X-CUBE-AUDIO-F4 SMR Library

[Daniel Moberg]

Hi,

​

I would like to have some help understanding what the measurements that i can get from the

SoundMesauRments library provided in cube actually are. What does the calculated dB's actually relate to? What is 0dB in the scale?

My setup is a mems mic connected through i2s which are sampled an feed into the SMR library.

Kind Regards

Daniel Moberg

[Amel NASRI]

Hi @Daniel Moberg​ ,

Did you checked the UM2031 (Sound meter library software expansion for STM32Cube) to look for answers to your questions?

-Amel

[Daniel Moberg]

See answer below. (Posted answer instead of reply)

Kind Regards

Daniel Moberg

[Daniel Moberg]

Hi, Yes i have checked the UM2031.

Some more details:

I am using V1.0.5 version of the SMR library, (Version taken from the smr_glo.h)

My target is the STM32F411RET

I have dumped the PCM data from the Microphone and played it on my computer and the mic data seems fine.

When i disable the prefilter using filter none I get more reasonable output. Leading me to suspect the pre-filter.

I have tested all the pre-filters, And they do no seam to react much compared to a handhold db meter.

My setup looks like below:

smr_static_param_t params;

params.sampling_rate = 48000;

err = smr_setParam(&params, &m_smr.memory);

smr_dynamic_param_t dynamic_params;

dynamic_params.averaging_time = 1000; // ms

dynamic_params.enable = 1;

//dynamic_params.filter_type = SMR_PREFILTER_NONE;

//dynamic_params.filter_type = SMR_PREFILTER_DCREMOVE;

dynamic_params.filter_type = SMR_PREFILTER_AWEIGHTING;

//dynamic_params.filter_type = SMR_PREFILTER_CWEIGHTING;

err = smr_setConfig(&dynamic_params, &m_smr.memory);

Can you provide some code that can verify the the library?

Kind Regards

Daniel Moberg