About TX2 DMIC adn MSPK

Robotics & Edge Computing Jetson & Embedded Systems Jetson TX2
1

Does DSP2 and DMIC support SPDM(stereo PDM)in TX2 ? Data on the
rising edge of PDM_CLK is considered left-channel data
while data on the falling PDM_CLK edge is right channel.
If you know the cases above, please share it

2

Hello!

By ‘DSP2’, I believe you are referring to the DSPK interface. Is this correct?

The DSPK and DMIC interfaces both support stereo data. Both the DSPK and DMIC have a LRSEL_POLARITY bit field in their CTRL register that configures if left is following by right or vice versa. The default is left followed by right. The DMIC driver exposes a mixer control that allows the user to configure this from userspace, however, I don’t see such a control for the DSPK.

$ amixer -c tegrasndt186ref cget name='DMIC1 LR Select'
numid=949,iface=MIXER,name='DMIC1 LR Select'
  ; type=ENUMERATED,access=rw------,values=1,items=2
  ; Item #0 'Left'
  ; Item #1 'Right'
  : values=0
$ amixer -c tegrasndt186ref cset name='DMIC1 LR Select' Right

I will confirm if the data on the rising edge by default is left and data on the falling is right. Our documentation is not clear about this.

Regards,
Jon

3

Hello!

I have received confirmation that by default (LRSEL_POLARITY = 0) that left is sampled on the falling edge and right on the rising edge. Setting LRSEL_POLARITY = 1, will cause left to be sampled on the rising edge and right on the falling edge.

Cheers
Jon