Display timing: Difference between revisions
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=Pixel dimensions= | |||
* NTSC: 384 * 264 pixels. | |||
* PAL: 384 * 312 pixels. | |||
See [[frame size]] for the '''active''' display size. | |||
=Sync= | |||
'''mclk''' refers to the 24MHz master [[clock]]. A pixel lasts 4 mclk. | |||
Notes: After /RESET goes high, SYNC goes high after 1399 mclk. | |||
[[File:Sync_timing.png|1024px]] | |||
{{Sig|CHBL|CHBL}} is the horizontal blanking signal, it tells {{Chipname|NEO-B1}} to output color 0 of [[palettes|palette]] 0, which is the [[palettes|reference color]]. | |||
{{Sig|BNKB|BNKB}} is the vertical blanking signal, it forces the [[video DAC]] inputs to 0. | |||
== Horizontal | ==Horizontal== | ||
[[File:Timing_video_lines.png]] | [[File:Timing_video_lines.png]] | ||
[[File:Timing_video_hblank.png]] | [[File:Timing_video_hblank.png]] | ||
*112 mclks (28px) | * 112 mclks (28px) horizontal sync pulse | ||
*112 mclks (28px) back porch | * 112 mclks (28px) back porch | ||
*1280 mclks (320px) active display | * 1280 mclks (320px) active display | ||
*32 mclks (8px) front porch | * 32 mclks (8px) front porch | ||
* 32 + 112 + 112 = 256 mclks (64px) horizontal blanking | |||
* 32 + 112 + 112 + 1280 = 1536 mclks (384px) total per scanline | |||
[[File:Timing_video_vblank.png]] | [[File:Timing_video_vblank.png]] | ||
| Line 29: | Line 35: | ||
BNKB (blanking to 0V) changes state 14px after H-sync (middle of the back porch) | BNKB (blanking to 0V) changes state 14px after H-sync (middle of the back porch) | ||
==Vertical | ==Vertical== | ||
Corrected from and added on from mvstech.txt (by Charles MacDonald). | |||
There are 264 scanlines per frame: | There are 264 scanlines per frame: | ||
* 8 scanlines vertical sync pulse | |||
* 16 scanlines top border (active in PAL, blanked in NTSC) | |||
* 224 scanlines active display | |||
* 16 scanlines bottom border (active in PAL, blanked in NTSC) | |||
* | Upper 9 bits of register {{Reg|REG_LSPCMODE}}: | ||
* | * $0F8~$0FF : Vertical sync (8px) | ||
* | * $100~$10F : Top border (16px) | ||
* | * $110~$1EF : Active display (224px) | ||
* $1F0~$1FF : Bottom border (16px) | |||
=Frame timing= | |||
See [[framerate]]. | |||
[[Category:Video system]] | [[Category:Video system]] | ||
Latest revision as of 12:59, 6 February 2018
Pixel dimensions
- NTSC: 384 * 264 pixels.
- PAL: 384 * 312 pixels.
See frame size for the active display size.
Sync
mclk refers to the 24MHz master clock. A pixel lasts 4 mclk.
Notes: After /RESET goes high, SYNC goes high after 1399 mclk.
CHBL is the horizontal blanking signal, it tells NEO-B1 to output color 0 of palette 0, which is the reference color.
BNKB is the vertical blanking signal, it forces the video DAC inputs to 0.
Horizontal
- 112 mclks (28px) horizontal sync pulse
- 112 mclks (28px) back porch
- 1280 mclks (320px) active display
- 32 mclks (8px) front porch
- 32 + 112 + 112 = 256 mclks (64px) horizontal blanking
- 32 + 112 + 112 + 1280 = 1536 mclks (384px) total per scanline
BNKB (blanking to 0V) changes state 14px after H-sync (middle of the back porch)
Vertical
Corrected from and added on from mvstech.txt (by Charles MacDonald).
There are 264 scanlines per frame:
- 8 scanlines vertical sync pulse
- 16 scanlines top border (active in PAL, blanked in NTSC)
- 224 scanlines active display
- 16 scanlines bottom border (active in PAL, blanked in NTSC)
Upper 9 bits of register REG_LSPCMODE:
- $0F8~$0FF : Vertical sync (8px)
- $100~$10F : Top border (16px)
- $110~$1EF : Active display (224px)
- $1F0~$1FF : Bottom border (16px)
Frame timing
See framerate.