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Enhanced Serial Audio Interface (ESAI)
ESAI Initialization Examples
10.6
ESAI INITIALIZATION EXAMPLES
10.6.1
INITIALIZING THE ESAI USING INDIVIDUAL RESET
•
The ESAI should be in its individual reset state (PCRC = $000 and PRRC = $000). In
the individual reset state, both the transmitter and receiver sections of the ESAI are
simultaneously reset. The TPR bit in the TCR register may be used to reset just the
transmitter section. The RPR bit in the RCR register may be used to reset just the
receiver section.
•
Configure the control registers (TCCR, TCR, RCCR, RCR) according to the operating
mode, but do not enable transmitters (TE5–TE0 = $0) or receivers (RE3–RE0 = $0). It
is possible to set the interrupt enable bits which are in use during the operation (no
interrupt occurs).
•
Enable the ESAI by setting the PCRC register and PRRC register bits according to
pins which are in use during operation.
•
Write the first data to be transmitted to the transmitters which are in use during
operation.
This step is needed even if DMA is used to service the transmitters.
•
Enable the transmitters and receivers.
•
From now on ESAI can be serviced either by polling, interrupts, or DMA.
Operation proceeds as follows:
•
For internally generated clock and frame sync, these signals are active immediately
after ESAI is enabled (step 3 above).
•
Data is received only when one of the receive enable (REx) bits is set and after the
occurrence of frame sync signal (either internally or externally generated).
•
Data is transmitted only when the transmitter enable (TEx) bit is set and after the
occurrence of frame sync signal (either internally or externally generated). The
transmitter outputs remain tri-stated after TEx bit is set until the frame sync occurs.
10.6.2
INITIALIZING JUST THE ESAI TRANSMITTER SECTION
•
It is assumed that the ESAI is operational; that is, at least one pin is defined as an ESAI
pin.
•
The transmitter section should be in its personal reset state (TPR = 1).
10-56
DSP56367
MOTOROLA
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