In mono mode, the samples you get are in the order 1,0,3,2,5,4,..., so depending on what you want to use them for you may have to swap samples 0<->1, 2<->3, 4<->5,... Shouldn't affect the frequencies much though.


that is for the Big/Little endians word order correction on the int32 ?
this is ...

Sorry, yes its a pulldown and just measured 54K, so ok.

My esp is a esp32-c3.

The inmp441 (and many other i2s devices) creates 24 bits per sample/ADCconversion.
But there is no natural dataype of int24, only int8,int16,int32,int64.
So it is programmed to output the 24bits as a int32, where the low-byte is set to 0.
Thus the 24bit of pcm-data are located on the high side of ...

just confirming my "artifacts in the low-bye:

using I2S_STD_MSB_SLOT_DEFAULT_CONFIG:

...
val:0x000015e0
val:0x000030e0
val:0x00003fe0
val:0x7ffe4ae0 -neg value
val:0x0000a3e0
val:0x7fffa6e0 -neg value
...

using I2S_STD_PHILIPS_SLOT_DEFAULT_CONFIG:
...
val:0x000151c0
val:0x00040fc0
val:0xffffd5c0 ...

int32_t val32 = input_buffer[i] >> 8; // shift out the empty byte - this is a signed int, the shift will preserve the sign
int16_t val16 = (int16_t)val32; // convert 32 bit signed to 16 bit signed


Assuming you inited the i2s to transport 32bit values, you will get 32bit values.
int16_t val16 ...

Just having the same problem.

yes, right-shift by 8 gives the proper 24bit.

just leaving it as is, gives amplification by 256.

however, inspecting the data, i do see, that the low-byte is not always 00, but sometimes C0 , so some artifacts going on.

hmm?? that is strange.



Also one should note ...

Hello forum,

i am currently monitoring a signal input for a specific voltage level to be reached.

running adc1 in continuous mode and have the monitor enabled for a specific high_threshold.

That works fine.

However, i need to change the high_threshold frequently to adjust for changing ...

Hi everyone,

I have a bunch of esp32-cams here.

I wonder if there is an adapterboard with flexcable on the market that can be used to be inserted into the cam connector.
So one can use it for alternate hardware.

thanks

The example code here
https://github.com/espressif/esp-idf/tree/master/examples/peripherals/i2s/i2s_basic/i2s_pdm
will support stereo input.

mic left = L/R select to Vdd. Dataout on CLK high
mic right=L/R select to GND. Dataout on CLK low

i build this setup, however getting a noise when both mics ...

Make shure the mic is getting 3.3V supply.
too low volume happens if supply is just 1.8 or so.