How to use the nRF5340 DSP

[soeta]

Hello.
I am running the nRF5340 Audio sample application on the nRF5340 Audio DK.
I would like to apply a filter to the sound source using the nRF5340 internal DSP.
Please tell me how to apply the DSP.
Also, please tell me how to program the DSP.

Best regards,
kazuma

[Naeem Maroof]

Hello,

Thank you for contacting DevZone at NordicSemi.

I guess you can use CMSIS-DSP library. Please have a look at the information in this case where my colleague describes how to use this library and other resource pointers.

You can also explore the functions defined in arm_math and other include files.

Here is also an example of filtering using CMSIS-DSP library: ARM_FIR_Example

Regards,

Naeem

[soeta]

I have a general understanding of how to use DSP.
However, I am having trouble with data type conversion for using DSP functions.
The situation is described below.
--------------------------------------------------------------------
I am getting sound data in uint32_t type from I2S I/F and storing it in FIFO.
The data is transferred from the FIFO to char pcm_raw_data[FRAME_SIZE_BYTES] in encoder_thread().
The aforementioned pcm_raw_data was deemed appropriate to apply the filter in the DSP.
However, the DSP functions such as arm_fir_f32() have an input data type of float32_t.
We assume that pcm_raw_data is a char type in order to transfer the data, and we think that the essence of pcm_raw_data is float32_t.
How can I treat pcm_raw_data as an input data type float32_t for DSP function input?
-----------------------------------------------------------------------
Thank you in advance.

soeta

[Naeem Maroof]

Hi Soeta,

You can always do the implicit datatype conversions like this. 

In this code, we are converting integer into character, and then back to float.

I am not sure whether you were looking for this, or you have some other question.

It would be nice if you explain your concern in small piece of code.

Regards,

Naeem

Regards,

Naeem