2021-10-10 Attempt to get a digital filter (HP 25kHz, TP 250kHz) up and running with an STM32L476G-DISCO
Theory/Guide:
https://www.youtube.com/watch?v=QRMe02kzVkA - IIR Filters - Theory and Implementation (STM32) - Phil's Lab
https://micromodeler.com/dsp/ - Online Filter Generator
https://deepbluembedded.com/stm32-dac-tutorial-example-hal-code-analog-signal-genreation/ - DAC (with triggers) tutorial
Order of operation:
- Get the ADC up and running with the Board HAL and the HAL documentation
- Get the DAC up and ...
- Copy a filter with code from the internet and check its behaviour with a spectrum analyzer
Estimated Filter-"Power"
Samling Rate [Msps - Mega samples per secound) 5.44 Msps @ 12 Bits (S.177 https://github.com/ColtanAkaEdoc/DigitalFilterWithSTM32/blob/main/Documents/Datasheet_Chip-stm32l476vg.pdf)
ENOB - Effective nuber of bits - https://www.itwissen.info/ENOB-effective-number-of-bits.html STM32LF76xx -> 10.4 Bits (S.181 https://github.com/ColtanAkaEdoc/DigitalFilterWithSTM32/blob/main/Documents/Datasheet_Chip-stm32l476vg.pdf)
Anti-Alias Filter - Dependent on sample rate (f_s) and ENOB Required attenuation reffered to gain within pass range at f_s: 6dB x ENOB