graph doesn't render in some cases

[riktw]

Hello

I got uGFX working after a while with a 32F429IDISCOVERY. I can draw 2 buttons and each button controls an LED.

I wanted to add a graph and there is why it went wrong. I eventually managed to draw a graph underneath the buttons and I can add datapoints. But if I add a variable in my main, so just "int test;" and assign it a value "test = 42;" then my graph isn't rendered anymore.

This code works: http://pastebin.com/057a2aZX and this code does not: http://pastebin.com/G0kDwLfR

The only difference is that on line 118/119 I declare a variable and assign it a value. The buttons do still work however. If I debug the code it seems that "gh = gwinGraphCreate(&g, &wii);" goes wrong and returns NULL for gh. But why a variable somewhere else causes that, no clue.

I don't use an OS and it's a st32coremx based project. So it uses the stm32f4 hal drivers and GCC as the compiler. I hope someone knows what is going on here

Best regards,

Rik

[Joel Bodenmann]

Hello and welcome to the community!

I used a diff tool to ensure that the only difference really is declaring that variable, and indeed it is.
Getting a nullpointer back from gwinXxxCreate() usually indicates insufficient heap space. However, you are using a static GGraphObject so this can't be the issue. Adding that variable doesn't do anything but increasing the stack size of the main() function. Therefore, I suspect this to be an issue with hitting the max. stack size. However, that would be a very rare case.
I assume that you did the standard debugging steps already (like doing a clean build, trying adding other variables of different sizes and so on...)?

I'd strongly recommend you to try running your uGFX application on a desktop such as Windows, Linux or Mac OS X which are all support out of the box.
If you can provide us with a full, yet minimal test case that allows us to reproduce the problem we can further investigate.