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ad1974 configuration of sampling frequency 8kHz and 16kHz

Question asked by tsy333 on Nov 27, 2017
Latest reply on Dec 4, 2017 by tsy333

Hello, I am new to this area.

I am using AD1974 with a stm32f401 mcu, I need to configure an sampling frequency of 8kHz and 16kHz in my application of audio in.

However in the datasheet of ad1974, I found there are no such option in adc control 0 register.


ADC Control 0 [7:6]

00    32 kHz/44.1 kHz/48 kHz                        

01    64 kHz/88.2 kHz/96 kHz

10    128 kHz/176.4 kHz/192 kHz

11     Reserved


And I checked here and found similar problem about ad1937. So I do it as following:

PLLCC0: 0x81 (Enable ADC, PLL disabled)

PLLCC1: 0x03 (Clock sources = MCLK)

And now if I want to configure a 16khz sampling rate. Since I select a INPUT 256 (×44.1 kHz or 48 kHz) as default. I need to provide a mclkin of 256*16k = 4Mhz. Is it correct?