Figure 8-8 Port E Control Register (Pcre) - Motorola DSP56309 User Manual

8.5 GPIO SIGNALS AND REGISTERS
The GPIO functionality of port SCI is controlled by three registers: Port E control register
(PCRE), Port E direction register (PRRE) and Port E data register (PDRE).
8.5.1 Port E Control Register (PCRE)
The read/write, 24-bit PCRE controls the functionality of SCI GPIO signals. Each of the
PC[2:0] bits controls the functionality of the corresponding port signal. When a PC[i] bit
is set, the corresponding port signal is configured as a SCI signal. When a PC[i] bit is
cleared, the corresponding port signal is configured as a GPIO signal. Bits in the Port E
control register appear in Figure 8-8.
7 6 5
13
15 14
21
23 22
Reserved Bit, Read as 0, Should be Written with 0 for Future Compatibility
Note: A hardware RESET signal or a software RESET instruction clears all PCR bits.
8.5.2 Port E Direction Register (PRRE)
The read/write, 24-bit PRRE controls the direction of SCI GPIO signals. When port
signal[i] is configured as GPIO, PDC[i] controls the port signal direction. When PDC[i] is
set, the GPIO port signal[i] is configured as output. When PDC[i] is cleared, the GPIO
port signal[i] is configured as input. Bits in the Port E direction register appear in
Figure 8-9.
MOTOROLA
4 3 2 1
PC2 PC1 PC0
12 11 10 9
20 19 18 17

Figure 8-8 Port E Control Register (PCRE)

DSP56309UM/D
Serial Communication Interface (SCI)
GPIO Signals and Registers
0
Port Control Bits: 1 = SCI
8
16
0 = GPIO
AA0695
8-27