MCF5253 Reference Manual, Rev. 1Freescale Semiconductor 17-1Chapter 17Audio Interface Module (AIM)This chapter discusses the audio interface structure, memory map, and register descriptions, as well astransmit and receive interfaces.17.1 Audio Interface OverviewThe audio interface module provides the necessary input and output features to receive and transmit digitalaudio signals over serial audio interfaces (IIS/EIAJ) and over digital audio interfaces (IEC958).The MCF5253 is equipped with three serial audio interfaces compliant with Philips I 2S and Sony EIAJformat. There are two IEC958 (SPDIF) receivers with 4 multiplexed inputs, and one IEC958 (SPDIF)transmitter with two outputs: One for professional C-channel and one for consumer C-channel.The audio interface module allows the direct retransmission of an audio signal received on one receiver toanother transmitter, without CPU intervention, or it allows the CPU to receive or transmit digital audio toor from any of the audio interfaces.The IEC958 (SPDIF) receivers and transmitter support audio and allow the handling of IEC958 C andU channels.A frequency measurement block exists to allow precise measurement of an incoming sampling frequency.This can be used in conjunction with the XTRIM output (and with the appropriate control software) to“lock” the clock that is being input to CRIN (either external generated clock or crystal) to the recoveredSPDIF audio clock, if so desired. Some external hardware is required for this including a set of varicapdiodes. This is covered in Section 17.9, “Phase/Frequency Determination and XTRIM Function.”
