    Note also that, since the vertical sync in typically produced by counting horizontal sync pulses, the V. sync leading and trailing edges usually occur slightly after the H. sync leading edge; this can result in the spurious transitions shown in the composite sync output if the two are simply XORed, as in (b).

    tmp7ee1141_thumb.png
  • zx81vgazx81vga Posts: 53
    edited 2017-02-08 - 15:09:52
    Hi Propeller-Friends,

    there is a new Update for VGA3PIN :smile:

    Changes in v1.2

    vga3pin_modes.png

    Greetings from Nuremberg, Germany

    Werner
  • zx81vgazx81vga Posts: 53
    edited 2017-02-10 - 20:12:50
    Hello Propeller-Friends,

    Here is a 5 PIN Version:

    VGA5PIN 1.1 with 8 Fore/Background-Colors

    here to find

    propeller.ws-nbg.de/main.php

    vga5pin_modes.png

    Have Fun...

    Greetings from Nuremberg, Germany

    Werner
  • Werner, this is very impressive. I presume this is an improved version of what you included in the ZX81VGA project?

    How does it compare to the PropGFX?

    Thank you
  • Hello Propeller-Friends,

    Here is a 4 PIN Version:

    VGA4PIN 1.0 with 4 Fore/Background-Colors

    There are also Updates for:

    VGA3PIN 1.3 Textmode 320x240 Font 8x8, 8x12, 8x16 added.
    VGA5PIN 1.2 320x240 Font 8x12 and 320x240 Font 8x16 added.

    As allways here

    Have Fun...

    Greetings from Nuremberg, Germany

    Werner
  • Cluso99Cluso99 Posts: 15,542
    edited 2019-10-14 - 08:36:55
    A looong time ago, VS & HS was discussed using a single pin and IIRC a pair of XOR gates. Sorry, I forget who came up with the idea.

    It was based on the pin being tristate when no HS or VS, 0 for HS and 1 for VS. The output had a series 5K followed by 10K to Vcc and a series 5K followed by 10K to ground.
    The gate inputs come from each 5K-10K joint.
    Trying to recall the XOR connections

    Found it! Not quite the same, but you can get the idea :smile:

    VGA-2pin.jpg
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  • zx81vgazx81vga Posts: 53
    edited 2019-10-14 - 11:39:11
    Hi,

    @Cluso99

    Thanks for the Info...

    But i must work on the ZXGame Interface by @Bean :smile:

    Werner
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