DSP56303 FREESCALE [Freescale Semiconductor, Inc], DSP56303 Datasheet - Page 190

• Manufacturer Part Number: DSP56303
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Serial Communication Interface (SCI)
addresses. If SCKP is set and SSHTD is set, SCI Synchronous mode is equivalent to the SSI
operation in 8-bit data on-demand mode.
Note:
8.7 GPIO Signals and Registers
Three registers control the GPIO functionality of the SCI pins: Port E control register (PCRE),
Port E direction register (PRRE) and Port E data register (PDRE).
8.7.1 Port E Control Register (PCRE)
The read/write PCRE controls the functionality of SCI GPIO signals. Each of the PCRE[2–0] bits
controls the functionality of the corresponding port signal. When a PCRE[i] bit is set, the
corresponding port signal is configured as an SCI signal. When a PC[i] bit is cleared, the
corresponding port signal is configured as a GPIO signal. A hardware
RESET instruction clears all PCRE bits.
8.7.2 Port E Direction Register (PRRE)
The read/write PRRE controls the direction of SCI GPIO signals. When port signal[i] is
configured as GPIO, PRRE[i] controls the port signal direction. When PRRE[i] is set, the GPIO
port signal[i] is configured as output. When PRRE[i] is cleared, the GPIO port signal[i] is
8-22
Note:
23
11
For bits 2–0, a 0 selects PEn as the signal and a 1 selects the specified SCI signal.
= Reserved. Read as zero. Write to zero for future compatibility.
When data is written to a peripheral device, there is a two-cycle pipeline delay until
any status bits affected by this operation are updated. If you read any of those status
bits within the next two cycles, the bit does not reflect its current status. For details see
the DSP56300 Family Manual.
22
10
21
Figure 8-8. Port E Control Register (PCRE X:$FFFF9F)
9
20
8
DSP56303 User’s Manual, Rev. 2
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7
18
6
17
5
16
4
15
3
RESET
SCLK
PE2/
14
2
signal or a software
Freescale Semiconductor
PE1/
TXD
13
1
PE0/
RXD
12
0