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

Comments

• Peter Jakacki Posts: 8,787

  2016-02-07 - 03:07:26

  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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• rogloh Posts: 1,656

  2016-02-07 - 07:38:02 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]
  
  
• jmg Posts: 14,123

  2016-02-07 - 08:02:26

  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 ?
  
  
• zx81vga Posts: 53

  2016-02-10 - 18:54:21

  Hi Propeller-Friends,
  
  there is an Update
  
  Changes in v1.1
  
  VGA 256x192 BMP
  VGA 320x240 BMP
  VGA 512x384 BMP
  
  added.
  
  Greetings from Nuremberg, Germany
  
  Werner
• tonyp12 Posts: 1,950

  2016-02-10 - 20:34:29 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).
  
  
  
• zx81vga Posts: 53

  2016-02-13 - 14:56:23 edited 2017-02-08 - 15:09:52

  Hi Propeller-Friends,
  
  there is a new Update for VGA3PIN
  
  Changes in v1.2
  
  
  
  Greetings from Nuremberg, Germany
  
  Werner
  
• zx81vga Posts: 53

  2017-02-08 - 15:08:44 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
  
  
  
  Have Fun...
  
  Greetings from Nuremberg, Germany
  
  Werner
  
• Daviduk Posts: 8

  2018-03-28 - 20:40:16

  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
• zx81vga Posts: 53

  2019-10-14 - 07:14:07

  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
• Cluso99 Posts: 15,544

  2019-10-14 - 08:16:54 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
  
  

  

  

  VGA-2pin.jpg

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• zx81vga Posts: 53

  2019-10-14 - 11:36:58 edited 2019-10-14 - 11:39:11

  Hi,
  
  @Cluso99
  
  Thanks for the Info...
  
  But i must work on the ZXGame Interface by @Bean
  
  Werner