Realtime video

[RUBiksCUbe]

I have seen web sites that provide info on video being generated in realtime by PICs, but the only code they have as an example is in assembly. Honestly, I can't stand looking at assembly. Has anyone tried to generate video with picbasic before? I'm going to try to convert the assembly code to picbasic.

[mytekcontrols]

Sorry to say it wont work. Even in assembly with a 40 Mhz PIC it is quite a challenge (although not impossible) to generate decent video resolution. You have to bear in mind that a given horizontal scanline only lasts for about 64 microseconds. On a PIC being clocked at 40 Mhz, even the simplest assembly language instruction (NOP) will take 100 nanoseconds to complete. At first it seems fast, but you need to do more then a NOP instruction to actually display anything of value. When you start looking at shifting out information from memory, and being able to do any of the other housekeeping tasks required, it doesn't take long before you simply run out of time, and your resolution begins to suffer drastically.

Here is a very good website on what is really required:http://www.rickard.gunee.com/project.../pic/howto.php. I would suggest checking it out.

Good luck

[Luciano]

Tetris using a PIC16F84 running @ 12MHz:
(NTSC video signal).
http://www.web-ee.com/Schematics/PIC.../PICTetris.htm

[RUBiksCUbe]

I was afraid that PicBasic would be too high level of a language to work. I guess Ill attempt to learn some assembly. Uhg.

[mister_e]

it's not impossible in PICBasic but it will depend of what kind of video signal you want to generate.

Sure the assembly method will provide a better range of possibility if you want a decent/great 'resolution'. Timing issue??? Hard to create Delay? Learn how to use internal Timer or learn or to work with MPLAB stopwatch and assembly loop.

A previous thread => Assembler for dummies => http://www.picbasic.co.uk/forum/show...ssembler+blink

12Mhz, 20Mhz work great for me for OSD... but plain text with plain lines... no 3D and ... of course no colours

The Michael link is a great start point. Maybe you can find out few example on www.epanorama.net

good luck.

[mytekcontrols]

Yes I stand corrected (but only slightly ). You probably can generate video on a PIC and programmed in PicBasic, but I guarantee you it will still be quite a challenge taking this approach. And depending on your needs (which we know very little about), it still might not produce acceptable results. If you are just looking at producing a small number of units with this capability, then I would suggest using something like a BOB3 video board from these guys: http://www.decadenet.com/. Or for something even simpler (and much cheaper) may I suggest the SV1000 chip from: http://www.speechchips.com/shop/item.asp?itemid=7. Of course the BOB3 is much more capable, has 8 color text, hardware scrolling, and video overlay. But it will cost you to get these features.

If you do decide to roll-your-own, I would also suggest doing all the video generation with a separate PIC that communicates with another that runs your main code. This really would be the best approach (and similar to using your PIC with one of the above mentioned products), unless your needs are fairly simple.

Cheers,