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printf double precision but getting just single precision

Question asked by Gahlen Feld on Jun 13, 2017
Latest reply on Jun 14, 2017 by Clive One

Hello,

 

I am working on a firmware for the STM32F765.
This MCU was chosen because of its double precision floating point capabilities.
I manged to configure the FPU/Compiler (ARM GCC 5.4) to genertate correct DP native assembly instructions.
When debugging, I can verify correct DP calculations.

 

The only thing I cannot manage is to printf results in double precision.
I have tried the formatters %f and %lf but on every printf only single precision is printed out (correctly rounded results but with too less digits).
I am using newlib speed optimized (NOT nano), but also the lib stdc++ does the same.
Has somebody ever seen the printf output in double precision for an embedded ARM Cortex-M7 code with GCC & if yes, how do I get it running ?

 

Thank you in advance,
Gahlen

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