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bazi
05-21-2010, 03:54 PM
Hi,

some time ago i've made a propeller board and a programmer with some leds and buttons. But now i want to get started with TV-output.
I had a look at the example in the propeller tool, but i'm wondering how to use it.
If i open the file i'm able to view the info etc. and i see, there's a pointer on an array.

But how do i set up such an array and start the tv-application?

I hope anyone of you will help me :)

TonyWaite
05-21-2010, 05:00 PM
Hi Bazi,

I would run with a standard Parallax board with TV out, run the demo programs and then experiment
from there. It's always easiest working from a known, working base.

Regards,

T o n y

MagIO2
05-21-2010, 06:13 PM
Most drivers do have a demo-program. Most time based on the demo-board setup. So, if you use the same pins as the demo-board does, you can run this stuff right away and see how it works.

Any driver should have a comment section which describes how to use it and if it's a driver for special hardware it also includes a description on how to attach that hardware.

Also helpful is the possibility to show only the function-names for a spin-file in the propeller tool. As all PUB functions might be of interest when you use a driver in your own program.

bazi
05-21-2010, 08:29 PM
[quote]Most time based on the demo-board setup. So, if you use the same pins as the demo-board does, you can run this stuff right away and see how it works.
Actually i don't have a setup for my propeller. Its a base-board with a voltage regulator, eeprom and max3232. All other pins are available on my breadboard.
Now i would make a real PCB. I've searched for circuits along the web and could'nt find schematics of the hydra board, can anyone tell me more about the circuit propeller<->tv-out?

Another question, i have no 5mhz crystal anymore, but i will go buy one. If the store hasn't one, would a 4...8mhz crystal do the same job?
Is a 5mhz crystal required for all those example codes in spin/asm or would any other work also?

Ariba
05-21-2010, 08:46 PM
You find the demo board schematic in the PropTool's Help menu.

This is the relevant part of the TV output. You normally don't need the 4th resistor at P15, so I don't show it here.
http://forums.parallax.com/attachment.php?attachmentid=70526

The 3 resistors forms a 3 bit DAC, you can also use slightly different values (220, 470 and 1k i.e.).
Connect this TV output to a Video input and start one of the Spin demos: TV_Text_Demo.spin, Graphics_Demo.spin or Graphics_Palette.spin. You will find theme in the Example/Library directory.

You can connect the resistors also at P0..2, P4..6, P8..11, P16..18 or P24..26, but then you need to change the Basepin at start of the drivers in the Demos.

Hope this helps...
Andy

bazi
05-22-2010, 05:56 PM
Thanks for your help, it works!

But theres a question left...

Somebody said...

Another question, i have no 5mhz crystal anymore, but i will go buy one. If the store hasn't one, would a 4...8mhz crystal do the same job?
Is a 5mhz crystal required for all those example codes in spin/asm or would any other work also?

Post Edited (bazi) : 5/22/2010 11:03:47 AM GMT

Ariba
05-22-2010, 07:25 PM
For other crystal frequencies than 5 MHz you need to change the line: _xinfreq = 5_000_000
in the Demo code to the value of your crystal.
For 4..6 Mhz this should work, for higher values you need to set the PLL to 8x instad of 16x to not exeed the max. Clock freq.

Some TV drivers may have a minimal clock frequency requierement, so you must try if lower frequencies work.

Andy

bazi
05-23-2010, 03:06 AM
Ok tanks :)

I know, i'm terrible, but i can't find much about clock sources on propeller in the datasheet, ..., ...
Would it work if i connect a 20Mhz crystal and set the PLL to 4x? What is the highest possible crystal freqency?

MagIO2
05-23-2010, 04:08 AM
No, the PLL only works with a max. input frequency of 10MHz - that's somewhere hidden in the datasheet. There is a chance to overclock and use a slightly faster crystal, but definitely not a 100% faster one ;o)
What you can do is use the 20MHz without PLL, but then you run the propeller at 1/4 of the possible speed. And as already stated a TV driver requires a minimum frequency, you have to test if 20MHz is enough.

bazi
05-23-2010, 04:14 AM
20mhz is way too slow for TV and a serial line, and i have a 5mhz crystal connected.

I only wanted to know this. THANKS!