Realtime Graph on embedded system - performance problems

[bryons009]

I'm wondering what I can do to fix my problems... I will be reading data from a sensor and plotting the x/y points in realtime... I am using QWT to do this and it works fine on my development computer. The board I am developing for is the TS4700, and when I run my software on this board the performance is bad for the graph. It seems that any animation overloads the CPU? I'm not sure if this is a coding issue or something else... As long as the animation isnt visible (looking at a different tab or something) everything seems to work fine, if I show the animation, it loads up the CPU and I lose control of my mouse. If I set a timer to stop the plotting after X seconds I will regain control when it stops...

It seems just any animation kills the CPU - any ideas?

[Uwe]

Obviously you try to draw a curve with many points too often. The first thing you ( and everyone writing a similar application ) should do is to decouple sample and refresh rate using a timer.

How to improve the performance of a replot is a different story, that heavily depends on the specific details of your plot. F.e the oscilloscope example shows a tricky implementation that is able to update a curve with many, many points with almost no CPU load - try it on your board.

Uwe

[bryons009]

Thank you I will look into that example and implement your suggestion. Also to note is that I'm using qwt 5.2.1 and not 6.0.2... The example you suggest looking at isnt available in 5.2.1. Are the methods implemented still applicable with the new functions being used from 6.0.2 (or whichever version of qwt that the example comes with)?

Again, thank you for the response and for being so quick with it. I am going to try and change this and check out the oscilloscope as well.