Looking for noise filter code

Projects Programming
1

Hi Everyone

I have been searching for days now to find a Arduino audio noise filter code.

I did find lots of noise code samples but not for Arduino IDE.

I want to read audio from ADC apply the filter algorithm and output the audio with a STM32F103C8.

Where is the Arduino DSP , FIR , IIR , Lowpass filter - library samples hiding?

Thanks.

ESP32 DSP Arduino Library
2

For STM32, also look at ARM CMSIS, it has some DSP C functions as well.

3

Thanks

I downloaded the Git-hub filter library and the very first sample I try to compile give a error.I did install Filter.h with the Library Manager.

Where is this files?

#include <AH/Timing/MillisMicrosTimer.hpp>
#include <Filters/Notch.hpp>
4

The Arduino-Filters library is not available in the library manager. To install it, download the .ZIP file from GitHub and follow these instructions: https://www.arduino.cc/en/guide/libraries#toc4

If you have two libraries with "Filters.h" installed, Arduino might select the wrong one, so it's best to uninstall the other ones you might have installed.

5

Thanks.

The one example does compile now for a Nano but very weird does not compile for the STM32F103C8.

This is my error:

Arduino: 1.8.12 (Windows 10), Board: "Generic STM32F103C series, STM32F103CB (20k RAM. 128k Flash), STLink, 72Mhz (Normal), Smallest (default)"

In file included from C:\Users\mike\Documents\Arduino\libraries\Arduino-Filters-master\src/Filters/Notch.hpp:3:0,

                 from C:\Users\mike\AppData\Local\Temp\Rar$DIa15332.23396\FIRNotch\FIRNotch.ino:22:

C:\Users\mike\Documents\Arduino\libraries\Arduino-Filters-master\src/AH/STL/cmath:16:31: note: #pragma message: FMA math fix

 #pragma message("FMA math fix")

                               ^

C:\Users\mike\AppData\Local\Temp\Rar$DIa15332.23396\FIRNotch\FIRNotch.ino: In function 'void loop()':

FIRNotch:44:27: error: 'A0' was not declared in this scope

     auto raw = analogRead(A0);

                           ^

In file included from C:\Users\mike\Documents\Arduino\libraries\Arduino-Filters-master\src/Filters/Notch.hpp:4:0,

                 from C:\Users\mike\AppData\Local\Temp\Rar$DIa15332.23396\FIRNotch\FIRNotch.ino:22:

C:\Users\mike\Documents\Arduino\libraries\Arduino-Filters-master\src/Filters/FIRFilter.hpp: In instantiation of 'FIRFilter<N, T>::FIRFilter(const AH::Array<T, N>&) [with unsigned char N = 3u; T = float]':

C:\Users\mike\Documents\Arduino\libraries\Arduino-Filters-master\src/Filters/Notch.hpp:34:6:   required from 'FIRFilter<3u, T> simpleNotchFIR(double) [with T = float]'

C:\Users\mike\AppData\Local\Temp\Rar$DIa15332.23396\FIRNotch\FIRNotch.ino:39:34:   required from here

C:\Users\mike\Documents\Arduino\libraries\Arduino-Filters-master\src/Filters/FIRFilter.hpp:32:52: warning: missing initializer for member 'AH::Array<float, 3u>::data' [-Wmissing-field-initializers]

     FIRFilter(const AH::Array<T, N> &coefficients) {

                                                    ^

exit status 1
'A0' was not declared in this scope

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.
6

It looks like your board doesn't define the A0 pin number. Which STM32 core are you using?

7

Not sure what you mean by "CORE" but I use the STM32F103C8 M3 Arm Cortex generic "Bluepill" board.

Beside the A0 warnings there is also a lot of other errors.

8

You should have installed a third-party core in the Arduino IDE boards manager to be able to compile for the STM32.
I'm not an STM32 expert, but IIRC, there are basically two of these cores: one newer, official core from STMicroelectronics, and one developed by the community. The latter uses an ancient toolchain, so I highly recommend using the official STM one: GitHub - stm32duino/Arduino_Core_STM32: STM32 core support for Arduino

I just tried the Butterworth example and it compiles without issues for the STM32F103C8 using the official core.

1 Like
9

Wow...wow...wow Thanks.
If the Carma button was still on this new web page I will press it a 1000 times.
Now compiling without errors for the STM32F103C.

10

Glad to hear it works now!

It looks like you can install ARM CMSIS as a module: GitHub - stm32duino/ArduinoModule-CMSIS: CMSIS module for Arduino IDE

They have specific Filtering Functions
I'm not sure if the F103C8 has any SIMD or DSP instructions, but you might be able to squeeze a tiny bit of extra performance out of the (hand-?) optimized CMSIS filtering functions compared to the Arduino-Filters library. CMSIS also has fixed-point integer-math filters.

11

Now I got a lot of info to play with.

The new core from github does not work on my ST LINK V2 programmer, the other core I used had the STlink programmer selectable in the ide.

12

I think the ST-Link should be supported: Upload methods · stm32duino/wiki Wiki · GitHub

13

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