I2S

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I²S stands for Inter Integrated Sound and is similar to the I²C which is used for transmitting data between Chips on a circuit board. (wikipedia article on I²S). I²S is used for connecting digital audio devices together, (for example between the main processor and the audio codec chip on cell phones or computers or between the CD transport and the DAC in a CD player).
I2S interface consists of at least 3 signals:
  1. Clock
  2. Left right clock
  3. Data line

The eKA8562A Chip which is a USB Audio Controller (and can be used as an oscilloscope) sports an I²S interface. Here are a few signals captured at the various pins (I²S output) on this chip:


Pin 5 of eKA8562A - I²S BCLK Output
Clock - This signal is used as the clock to latch in the bits appearing on the data line.



Pin 6 of eKA8562A - I²S LRCLK Output
Left Right Clock - This signal is used to tell the receiving device whether the data being received by it on the data line is meant for the left audio channel or the right audio channel.



Pin 7 of eKA8562A - I²S SDATA Output
Data - This signal carries the actual PCM audio data alternately for the left and the right audio channels.



12MHz Clock on a USB Device: Pin 4 of eKA8562A
(Since eKA8562A is a USB device, it uses a 12MHz Crystal as its clock source)

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