TV_text and the spin stamp

Rob7

Gent's
I have just received my spin stamp and board of education. I have made the corrections to the spin code, but I cannot see any text ! I have a blue screen though.
I added _clkmode=xtal1+pll8
·········· _xinfreq=10_000_000
P0 resistor 1.2 k
P1 resistor 560
P2 resistor 270

Has anybody had this problem ?
I am new to spin and am trying to understand the code.

I have attached the spin code I am useing.

Paul Baker

That is just the driver, you need a top level file which directs the driver what to display, check out Examples\Library\TV_Text_Demo.spin for an example top level file for that object.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Rob7

Thanks, Paul
O.K. now I feel real stupid.
I will try that, I should have completed all of the PEK labs first ! Objects are my next chapter.
Thanks again
Rob7

W9MAS

I have the same problem with the TV Text composite signal. Most of the time I get some text but it's not right. Behaves irratic. If I reset, I sometimes get blue screen or nothing at all. I'm using an ATI HDTV card in my PC for a display.

It work's perfectly on a regular TV set!

Almost looks like an overdriven signal (>1V P-P) or something. I included a pic.

Paul Baker

It's hard to tell whats going on with the apparently blank screen you've captured.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

W9MAS

UPDATE

I read Paul Baker's reply. I downloaded the TV Text Demo and that works perfect on my Proto Board. (Note: I scratch built the circuitry to morph my Proto board into a Demo board.)

Any ideas?

W9MAS

Paul:

Disregard the image I attached.·The capture didn't·work. What I get is a really bright, washed out·text and background, other times blue or black.

Paul Baker

Im having a little difficulty following you, you have a ProtoBoard in which you built up a RCA plug and you can run TV_Text_Demo, it runs on a TV but not your TV card?

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

W9MAS

Partially correct. Been experimenting as I write. The TV Display program example from the Propeller Tutorial Chapter 3 gives the results I described in my first message. On a regular TV it works fine.

The TV Text Demo works fine on composite inputs to a regular TV and my ATI PC TV card.

W9MAS

By the way, I am new to the Prop products and am very impressed with the VGA display quality. Really fantastic!

Paul Baker

I dont know which code you are refering to, which tutorial?

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

W9MAS

Paul,

I'm following the The WebPM-v1.01.pdf book. Chapter 3.· See pic.

Thanks for the help!

W9MAS

Oops. . .The correct name of the application is Display.Spin, located in the Prop Tool program folder.

Paul Baker

Gotcha, I cant look at the output until Im back at work. Im thinking that there are some supersaturated colors being used and the TV card is freaking out because of it. Try running the Graphics_Palette.spin in Examples/Library, and tell me if you get similiar "freaking out" on the top of the display.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

W9MAS

Yep, that's kind of what I suspect. Since it's B & W text, the peak to peak signal voltage could be overdriving the TV card composite input. Anyhow, many thanks and appreciate the help! Will try your suggestion and let ya know.

Paul Baker

Yeah, the high contrast can cause ghosting and other issues even on regular TVs, but TV cards are more susceptable to it.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Rob7

Paul,
Not to get off the subject with W9MAS, I got it working ! Great job. Thanks for the help.
W9MAS, hope you get yours working.
I attached the code for the Spin stamp, TV terminal and TV text.
Rob7

Post Edited (Rob7) : 6/12/2007 6:30:04 AM GMT

Rob7

For the newbie's like me. I attached the GraphicsDemoSpinStamp code here. Attach your RCA jack to resistors starting at
pin 0 1.2k
pin 1 560
pin 2 270
Have fun !
Rob7

Kaio

Why did you not use the original pins (12 - 14) used on Demo board? Then you would not have to change the code of the TV driver. And you could be using the SD-card driver also unchanged.

W9MAS

Paul:

The Graphics_Pallette and Graphics_Demo produce the same negative results. Through experimentation, I can get a better display by varying the resistor value on pin 12 to something lower.

Rob7

Good question ?
I need to play with the program and learn how it works, then make it simple. To a newbie, simple is best. I am still learning how spin code works.
Rob7

Paul Baker

W9MAS said...

Paul:

The Graphics_Pallette and Graphics_Demo produce the same negative results. Through experimentation, I can get a better display by varying the resistor value on pin 12 to something lower.

This probably means that the signal is over driven, or there is an impedance mismatch causing an overshoot of the voltage. As you've noticed reducing the values will help.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

W9MAS

Problem resolved.

Substitued trimmers for resistor network and adjusted for best picture quality. TV PC card is much more sensitive to variations in sync pulse amplitude than conventional television.