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av:dreamcastav [2019/07/27 22:29]
Link83 [Mode Selection Signals Chart]
av:dreamcastav [2019/08/27 20:45]
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-===== Dreamcast AV Connector ===== 
-The Dreamcast connector is a wild, multi-functioned beast. ​ It offers several outputs in the default configuration (Composite and S-Video), and can output two kinds of 15kHz RGB (SCART), as well as 31kHz RGB (VGA) when the proper mode is selected. 
  
-{{av:​dreamcast_av.jpg}} 
- 
-^Pin^Description^Pin^Description^ 
-|  1  | Ground ​ |  9  |Horizontal Sync (for VGA)| 
-|  2  | Right Audio  |  10  |Composite Sync| 
-|  3  | Left Audio  |  11  |S-Video Chrominance (C)| 
-|  4  | +12v  |  12  |S-Video Luminance (Y)| 
-|  5  | +5v  |  13  |Composite Video| 
-|  6  | Mode Select 1  |  14  |Blue Out | 
-|  7  | Mode Select 2  |  15  |Green Out | 
-|  8  | Vertical Sync (for VGA)  |  16  |Red Out | 
- 
-==== Usage Notes ==== 
-The mode select pins are 6 and 7.  Ground either one for two kinds of 15kHz RGB (SCART), ground both for 31kHz RGB (VGA). ​ **Note** that the Dreamcast outputs VGA, the box or cable does not '​upscan',​ so Dreamcast VGA boxes cannot be used for converting low-res RGB to VGA on other consoles. 
- 
-You should use a 220uF capacitor on each of the RGB lines (+ towards console). 
- 
-<box round warning 40% |15kHz/​31kHz RGB Note:> Most Dreamcast games are compatible with both 15kHz and 31kHz RGB modes (SCART and VGA) However a small percentage are not compatible and will show either a warning message on the Dreamcast'​s menu, or a blank screen. </​box>​ 
- 
-If a certain game will not boot in either RGB mode it can sometimes be '​forced'​ into RGB by fitting a break-before-make switch between ground and one, or both, mode select pins. Once this is done power up the Dreamcast with the switch in the '​standard mode' (Neither pin grounded) and flick the switch after the game disk has already started to be read (When loading original GD-ROM'​s you will hear a '​beep'​ sound from the drive at this point) this can often trick incompatible games into the desired mode. 
- 
-==== Mode Selection Signals Chart ==== 
-When the mode select pins are used certain signal outputs are enabled or disabled:- 
- 
-^Pin^Description^Standard '​TV'​ Mode^15kHz RGB (SCART)^31kHz RGB (VGA)^ 
-|  1  | Ground ​ | Ground | Ground | Ground | 
-|  2  | Right Audio  | Right Audio  | Right Audio  | Right Audio  | 
-|  3  | Left Audio  | Left Audio  | Left Audio  | Left Audio  | 
-|  4  | +12v  | +12v  | +12v  | +12v  | 
-|  5  | +5v  | +5v  | +5v  | +5v  | 
-|  6  | Mode Select 1  | Unused | Unused | Grounded | 
-|  7  | Mode Select 2  | Unused | Grounded | Grounded | 
-|  8  | Vertical Sync  | VSYNC | VSYNC | VSYNC | 
-|  9  | Horizontal Sync  | HSYNC | HSYNC | HSYNC | 
-| 10  | Composite Sync| ? | CSYNC | Disabled | 
-| 11  | S-Video Chroma (C)| S-Video Chroma | ? | Disabled | 
-| 12  | S-Video Luma (Y)| S-Video Luma | ? | Disabled | 
-| 13  | Composite Video| Composite Video | ? | Disabled | 
-| 14  | Blue  | Disabled | Blue | Blue | 
-| 15  | Green  | Disabled | Green | Green | 
-| 16  | Red  | Disabled | Red | Red | 
-Note:- The HSYNC and VSYNC signals on the AV port come directly from the '​Holly'​ GPU, so are likely active in all modes (Even standard '​TV'​ mode, when no RGB signals are present) CSYNC is generated by the DAC, so is unfortunately only active in specific modes. 
- 
-==== Other ==== 
-[[dreamcastRGB|Ryu'​s Dreamcast RGB mod]] \\ 
-[[http://​www.gamesx.com/​grafx/​dricas.gif|Dreamcast VGA Box Schematic]] 
- 
----- 
-See here for the [[http://​www.gamesx.com/​avpinouts/​dricas.htm|old GameSX Dreamcast pinout page]]. 
 
 av/dreamcastav.txt ยท Last modified: 2019/08/27 20:45 (external edit)
 
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