# Analog MIC issue while connecting PCM interface

**URL:** <https://forum.sierrawireless.com/t/analog-mic-issue-while-connecting-pcm-interface/6039>\
**Category:** General wireless topics\
**Created:** [January 2, 2013, 1:14pm UTC](https://forum.sierrawireless.com/t/analog-mic-issue-while-connecting-pcm-interface/6039 "2013-01-02T13:14:22Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![CKD](https://avatars.discourse-cdn.com/v4/letter/c/7feea3/32.png) [@CKD](https://forum.sierrawireless.com/u/CKD)\
**Post date:** [January 2, 2013, 1:14pm UTC](https://forum.sierrawireless.com/t/analog-mic-issue-while-connecting-pcm-interface/6039/1 "2013-01-02T13:14:22Z")

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In order not to disturb the analog microphone, the PCM\_IN signal should be in HiZ state when the PCM interface is used; or not connected when it’s not used. The PCM\_IN should not linked to ground.