Prop TV Output timing and specs
DogP
Posts: 168
Hey,
I've been working on making the Prop a display device for a project I'm working on, but after messing with it for a while, I'm not sure it'll work as well as I hoped. So I'm looking to change my focus to using an FPGA, but the thing that made the Prop especially useful was the ability to output to a TV. I know I can use the same circuit as the Prop for generating TV output (3 outputs w/ resistors), but I'm having a hard time finding documentation for the signals. Is there anywhere that explains where, why, and what bits are output from the Prop (maybe some pseudo-code for what's happening)? I've found some good examples of B/W, but documentation on color is pretty limited, and most use a seperate IC (usually the AD724) to generate the NTSC signal from RGB. I'm very interested in how the Prop does it since it does it so well and without any extra ICs.
Here are a few of the sites I've come across:
www.rickard.gunee.com/projects/video/sx/howto.php (Best one on color, but explains more about why instead of how to do it)
excamera.com/articles/15/ntsc.html (B/W implemented in an FPGA)
instruct1.cit.cornell.edu/courses/ee476/FinalProjects/s2002/carlo/index.html (uses extra hardware)
And I've tried looking through TV.spin, but that's kinda hard to read, and there's things like waitvid which are controlled internally.
I figured I'd try posting here since the Prop does exactly what I'm wanting, just the memory size and transfer requirements (and my wants) are a little above what I can do on the Prop. Thanks,
Pat
I've been working on making the Prop a display device for a project I'm working on, but after messing with it for a while, I'm not sure it'll work as well as I hoped. So I'm looking to change my focus to using an FPGA, but the thing that made the Prop especially useful was the ability to output to a TV. I know I can use the same circuit as the Prop for generating TV output (3 outputs w/ resistors), but I'm having a hard time finding documentation for the signals. Is there anywhere that explains where, why, and what bits are output from the Prop (maybe some pseudo-code for what's happening)? I've found some good examples of B/W, but documentation on color is pretty limited, and most use a seperate IC (usually the AD724) to generate the NTSC signal from RGB. I'm very interested in how the Prop does it since it does it so well and without any extra ICs.
Here are a few of the sites I've come across:
www.rickard.gunee.com/projects/video/sx/howto.php (Best one on color, but explains more about why instead of how to do it)
excamera.com/articles/15/ntsc.html (B/W implemented in an FPGA)
instruct1.cit.cornell.edu/courses/ee476/FinalProjects/s2002/carlo/index.html (uses extra hardware)
And I've tried looking through TV.spin, but that's kinda hard to read, and there's things like waitvid which are controlled internally.
I figured I'd try posting here since the Prop does exactly what I'm wanting, just the memory size and transfer requirements (and my wants) are a little above what I can do on the Prop. Thanks,
Pat
Comments
That's probably the best you'll do until the second application note (on the video generator this time) gets done.
The main constraint is memory! Everything depends on the software driver.
Post Edited (deSilva) : 8/15/2007 11:51:54 PM GMT
found in this thread: http://forums.parallax.com/showthread.php?p=577138.
There is also an early thread with information about the color modulation, but I don't find it...
Cheers
Andy
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E3 = Thought
http://folding.stanford.edu/·- Donating some CPU/GPU downtime just might lead to a cure for cancer! My team stats.
deSilva: That looks exactly like what I'm looking for... basically, I'd like to know which bits need to be signaled at what time to create the desired output. The Parallax guys made it too easy for us by creating a driver to handle the timing and control of the outputs [noparse];)[/noparse] . And yeah, for my project I'm basically needing a large framebuffer to pump data through at high speeds, and the prop just doesn't quite have the resources for it. Possibly the Prop 2 will help when it arrives, but for the time being I wouldn't mind trying it out with the Spartan 3E eval board I've got (lots of speed, memory, and can be totally customized for my application).
Please let me know when you've got the info available, and if anyone else has any info and/or links, I'd appreciate it. Thanks,
Pat
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Paul Baker
Propeller Applications Engineer
Parallax, Inc.
lines 1 - 3 equalizing pulses - 2.3uS @ -40IRE, 29.477uS @ 0IRE, 2.3uS @ -40IRE, 29.4777uS @ 0IRE
lines 4 - 6 serration pulses - 27.077uS @ -40IRE, 4.7uS @ 0IRE, 27.077uS @ -40IRE, 4.7uS @ 0IRE
lines 7 - 9 equalizing pulses - 2.3uS @ -40IRE, 29.477uS @ 0IRE, 2.3uS @ -40IRE, 29.4777uS @ 0IRE
lines 10-21 blank - 4.7uS @ -40IRE, 0.6uS @ 0IRE, 9 cycles 3.579545MHz colorburst @+/- 20IRE, 55.740uS @ 0IRE
lines 22-262 active video - 4.7uS @ -40IRE, 0.6uS @ 0IRE, 9 cycles 3.579545MHz colorburst @+/- 20IRE, 1.385uS @0IRE, 52.855uS active video, 1.5uS @ 0IRE
rising colorburst on even lines, falling colorburst on odd lines
Note: TVs are quite tolerant of timing variations except for colorburst.
I also dropped by the Hydra forum and noticed this post: http://forums.parallax.com/forums/default.aspx?f=33&m=187877 ... so that may be helpful too.
Thanks,
Pat
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Paul Baker
Propeller Applications Engineer
Parallax, Inc.
Pat