MC I2S audio interface

The documentation for the I2S interfacing is confusing and contradictory in alot of cases. This posting is intended to clear alot of this up and provide a reference point. Main points to make are.

  • The direction (with exception noted below) and voltage levels of the I2S interface have not changed even though naming between units MC879x, MC870x and MC73xx has changed.
  • The main error in the current documentation is in the hardware integrators guide where the direction of the pins is incorrect.
  • The major functional difference in the new units (MC73xx) is the switch from being an I2S slave in MC8704 to an I2S master in MC73xx. This obviously changes the direction of the clock and word select lines but the data line direction remains the same but will significantly impact drop in compatibility and system architecture.

The attached document shows the status of the pins as per the documentation (some of the documents are not posted on the current dev zone i.e. v5.1 of the MC8704 PTS) but hopefully should be.

I2S audio on MC units.docx (15.8 KB)


Thanks for the information. Will go through this and might get a updated document. Thanks