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STM32F4 Discovery 'Audio_playback_and_record' demo and reducing CPU clock.

Question asked by cray.ruslan on Feb 13, 2014
Latest reply on Feb 17, 2014 by cray.ruslan
Dear Colleagues,

Thank you for the good Evaluation Kit. 

For one of the project I use 'Audio_playback_and_record' demo application as a reference. When I use default SYSCLK/HCLK 168 MHz the demo records audio, and I see pretty clear signal with no distortion.

Then I want to reduce CPU clock frequency to 84 MHz. So I use 'System Clock Configuration' Excel-tool to generate new system_stm32f4xx.c file. Then I copy/replace this file to 'Audio_playback_and_record' project, recompile, download and run. I see that distortion occurs. If you need I can provide pictures by e-mail.

How can I record clear audio signal with CPU clock frequency lower than 168 MHz?