I am working on interfacing Jetson Nano 2GB Dev kit with ADAU7118, a PDM to I2S/TDM Converter which is connected to a PDM microphone.
I have enabled I2S4, BLCK, FSYNC using the jetson-io.py All these ports seem active on the jetson-io.py interface.
To make this system work and listen to audio, I run "arecord -D hw:1,0 -r 48000 -f 32_LE -c 8 -d 20 output.wav. As a result I expect to see 12.28 Mhz signal coming from the BCLK. However, I always see 40-42 Mhz of clock coming from here, even while I am not listening.
I have also looked on modifiying the device tree, and tried to hardcode the clock rate of 12.28 Mhz under i2s@702d1300, but that did not help as well. I have gone over the l4t-3275 guidelines, but could not make it work. I am new to working with audio, and appreciate if you could help.
Best,
Kerem
Hello,
Greetings from NVIDIA and thanks for choosing Jetson Nano!
Can you please confirm that you are setting up the path correctly before initiating arecord? There is an illustration here - Audio Setup and Development — NVIDIA Jetson Linux Developer Guide 1 documentation.
For your case the command would be:
amixer -c 1 cset name=“ADMAIF1 Mux” I2S4
Then start arecord on hw:1,0. Please try out 2 channel, 16 bit audio first, before attempting higher configuration.
Once you start arecord, you can verify that the clock is set up correctly from the clock tree @ /sys/kernel/debug/clk/clk_summary. Ref illustration - Audio Setup and Development — NVIDIA Jetson Linux Developer Guide 1 documentation.
Thanks for the quick response!
Yes I have followed it, I have updated the configuration by entering “amixer -c 1 cset name=“ADMAIF1 Mux” I2S4”. Then checked the clk_summary, I have attached it here. I am not sure but here the clk index starts from 0 so I guess I should be looking at the i2s3, and it shows 1.536 Mhz which is the expected.
But when I try to observe it from the oscilloscope it is stuck on 39 MHz. I have checked that the oscilloscope and its probe are working correctly with other hardware. What would you recommend?
If the I2S clock is OK and the pinmux is OK, then the clock should flow from the pin. Can you please check what clock you get at LRCK pin? Also, are the observed frequencies changing when you change the arecord sample rate (say to 16 kHz)? Also, have you tried probing the pins directly at the 40-pin header without connecting the codec?
