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Chapter 40 Synchronous Audio Interface (SAI)
40.5.6 Word mask register
The SAI transmitter and receiver each contain a word mask register, namely TMR and
RMR, that can be used to mask any word in the frame. Because the word mask register is
double buffered, software can update it before the end of each frame to mask a particular
word in the next frame.
The TMR causes the Transmit Data pin to be tri-stated for the length of each selected
word and the transmit FIFO is not read for masked words.
The RMR causes the received data for each selected word to be discarded and not written
to the receive FIFO.
40.5.7 Interrupts and DMA requests
The SAI transmitter and receiver generate separate interrupts and separate DMA requests,
but support the same status flags. Asynchronous versions of the transmitter and receiver
interrupts are generated to wake up the CPU from stop mode.
40.5.7.1 FIFO warning flag
The FIFO warning flag is set based on the number of entries in the FIFO.
The transmit warning flag is set when the number of entries in any of the enabled
transmit FIFOs is empty and is cleared when the number of entries in each enabled
transmit FIFO is not empty.
The receive warning flag is set when the number of entries in any of the enabled receive
FIFOs is full and is cleared when the number of entries in each enabled receive FIFO is
not full.
The FIFO warning flag can generate an Interrupt or a DMA request.
40.5.7.2 FIFO error flag
The transmit FIFO error flag is set when the any of the enabled transmit FIFOs
underflow. After it is set, all enabled transmit channels will transmit zero until
TCSR[FEF] is cleared and the next transmit frame starts. All enabled transmit FIFOs
must be reset and initialized with new data before TCSR[FEF] is cleared.
KL27 Sub-Family Reference Manual , Rev. 5, 01/2016
Freescale Semiconductor, Inc.
819
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