LPC55S69 FPU multiplication error (Hard floats)

[v_canoz]

Hello,

I have a very surprising problem with LPC55S69. The hard ABI is enabled.

float a = 255.0;
float b = 1.0;
float res = a * b;

With this simple test case I get different results each time the function is called : 

res = 0.407566
res = 0.489081
res = 0.505314

...

 What can cause this?

[v_canoz · Accepted solution]

Hi,

Further testing showed that it's due to a stack corruption. Don't know why yet, but now I'm confident it is not related to the FPU.
Sorry for disturbing!

[converse]

Can you post the whole project that reproduces this?