Freescale Semiconductor DSP56366 - Manual (Page 153)

ESAI Data and Control Pins
DSP56366 24-Bit Digital Signal Processor User Manual, Rev. 4
Freescale Semiconductor 8-3
8.2 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.
8.2.1 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.
8.2.2 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.
8.2.3 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 input when data is being received by
the RX3 shift register. SDO2/SDI3 is an output when data is being transmitted from the TX2 shift register.
In the on-demand mode with an internally generated bit clock, the SDO2/SDI3 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.
SDO2/SDI3 may be programmed as a general-purpose I/O pin (PC9) when the ESAI SDO2 and SDI3
functions are not being used.