# Analog MIC issue while connecting PCM interface

**URL:** <https://forum.sierrawireless.com/t/analog-mic-issue-while-connecting-pcm-interface/6088>\
**Category:** General wireless topics FAQ\
**Created:** [January 23, 2013, 9:40am UTC](https://forum.sierrawireless.com/t/analog-mic-issue-while-connecting-pcm-interface/6088 "2013-01-23T09:40:44Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![FAQ\_Poster](https://avatars.discourse-cdn.com/v4/letter/f/f9ae1b/32.png) [@FAQ\_Poster](https://forum.sierrawireless.com/u/FAQ_Poster)\
**Post date:** [January 23, 2013, 9:40am UTC](https://forum.sierrawireless.com/t/analog-mic-issue-while-connecting-pcm-interface/6088/1 "2013-01-23T09:40:44Z")

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The PCM\_IN signal should be in HiZ state if the PCM interface is not used, if this signal is tied to ground, the analog microphone won’t work.