required clocks running sw_usb_audio in i2s slave mode
Posted: Fri Oct 26, 2018 1:17 pm
There are possibilities to configure the usb app to run as i2s slave (some discussion in an earlier thread ). In my application I do want to run the app on xcore-200 chip and use it as an usb-to-i2s bridge. I have a DSP that will act as i2s master.
My question is if I still need to supply an audio clock (either 22.6 or 24.6MHz) to the xmos chip (on the MCA board, the clock pins XS1_PORT_1F and XS1_PORT_1L (tile1))?
In principle, the following clock signals should suffice
- LRCLK from DSP
- BCLK from DSP
- 24MHz main processor clock
AudioHwConfig() needs audio clock, but should be fine without since the app is not responsible for any external configurations in my system (e.g. ADC/DAC), besides eventually telling the DSP about the sample rate from the USB.
In my usb_app (example, see thread) I will also perform sample rate conversion with lib_src. But as far as I can see, src_manager does not use the audio clock frequency.
/AJ
My question is if I still need to supply an audio clock (either 22.6 or 24.6MHz) to the xmos chip (on the MCA board, the clock pins XS1_PORT_1F and XS1_PORT_1L (tile1))?
In principle, the following clock signals should suffice
- LRCLK from DSP
- BCLK from DSP
- 24MHz main processor clock
AudioHwConfig() needs audio clock, but should be fine without since the app is not responsible for any external configurations in my system (e.g. ADC/DAC), besides eventually telling the DSP about the sample rate from the USB.
In my usb_app (example, see thread) I will also perform sample rate conversion with lib_src. But as far as I can see, src_manager does not use the audio clock frequency.
/AJ