Linux/AM5728: McASP data acquisition from ADS1602

Hi Pavel,

Thanks for tip on the ADS117x codec. If ALSA can only support up to 96 kHz sample rate, then it sounds like it is not the correct approach I should take for the ADS1602 since it has a 2.5 MHz sample rate. My other thought is to develop a low level driver and loadable kernel module. Does TI have any good resources/references on a lower level McASP driver for linux?

I know RTOS has a low level driver, and the CSL drivers can be used for bare-metal applicaitons, but I don't see anything other than ALSA wrapping on the Linux side. RTOS and bare-metal applications are options, but both would require additional development to get a SATA hard-drive working. My understanding is RTOS does not support SATA at this time.

Thanks,
Alex.

Alex,

ARob109 said:

Thanks for tip on the ADS117x codec. If ALSA can only support up to 96 kHz sample rate, then it sounds like it is not the correct approach I should take for the ADS1602 since it has a 2.5 MHz sample rate.

This limitation comes from external audio codec used in EVM, AIC3104. This codec support up to 96KHz sample rate. The McASP module itself support up to 1.5625MHz sample rate (for 16bit audio, 2 channels), but this is still under 2.5MHz.

ARob109 said:

My other thought is to develop a low level driver and loadable kernel module. Does TI have any good resources/references on a lower level McASP driver for linux?

We have only one McASP linux driver:

linux-kernel/sound/soc/davinci/davinci-mcasp.c

ARob109 said:

I know RTOS has a low level driver, and the CSL drivers can be used for bare-metal applicaitons, but I don't see anything other than ALSA wrapping on the Linux side. RTOS and bare-metal applications are options, but both would require additional development to get a SATA hard-drive working. My understanding is RTOS does not support SATA at this time.

I can not comment regarding AM57x RTOS. You need to open new e2e thread regarding AM57x RTOS.

Regards,
Pavel

Pavel,

Can the methods in linux-kernel/sound/soc/davinci/davinci-mcasp.c be used directly from user-space or is this driver only to facilitate the use of ALSA at a higher level?

If the driver API is not available in user-space then my assumption is I need develop a loadable kernel driver to create a "/dev/mcasp" device that I can then make calls to with a user application.

Thanks.

Arob,

linux-kernel/sound/soc/davinci/davinci-mcasp.c driver can be used only at kernel level. In user space we have ALSA API that invoke this kernel driver. Check below pointers for more info:

processors.wiki.ti.com/.../Sitara_SDK_Linux_Audio_ALSA_User_Space
processors.wiki.ti.com/.../Sitara_Linux_Audio_Sample_Application_Overview
processors.wiki.ti.com/.../AM335x_Audio_Driver's_Guide

Regards,
Pavel