Arduino for STM32

There is a lot of settings in the STlink Utility app - Option Bytes atc.
Doublecheck whether there is not something set such it is disturbing..

Below is a simulation of the input circuitry and Sample and Hold of STM32F103 ADC. Radc is 1k and Cadc is 8pF (Datasheet). C1 is a parasitic capacity of the input pin and wiring. Diodes and 200ohm resistor -> simplified PIN protection wiring inside the chip. 1. First picture is how the edges look li...

Even with 0ohm source the is an internal Radc and sampling capacitor Cadc.
Radc is usualy 1k-10k and Cadc 5-15pF (doublecheck the DS).
That limits the sampling rate, as you have to fully charge the Cadc via Rsource+Radc between the samples within the ADC input voltage limits.

This is provided by ARM: https://github.com/ARM-software/CMSIS_5/tree/5.5.1/CMSIS/DSP/Lib/GCC Damm ... ".a" files ==> Compiled libraries No source .. Well i'd prob not understand the "magic" anyway /Bingo https://github.com/ARM-software/CMSIS_5/tree/5.5.1/CMSIS/DSP/Source

Look at my above link - I did CMSIS FFT on 407, you may download sources of libraries for DSP and other math with FPU. https://www.st.com/content/st_com/en/products/embedded-software/mcu-mpu-embedded-software/stm32-embedded-software/stm32-standard-peripheral-libraries/stsw-stm32065.html#get-software...

Another argument for -Os is when you start experiments with those hw switches. With higher optimisation you may lose track.

A rather long thread on how we messed with stm32F407 FPU in 2017 https://web.archive.org/web/20170715084304/http://stm32duino.com/viewtopic.php?f=39&t=2001&sid=6ae2281d3c685a20709d7fc23d399868 There are some gcc settings recommended, like -mfloat-abi=hard -mfpu=fpv4-sp-d16 -fsingle-precision...

Hmm, most realistic results are with -Os, imho. With -2, -3, you are getting results which are off my understanding :) They indicate you have to be pretty careful with compilers because of optimization. Therefore Fortran is the only lanuage "approved" for whetstone, they say. Why to optimi...

Some reading on D and W
http://users.ece.utexas.edu/~ljohn/teac ... eicker.pdf

I would recommend to stay with -Os, as the higher levels may produce questionable results.

@ag123: let us stay with dhrystone and whetstone in this thread..