from i2s audio to ble streaming

[chaabani]

Hi 

i am using the sdk 14.0

i am working with sph0645 i2s microphone , i have tested the microphone and it is working fine with the nrf 52 on 912600 baud rate. Now i wan't to stream that audio via bleutooth to a mobile phone.

The problem is  the 912600 baudrate gives 912600 bits per second and the bleutooth is up to 12200 bit per second,  so the real time streaming is impossible! 

is there a solution to compress the data or any other solution ?

[Kong_Scott]

Hi hch!

I'm very happy to find someone that success using sph0645. Actually I am confused using that microphone.

I connected 

BCLK              -      SCLK

DATA OUT      -      SDIN

WS                  -      LRCK

just like this.

But the data only I can get  is

<info> app:   1: 0000/0000, expected: CAFD/CAFF (i: 2).

What should I change? I'm using SDK15, i2s example.

Please let me know.

Best regard.

Scott

[chaabani]

Hi Kong_scott

the problem is that the nrf52 support only 24 bits and this microphone works with 32 bits. 
So we need to change the clk of the i2s of the microphone. here is the solution that i found on github https://github.com/gregtomasch/nRF52_24-bit-_I2S_Microphone_Audio_Recording_Utility

best regards 
houssem

[Kong_Scott]

Thank you for your help.It is very useful.

But I'm confused somehow.

Which version of SDK did you use ? I'm using SDK 15.0.

Especially, function 

err_code = app_pwm_ticks_init(&PWM1,&pwm1_cfg,pwm_ready_callback);

is not working.

Can you please let me know, Which C file include that function ?

I'm using perfectly same sensor with you. 

Thanks again.

Scott

[chaabani]

Hi Scott 

i tested the microphone with sdk13 and sdk14 and it is working fine in the two cases.
maybe you forgot to change the app_pwm.c as noted in the github link.

kind regards 
Houssem

[Kong_Scott]

Hi 

I finally solve that C file problem. I didn't know app_pwm.c was included in the example file.

But next problem is Clock frequency.

I saw on datasheet shp0645 support 2048MHz~4096MHz (BCLK). Then do I have to change 

BCLK,LRCK CLOCK ?

Did you change it? 

Thank you

SCOTT

[chaabani]

Hi 
no you don't need to change, it the same clock frequency of the microphone used in that exemple.

best regards 
Houssem