# BC127 I2S input

**URL:** <https://forum.sierrawireless.com/t/bc127-i2s-input/15300>\
**Category:** Uncategorized\
**Created:** [February 8, 2019, 7:16pm UTC](https://forum.sierrawireless.com/t/bc127-i2s-input/15300 "2019-02-08T19:16:14Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![beau\_rogers](https://avatars.discourse-cdn.com/v4/letter/b/898d66/32.png) [@beau\_rogers](https://forum.sierrawireless.com/u/beau_rogers)\
**Post date:** [February 8, 2019, 7:16pm UTC](https://forum.sierrawireless.com/t/bc127-i2s-input/15300/1 "2019-02-08T19:16:14Z")

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Hello,

I am trying to get the BC127 to take an I2S input and output the sound onto my bluetooth speakers.  
The I2S input that I am using is a simple 440Hz square wave with a sample rate of 8000Hz and 16 bit sampling and in Left\_Justified\_Mode. I am doing this using this arduino sample code and setup:  
[https://www.arduino.cc/en/Tutorial/I2SSimpleTone](https://www.arduino.cc/en/Tutorial/I2SSimpleTone)

The two are connected: Arduino pin---------BC127 pin  
LRC---------WS  
DIN---------SD\_IN  
BCLK---------SCK  
GND--------GND

I have the BC127 configuration as:  
Version: V7.2  
AUDIO=1 0  
AUDIO\_DIGITAL=0 8000 1 100200 ON  
My understanding is that I want the AUDIO\_DIGITAL set such that it has 16 bits/sample, set to slave, left justified and I don’t think the BCLK prescaling matters when in slave mode.

When I run the code and connect my Bluetooth headphones, I get no sound (not even the ‘pop’ when I run the PLAY command). What else might need to be set up on my AUDIO\_DIGITAL?

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**Author:** ![beau\_rogers](https://avatars.discourse-cdn.com/v4/letter/b/898d66/32.png) [@beau\_rogers](https://forum.sierrawireless.com/u/beau_rogers)\
**Post date:** [February 11, 2019, 8:46pm UTC](https://forum.sierrawireless.com/t/bc127-i2s-input/15300/2 "2019-02-11T20:46:45Z")

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I eventually solved my own problem. There ended up being a few things that I was doing wrong. First, I made a silly hardware error where I had the SPI\_PCM# pin pull up to 3.3V rather than being pulled to ground. Second, bit 2 of \<param\_2\> needs to be set to crop down to 16 bits. Third, the sampling rate needed to be higher, so I configured the Aurduio and BC127 for a sampling rate of 48000. This results in my settings as AUDIO\_DIGITAL=0 48000 1 100204 OFF.