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jjl
Joined: 24 Feb 2011
Posts: 2
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 Posted: Fri Feb 20, 2015 2:44 pm Post subject: Understanding FT800 |
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Hi All.
I have a question regarding the operation / use of the FTDI FT800 chip / display.
I have the VM800C35A-D.
Let's say I draw a X- and an Y axis on the display. I will then sample some data and display them as dots in realtime.
Do I then have to send the hole command-list agian, including the XY-axis and the dots, so if I have 100 samples I have to send a command-list with more than 100 commands ????
Or another exampel: You have a screen with lots of buttons and you want one of them to blink, do I then again have to send all the commands for all the buttons ?
I hope I have misunderstood something 
Have a nice weekend.
Jens
Denmark
(BASCOM-AVR version : 2.0.7.8 ) |
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PeterM
Joined: 09 Jun 2008
Posts: 118
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| Posted: Fri Feb 20, 2015 8:32 pm Post subject: |
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Jens
Before I answer don't be overwhelmed by the amount of work needed to display
data or any Graphics because its not as bad as you think. You have to do things
in a slightly different way because you are now dealing with a Graphics Processing Unit
which has a lot of flexibility and power.
| Quote: | | Do I then have to send the hole command-list agian, including the XY-axis and the dots, so if I have 100 samples I have to send a command-list with more than 100 commands ???? |
Don't make it sound that bad  , yes you have to send everything again but you
already did that in the first place by drawing the screen, sampling the data and displaying
the plots, so just repeat that process again.
| Quote: | | You have a screen with lots of buttons and you want one of them to blink, do I then again have to send all the commands for all the buttons ? |
Again, yes you have to draw everything, you just repeat the routine again with any changes needed.
Don't forget all the Graphic drawing can happen really fast (typically up to 60Hz).
If you have to erase something on the LCD you don't need to erase that area, just draw
the new graphics as needed.
Note: If you don't like that method there is a demo file called plot.bas which uses a different method of displaying data
which you can also look at.
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Peter |
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PeterM
Joined: 09 Jun 2008
Posts: 118
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| Posted: Fri Feb 20, 2015 8:38 pm Post subject: |
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Jens
Before I answer don't be overwhelmed by the amount of work needed to display
data or any Graphics because its not as bad as you think. You have to do things
in a slightly different way because you are now dealing with a Graphics Processing Unit
which has a lot of flexibility and power.
| Quote: | | Do I then have to send the hole command-list agian, including the XY-axis and the dots, so if I have 100 samples I have to send a command-list with more than 100 commands ???? |
Don't make it sound that bad , yes you have to send everything again but you
already did that in the first place by drawing the screen, sampling the data and displaying
the plots, so just repeat that process again.
| Quote: | | You have a screen with lots of buttons and you want one of them to blink, do I then again have to send all the commands for all the buttons ? |
Again, yes you have to draw everything, you just repeat the routine again with any changes needed.
Don't forget all the Graphic drawing can happen really fast (typically up to 60Hz).
If you have to erase something on the LCD you don't need to erase that area, just draw
the new graphics as needed.
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Peter |
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jjl
Joined: 24 Feb 2011
Posts: 2
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| Posted: Sat Feb 21, 2015 10:19 am Post subject: |
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Hi Peter.
Thank you for your reply.
Maybe I was a bit negative 
You are right, it's another way to control a display, one have to get used to it.
I can see all the good things, few wires, easy button control, simpel touch control with the Tag command, no need for a PC and memory Card for programming the display etc. these Things was the reason for me to try the FT800.
Now I know that I have to send the hole list every time I make a change.
The Scissor command looks interesting. Can I write to the "Scissor area" without disturbing the surounding area ? Or is that just a dream ? 
Have a nice weekend
/JJ
Denmark
10.15 AM
5 deg. C. Cloudy and foggy. No Wind. |
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PeterM
Joined: 09 Jun 2008
Posts: 118
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| Posted: Wed Feb 25, 2015 1:37 am Post subject: |
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jjl
| Quote: | | The Scissor command looks interesting. Can I write to the "Scissor area" without disturbing the surounding area ? Or is that just a dream ? |
I am no Graphics Expert but looking at various samples to get an understanding, it looks like you can
clip around the area and just draw within the selected coordinates you specify. The Scissor works just like a Scissor I suppose.
I another similar function to look at is StencilOp.
Note:
Just for anyone reading this post, to use the FT800 is straight forward BUT to benefit using
some of the advance Graphics functions an understanding of OpenGL is a must.
The FTDI/FT800 doco is not very descriptive because they assume you have some Graphics
background like OpenGl.
Another great source of samples is in this PDF by the FT800 God - James Bowman
http://excamera.com/files/gd2book_v0.pdf
Also have a look at his mindblowing demos!
http://excamera.com/sphinx/gameduino2/
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Peter |
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