I am trying to set up an application to use a BF548 DSP connected to an AD1938 with two aux ADCs over the SPORT1 interface. I have functioning software that operates the ADCs and DACs at a sample rate of 48kHz, using a circular DMA descriptor chain and multichannel mode. I need to increase the DAC sample rate to 192kHz, and am struggling with getting the correct register settings for such a configuration to operate.
I have a ~12MHz MCLK to the AD1938, the ADCs configure for 48KHz Serial AUX mode, and the DACs for Dual line TDM with a sample rate of only 192KHz. I require 4 ADC channels from the AD1938 and 3 channels from two aux ADCs, and 2 DAC channels on the AD1938 to operate at the aforementioned rates.
Is this configuration possible?
Current register settings for SPORT1
Blue: TX sine wave (currently attempting 10kHz wave @ 96KHz, before moving to 192KHz)
Purple: RX sine wave (distorted)
Actual wave, distorted, actually at 2500Hz instead of 10kHz:
It seems the device is close, but the clock or something just is not right. Any help is appreciated.
Hi,I understand that you are using ADSP-BF548 SPORT1 multichannel mode for communicating with a codec(ADAD1938). In order to assist you better on this, can you please get back on the below points?1. Can you explain your application in brief. A simple block diagram would be useful for understanding your requirement/issue easily.2. I could see you are using SPORT1. Are you using any other SPORTs other than this for connecting to CODEC?3. How many channel TDM are you using?4. Is it that you want ADC's sample rate at 48KHz and DAC's sample rate at 192KHz?Regards,Anand Selvaraj.
1) I have 2 stereo aux adcs connected to an AD1938, that is connected to SPORT1 of the DSP
I believe that I had my issues resolved, in the sense that I received answers indicating what I am attempting is not possible. The BF548 SPORT multichannel mode requires the same FS, and therefore cannot drive the TX/RX sides of the AD1938 differently. Additionally, the AD1938 does not support doing a TDM8 (4 on chip and 4 aux adcs) at more than 48KHz. To achieve my desired functionality would require a redesign of the board to either:
1) Connect a second SPORT to the AD1938 and drive separate TX and RX FS
2) Connect a second AD1938 to the SPORT and remove the AUX ADCs, and then the sample rate could be increased when only using 4 ADC channels.
Hi,Thanks for the update.Regards,Anand Selvaraj
I support the 1938.
It can operate at TDM8 at up to 96kHz. It can also operate the ADC and the DAC sides at different sample rates and settings. I just needed to correct this in this thread.
I am not sure if the hardware platform you are using is flexible enough to be able to operate the part in this way.