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tmshaw
05-27-2010, 10:33 AM
www.microvga.com/ (http://www.microvga.com/)

Description from that website:
"MicroVGA is low-cost Microcontroller to VGA interface providing 80x25 16 color text mode (physical resolution is 800x600 at 60 Hz). MicroVGA is connected to a MCU via 2 or 4 wire RS-232 TTL or LVCMOS compatible interface. Display is controlled using ANSI Terminal codes (such as cursor movement, colors, etc).

In addition to VGA output, the interface also provides NTSC/PAL signal output for television viewing and PS/2 keyboard input. This makes MicroVGA the ideal solution for user interface in embedded applications."

Would there be any advantage in trying to use this little "graphics card" with the a Prop board? What would be the pros and cons?
It's kind of cool that it includes a keyboard port...

I'm not sure if the prop and this card would even be compatible...

Post Edited (tmshaw) : 5/27/2010 3:41:54 AM GMT

Tubular
05-27-2010, 10:46 AM
The good news is that the prop can do all of what you mention, and still have cogs left over for other tasks. It can also do lo res graphics (didn't see that microVGA could do that on their demo page at www.microvga.com/uvga-images (http://www.microvga.com/uvga-images) ). The native res for text modes can be higher than 800x600 on the prop, too

microVga is really for other microcontrollers that don't have any video capability at all

There is also a similar product from 4dsystems.com.au with better graphics / bitmap capability

cheers
tubular

AntoineDoinel
05-27-2010, 05:12 PM
Hello

I ordered some of those modules two months ago, especially because at that time there was no proper video driver to do ANSI terminal on VGA with the propeller. But now this has changed, there's a VGA driver doing different bg/fg color per single char at 80x25.

PROS
· - It's small, well built and ready to use.
· - The price, very competitive.
· - The SEL input allow to steer the connected mcu on secondary TXD/RXD pair.
· - Has a SysReq output that can be used to trigger reset or some other function of the attached MCU (I just wired it on the setup pad to recall setup).
· - Has an SPI mode (didn't try it though).

CONS
· - The quality of the output is *BAD* compared to propeller. What you see on their website pics it's happening on any monitor I tried, it's like the bad scaling effect of the early LCD monitors, like a 640x480 badly scaled scaled up to 800x600.
· - Same as above (or worst) for the monochrome TV output... this one it's not even legible, and I tried·two LCDs and two CRTs, 7" to 32", color and B&W, but in the end I gave up on using it!
· - The serial input buffer size is limited, unless you're going to use RTS/CTS or SPI mode you can expect to lose chars if you don't rate limit the sender. So native propeller serial (e.g. PropCMD) give mangled output, ZiCOG is mostly ok because the emulation is limiting rate.
· - There's broad ANSI sequences support, but still it seems that the firmware react badly to unespected sequences (under zicog start wordstar, the screen disappear with no signal and blinking power for a few secs, then·you get two top rows of red coloured ERR! ERR! ERR! etc.)
· - The keyboard has no LED control, similar to our 1-pin keyboard driver.


So in conclusion you'd better stick with prop if you can.

And maybe the guy producing the modules should switch to prop too http://forums.parallax.com/images/smilies/yeah.gif
The module is based on a PIC24 and a CPLD, a pin compatible prop replacement could easily be made with same pinout and same (good) features, but with much better output.

Regards
Alessandro

pullmoll
05-27-2010, 08:40 PM
tmshaw said...

Would there be any advantage in trying to use this little "graphics card" with the a Prop board? What would be the pros and cons?



You can do that with the Propeller: http://forums.parallax.com/forums/default.aspx?f=25&m=451538

The disadvantage of a serial connection is, of course, speed. If you're going to transmit a colourful text image of 80x25, you may have like 2500 bytes per screen. At 115k2 baud it takes ~ 1/4 second to fill the screen. Having the VT100 (ANSI) emulation on the same Propeller and communication through a rendezvous long should be faster.

The advantage of an external solution is you don't was precious hub RAM for the frame buffer and the VT100 decoder, plus you would need 3 cogs for a "local" solution, while you need only 1 (serial IO) for the external solution.

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Pullmoll's Propeller Projects (http://pmbits.ath.cx/prop/)

HollyMinkowski
05-27-2010, 09:16 PM
The price looks good but if the video is poor like AntoineDoinel said
then it would drive me nuts! Prop video is clean http://forums.parallax.com/images/smilies/smile.gif

Rayman
05-27-2010, 10:52 PM
Nice intrinsic VGA output is the whole reason I started working with Propeller...

Personally, I think it'd be pretty crazy to buy an external VGA board for the Prop (unless, of course, it was Prop powered)!

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My Prop Info&Apps: ·http://www.rayslogic.com/propeller/propeller.htm

My Prop Products:· http://www.rayslogic.com/Propeller/Products/Products.htm

AntoineDoinel
05-28-2010, 01:18 AM
Rayman said...

Nice intrinsic VGA output is the whole reason I started working with Propeller...

Personally, I think it'd be pretty crazy to buy an external VGA board for the Prop (unless, of course, it was Prop powered)!



Agreed, that's why I called it "blasphemy" in the catalyst thread when I·confessed my little experiment http://forums.parallax.com/images/smilies/lol.gif

However to be fair, at that price I don't consider it a ripoff at all:·on VGA the jerky scaling is annoying but still well readable, and I forgot to mention one·of the·PROS, supply is +5V and there's one·onboard +3.3V regulator with output pin, it just seemed right for the RamBlade...

OK, I was lost but now I see: redemption is·wiring "the thing" to some old RCM2200 module I got somewhere, then·some·hailing of the·Almighty Prop VGA_Text 1280x1024·will restore the balance http://forums.parallax.com/images/smilies/tongue.gif