Which object and method do we use to display via Composite video output ?
OzStamp
Posts: 377
Hi fellow Proppers..
Just finishing off·a project .
Need to display 3 decimal values and some other data on a screen.
Planning to buy a LCD TV screen ( cheap these day's) for the customer and install this
so they can see the necessarry data from a 5 or 6M distance.
Initially to get going want 3 or so static bits of text .. see sample below.
Behind these permanently displayed text strings we wish to display 3 variables..
these variables are updated fairly rapidly ... via 3 separate cogs feeding the display..
·· static text···················· dynamic text
···
Speed of motor 1··· >>·· ( the var SPEED1 here)
Speed of motor 2··· >>·· ( the var SPEED2 here)
speed of motor 3··· >>··· ( the var SPEED3 here)
We have a composite video signal from the Prop controller card so we cannot or want to
use a VGA object...we are not displaying fancy graphics just text..( large characters.. scaleable)
Presenly got something going but the screen flicker looks really silly...
Have looked at lots of samples and a little lost which one to use.
Will share the final outcome of it all here for sure.
CHeers··· Ron Melbourne OZ
Post Edited (OzStamp) : 1/2/2008 3:52:05 AM GMT
Just finishing off·a project .
Need to display 3 decimal values and some other data on a screen.
Planning to buy a LCD TV screen ( cheap these day's) for the customer and install this
so they can see the necessarry data from a 5 or 6M distance.
Initially to get going want 3 or so static bits of text .. see sample below.
Behind these permanently displayed text strings we wish to display 3 variables..
these variables are updated fairly rapidly ... via 3 separate cogs feeding the display..
·· static text···················· dynamic text
···
Speed of motor 1··· >>·· ( the var SPEED1 here)
Speed of motor 2··· >>·· ( the var SPEED2 here)
speed of motor 3··· >>··· ( the var SPEED3 here)
We have a composite video signal from the Prop controller card so we cannot or want to
use a VGA object...we are not displaying fancy graphics just text..( large characters.. scaleable)
Presenly got something going but the screen flicker looks really silly...
Have looked at lots of samples and a little lost which one to use.
Will share the final outcome of it all here for sure.
CHeers··· Ron Melbourne OZ
Post Edited (OzStamp) : 1/2/2008 3:52:05 AM GMT
Comments
The tv_text / tv driver should be able to draw larger characters. It's normally set up for 40 x 13, but uses a horizontal scaling factor of 4. If you reduced that to 2, you should get a 20 x 13 screen with larger characters. If you also switched to using the full 16 x 32 ROM font with two tiles per character, that should reduce things vertically to 20 x 6 or 20 x 7 which would give you the sort of display size you want.
Thanks for the great suggestions.
Will investigate that TV text object and implement something .
Happy New Year to you both..
Cheers Ron Nollet Melbourne OZ..
Perhaps the simplest way is to get text on a TV is to use the TV Text object at http://obex.parallax.com/objects/67/. But as depending on how much data and how often it needs to be updated you may get flickering as there is no display buffer. You mention flickering so you may have already experienced this.
Alternatively, use the Graphics object at http://obex.parallax.com/objects/55/. Unzip the download and start with Graphics_Demo.spin to see how things work. Graphics is double buffered so flicker is gone. The text characters are scalable if memory serves. However this approach uses a lot of memory, so if your application is big you may run out. You can comment-out many lines in the Graphics_Demo.spin and other dependent files to reduce the memory footprint though.
Good Luck, David
Just looking into it right now... re the TV Text object..as per the above suggestions by Mike and RJO
If the screen flickers while updating the variables .. it will not be of use to me..
I have plenty of code space left..
Screen update is as fast as possible.. as we are monitoring speed ( from pulse encoders) and also
3 absolute SSI encoders which return absolute angle position on a 3 axis measuring arm..
Cheers Ron Melbourne OZ
Another thing came to mind... Awhile back I too had flicker issues with TV Text. Then I went to Graphics, and I remember that wasn't exactly a satisfying solution either as it didn't fill the screen, and I ran out of memory. You might run into the same issues.
If-so, you might want to consider a hardware solution. Look here: www.hittconsulting.com/products/sxvideomodule/ at Bean's nice little SX powered video display module. It can do 6 lines of text each with up to 16 characters, costs $34 USD, NTSC/PAL capable and even makes sound too.
Given the follow up description of your application - sounds to me like you're going to at least need the graphics approach instead of TV Text - or the video display module mentioned above.
Regards,
David - Jakarta
it is a matter of half an hour to make you a flicker free large screen display. It will take much longer to explain what to know for it and what to do.
Please give me some more specifications than in your first posting.
Maybe you first can try my MPE_TEXT I posted months ago for a large display
http://forums.parallax.com/attachment.php?attachmentid=49490
40x24, 16 color, multiple font support.
OBC
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In this post http://forums.parallax.com/showthread.php?p=682130 you mention the existence of MPE_TEXT_013.SPIN. Is there any significant change from the 013 to the 012 version you link to in today's?
The first availability of the 012 version I can find when searching is in this post: http://forums.parallax.com/showthread.php?p=677592
Thanks - David
Woow I am overwhelmed by the response from you all.
I have just had a go with the Tv Text object and that seems to do what we need.
Just need to digest how to postion the cursor on the screen and overwrite the 'Dynamic variables)
have also downloaded your object "DeSilva" thnx for that.
Have a look at this link DeSilva you can see what we would like to do.
You can see he has (Paul Hubner) many Static text and also lots of Dynamic variables..
I looked at that post 2 weeks ago.. just prior to going away for a summer break ( yes it summer here)
My respones there to Paul Hubner is me (XRHONDA)
Cheers Ron Melbourne OZ
David, I don't now
Post Edited (deSilva) : 1/2/2008 5:16:12 AM GMT
I am starting to understand the TV Text object now and will look at yours also and use whatever I can
that you have already done.. thanks
So much too learn and soo little time...
Ron
Post Edited (deSilva) : 1/2/2008 5:22:50 AM GMT
I prefer to have a go myself so that I can learn how to do it ...
You have provided all i need .. I just need to massage it now to satisfy my exact needs..
Its better for me to dive into it instead of having somebody do it .. (47 year old student learning spin/asm for Prop)
Have been able to position text already anywhere I like .. so all is looking really cool..no flicker at all..just an updating
variable ... really very happy with that.
Your offer is appreciated and if I do run into trouble will ask for further help ..
Vielen Dank
cheers Ron Melbourne OZ
Glad we asked some questions.. learned alot today..
Again thnx to all that replied..
Managed to get a trial screen on the little Parallax LCD ·up and running.
See picture attached the hi-lited text is static...
Will consult with the customer re the final lcd screen and will have to adjust the
size of the characters etc etc ... all is under control..
The TV text object is ideal for what we needed.. flickerless display.. no problems at all Dave (Indonesia)
It is just a matter of positioning the cursor and writing the text..
We just plugged some variables into loops and she is up and running like a charm.
cheers
Ron Mel OZ
there are two possibilities (for a 320x240) screen.
(a) You parametrize the (original) TV_TEXT to "blow up" the pixels, but use the interlace mode.
(b) You use MPE_TEXT (non-interlaced) mode
It is not obvious to me what you finally have done.. (b) should provide higher quality, the improvement however is very dependent on the monitor. I do not remember why exactly I discarded solution (a) and turnd to (b) ...
Initially I have used the std Tv.text object.. untill we have a decision as to which monitor we will use that
will do for now..
cheers Ron
Do give deSilva's MPE_TEXT_013.spin a try. The 20X7 non-interlaced mode might be good for your application and it looks great on-screen - even in PAL with a standard 5MHz crystal at 80MHz clock.
Regards,
David
I now have a monitor so can start having a proper play.
Thnx for that suggestions will try it later today and will keep you posted.
Rgds
Ron Nollet