Operating Modes - Motorola DSP56367 User Manual

Enhanced Serial Audio Interface (ESAI)

Operating Modes

After hardware or software reset, the RSM register is preset to $FFFFFFFF, which means that
all 32 possible slots are enabled for data reception.
Note: When operating in normal mode, bit 0 of the mask register must be set to one,
otherwise no input is received.
10.4 OPERATING MODES
ESAI operating mode are selected by the ESAI control registers (TCCR, TCR, RCCR, RCR
and SAICR). The main operating mode are described in the following paragraphs.
10.4.1 ESAI AFTER RESET
Hardware or software reset clears the port control register bits and the port direction control
register bits, which configure all ESAI I/O pins as disconnected. The ESAI is in the individual
reset state while all ESAI pins are programmed as GPIO or disconnected, and is active only if
at least one of the ESAI I/O pins is programmed as an ESAI pin.
10.4.2 ESAI INITIALIZATION
The correct way to initialize the ESAI is as follows:
1. Hardware, software, ESAI individual, or STOP reset.
2. Program ESAI control and time slot registers.
3. Write data to all the enabled transmitters.
4. Configure at least one pin as ESAI pin.
During program execution, all ESAI pins may be defined as GPIO or disconnected, causing
the ESAI to stop serial activity and enter the individual reset state. All status bits of the
interface are set to their reset state; however, the control bits are not affected. This procedure
allows the DSP programmer to reset the ESAI separately from the other internal peripherals.
During individual reset, internal DMA accesses to the data registers of the ESAI are not valid
and data read is undefined.
The DSP programmer must use an individual ESAI reset when changing the ESAI control
registers (except for TEIE, REIE, TLIE, RLIE, TIE, RIE, TE0-TE5, RE0-RE3) to ensure
proper operation of the interface.
10-48 DSP56367 MOTOROLA