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10.2
ESAI DATA AND CONTROL PINS
Three to twelve pins are required for operation, depending on the operating mode selected and
the number of transmitters and receivers enabled. The SDO0 and SDO1 pins are used by
transmitters 0 and 1 only. The SDO2/SDI3, SDO3/SDI2, SDO4/SDI1, and SDO5/SDI0 pins
are shared by transmitters 2 to 5 with receivers 0 to 3. The actual mode of operation is selected
under software control. All transmitters operate fully synchronized under control of the same
transmitter clock signals. All receivers operate fully synchronized under control of the same
receiver clock signals.
10.2.1
SERIAL TRANSMIT 0 DATA PIN (SDO0)
SDO0 is used for transmitting data from the TX0 serial transmit shift register. SDO0 is an
output when data is being transmitted from the TX0 shift register. In the on-demand mode
with an internally generated bit clock, the SDO0 pin becomes high impedance for a full clock
period after the last data bit has been transmitted, assuming another data word does not follow
immediately. If a data word follows immediately, there is no high-impedance interval.
SDO0 may be programmed as a general-purpose I/O pin (PC11) when the ESAI SDO0
function is not being used.
10.2.2
SERIAL TRANSMIT 1 DATA PIN (SDO1)
SDO1 is used for transmitting data from the TX1 serial transmit shift register. SDO1 is an
output when data is being transmitted from the TX1 shift register. In the on-demand mode
with an internally generated bit clock, the SDO1 pin becomes high impedance for a full clock
period after the last data bit has been transmitted, assuming another data word does not follow
immediately. If a data word follows immediately, there is no high-impedance interval.
SDO1 may be programmed as a general-purpose I/O pin (PC10) when the ESAI SDO1
function is not being used.
10.2.3
SERIAL TRANSMIT 2/RECEIVE 3 DATA PIN (SDO2/SDI3)
SDO2/SDI3 is used as the SDO2 for transmitting data from the TX2 serial transmit shift
register when programmed as a transmitter pin, or as the SDI3 signal for receiving serial data
to the RX3 serial receive shift register when programmed as a receiver pin. SDO2/SDI3 is an
MOTOROLA
Enhanced Serial Audio Interface (ESAI)
DSP56367
ESAI Data and Control Pins
10-3
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