DSP56303 datasheet(166/292 Pages) FREESCALE

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DSP56303 User’s Manual, Rev. 2

7-34

Freescale Semiconductor

Enhanced Synchronous Serial Interface (ESSI)

7.6.2 Port Direction Registers (PRRC and PRRD)

The read/write PRRC and PRRD control the data direction of the ESSI0 and ESSI1 GPIO signals

when they are enabled by the associated Port Control Register (PCRC or PCRD, respectively).

When PRRC[i] or PRRD[i] is set, the corresponding signal is an output (GPO) signal. When

PRRC[i] or PRRD[i] is cleared, the corresponding signal is an input (GPI) signal. Either a

hardware RESET signal or a software RESET instruction clears all PRRC and PRRD bits.

Table 7-6 summarizes the ESSI port signal configurations.

7.6.3 Port Data Registers (PDRC and PDRD)

Bits 5–0 of the read/write PDRs write data to or read data from the associated ESSI GPIO signal

lines if they are configured as GPIO signals. If a port signal PC[i] or PD[i] is configured as an

input (GPI), the corresponding PDRC[i] pr PDRD[i] bit reflects the value present on the input

7654

3210

PCx5

PCx4

PCx3

PCx2

PCx1

PCx0

Note:

For Px[5–0], a 0 selects Pxn as the signal and a 1 selects the specified ESSI signal. For ESSI0, the GPIO signals are

PC[5–0] and the ESSI signals are STD0, SRD0, SCK0, and SC0[2–0]. For ESSI1, the GPIO signals are PD[5–0] and

the ESSI signals are STD1, SRD1, SCK1, and SC1[2–0].

= Reserved. Read as zero. Write with zero for future compatibility.

Figure 7-18. Port Control Registers (PCRC X:$FFFFBF) (PCRD X:$FFFAF)

PRx5

PRx4

PRx3

PRx2

PRx1

PRx0

Note:

For bits 5–0, a 0 configures PRxn as a GPI and a 1 configures PRxn as a GPO. For ESSI0, the GPIO signals are

PC[5–0]. For ESSI1, the GPIO signals are PD[5–0]. The corresponding direction bits for Port C GPIOs are PRC[5–0].

The corresponding direction bits for Port D GPIOs are PRD[5–0].

= Reserved. Read as zero. Write with zero for future compatibility.

Figure 7-19. Port Direction Registers (PRRC X:$FFFFBE) (PRRD X: $FFFFAE)

Table 7-6. ESSI Port Signal Configurations

PCRC/PCRD[i]

PRRC/PRRD[i]

Port Signal[i] Function

ESSI0/ESSI1

Port C/Port D GPI

Port C/Port D GPO

X: The signal setting is irrelevant to the Port Signal[i] function.

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