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Configuring I2S Clock on STM32F4?

Question asked by Terence D on Oct 11, 2017
Latest reply on Oct 22, 2017 by Terence D

Hi - I'm attempting to interface a Digilent PmodI2S with my STM32F429 dev board.  The PmodI2S has a Cirrus Logic CS4344 DAC on it.  I'm using System Workbench for STM32 for development and use STM32CubeMX to configure the project.

 

I've configured the STM32F429 I2S as 8 KHz output, using a master clock.  This configuration is shown in the table below:

 

 

By breaking during running the code, I've confirmed all of the I2S values shown in the table above (PLLI2SN, PLLI2SR, I2SDIV and I2SODD) match what I'm seeing in the RCC-PLLI2SCFGR and SPI-I2SPR registers.

 

I'm simply sending a single cycle of a sine wave (256 samples) from my STM32F429 to the PmodI2S.  My PmodI2S is connected to some basic PC speakers.  The audio coming from the speakers is good *EXCEPT* for random "clicks" that occur in the sine wave sound.

 

I've hooked the PmodI2S output up to an oscilloscope and see the "clicks" as shown in the example below:

 

The clicks appear to be random - they don't appear at any regular position in the sine wave cycle.

 

I'm stumped as to what to try next in attempts to get rid of these clicking sounds.  If anyone has any suggestions I would be very appreciative to hear them.  Thanks.

 

-Terence

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