# Wp7607 pcm\_in

**URL:** <https://forum.sierrawireless.com/t/wp7607-pcm-in/19177>\
**Category:** IoT Modules\
**Created:** [January 29, 2020, 3:09pm UTC](https://forum.sierrawireless.com/t/wp7607-pcm-in/19177 "2020-01-29T15:09:24Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![am.tude](https://avatars.discourse-cdn.com/v4/letter/a/df788c/32.png) [@am.tude](https://forum.sierrawireless.com/u/am.tude)\
**Post date:** [January 29, 2020, 3:09pm UTC](https://forum.sierrawireless.com/t/wp7607-pcm-in/19177/1 "2020-01-29T15:09:24Z")

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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?

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<div class="post-metadata">

**Author:** ![jerdung](https://avatars.discourse-cdn.com/v4/letter/j/82dd89/32.png) [@jerdung](https://forum.sierrawireless.com/u/jerdung)\
**Post date:** [January 31, 2020, 9:59am UTC](https://forum.sierrawireless.com/t/wp7607-pcm-in/19177/2 "2020-01-31T09:59:47Z")

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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,

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<div class="post-metadata">

**Author:** ![am.tude](https://avatars.discourse-cdn.com/v4/letter/a/df788c/32.png) [@am.tude](https://forum.sierrawireless.com/u/am.tude)\
**Post date:** [January 31, 2020, 12:59pm UTC](https://forum.sierrawireless.com/t/wp7607-pcm-in/19177/3 "2020-01-31T12:59:45Z")

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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

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<div class="post-metadata">

**Author:** ![jerdung](https://avatars.discourse-cdn.com/v4/letter/j/82dd89/32.png) [@jerdung](https://forum.sierrawireless.com/u/jerdung)\
**Post date:** [February 3, 2020, 7:23am UTC](https://forum.sierrawireless.com/t/wp7607-pcm-in/19177/4 "2020-02-03T07:23:50Z")

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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,