NRF52 PDM Frequency Calculation

RE: NRF52 PDM Frequency Calculation

Jared — Fri, 18 Feb 2022 14:56:38 GMT

Confirmed from our developers, this is valid for the nRF52 series as well.

RE: NRF52 PDM Frequency Calculation

Jared — Wed, 16 Feb 2022 14:34:51 GMT

Hi,

I think that should also be valid for the nRF52 series.

Let me double check with our developers and come back to you!

regards

Jared

RE: NRF52 PDM Frequency Calculation

Guilherme Costa — Mon, 14 Feb 2022 15:50:48 GMT

By the way, I just found this in the Product Specification for the nrf5340:

Does this equation hold true in the nrf52 series as well?

RE: NRF52 PDM Frequency Calculation

Guilherme Costa — Mon, 14 Feb 2022 15:18:17 GMT

Hi Jared.

For this end, I want to know the formula for calculating the CLK frequency, since the value provided in the Product Specification don't seem to bear a direct relationship with the generated signal frequency.

This is exactly what I mean. I might be missing something, but I couldn't figure out how the values in the table relate to the divisor values shown (like, how setting the register to 0x08000000 gives us a divisor of 32).

RE: NRF52 PDM Frequency Calculation

Jared — Mon, 14 Feb 2022 12:59:47 GMT

Hi,

[quote user=""]For this end, I want to know the formula for calculating the CLK frequency, since the value provided in the Product Specification don't seem to bear a direct relationship with the generated signal frequency.[/quote]

What do you mean, the formula is shown in the register description. The PDM clock frequency is adjusted by the PDMCLKCTRL register. Do you mean there isn't a clear connection between the value that you write to the PDMCLKCTRL register and the value that is used to divide the 32 MHz clock and thus set the clock frequency?

regards

Jared

RE: NRF52 PDM Frequency Calculation

hmolesworth — Fri, 11 Feb 2022 19:43:23 GMT

You might find this I2S_Microphone_Audio_Recording_Utility more than helpful though not quite what you asked