Wp7607 pcm_in

IoT Modules
1

Hi,
I built a setup with a WP7607 mounted on a mangOH green board and a µC to send and receive audio data using the PCM WP7607 interface.
The µC acts as Master and the WP7607 as slave. To match the required voltage level of the slave, a level shifter is used to shift down the signal of the master from 3.3 V to 1.8 V. Another level shifter shift the level of the PCM_OUT signal up.
With this configuration, the PCM_OUT pin from the WP7607 sends correctly the data to the µC. However, as soon as I connect the PCM_IN signal between the mangOH board and the level shifter, the voltage drops to 300 mV. Consequently, a signal can’t be correctly transmitted between the µC and the WP7607, and, after establishing a call, the modem doesn’t produce any audible signal. The other signals (PCM_SYNC and PCM_CLK) keep their level (1.8 V) without any voltage drop.
To setup the PCM interface I used the following commands

at!avpifacepref?
!AVPIFACEPREF: F

at!avcfg=0,1,0,0,0,0,0,2
OK

at!avcfg?
!AVCFG: 0,1,0,0,0,0,0,2

at!avsetprofile?
!AVSETPROFILE: 0,0,0,0,3,0

Is there any other related command to correctly setup the interface?

2

Hi,
By default, PCM was not included so PCM could not be set with AT!AVCFG without first setting AT!AVPIFACEPREF=F.
Could you try with below commands:

  • AT!AVPIFACEPREF=F
  • AT!AVCFG=0,0,0,0,0,0,0,2
  • AT!AVSETPROFILE=0

Thanks,

3

Hi,
Thank you for the reply. I’ve tried your suggested commands but the high-level on the PCM_IN line is still at 300 mV

4

Hi,
What firmware are you using?
Could you help to check: ATI8, ATI9, AT!SELRAT?, AT+COPS?, AT+WIOCFG?
Did you use Legato application to handle audio or only AT command?
And please check the voltage after level shifter before you connect to PCM_IN.

Thanks,