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GPIO Programming Model
DSP56364 24-Bit Digital Signal Processor Users Manual, Rev. 2
Freescale Semiconductor 5-3
Port B Direction Register (PRRB)
The read/write Port B Direction Register controls the direction of data transfer for each GPIO pin.
5.2.1.3 PRRB Direction Bits (PDC[3:0]) - Bits 3-0
When PDC[i] is set, the GPIO port pin[i] is configured as output. When PDC[i] is cleared the GPIO port
pin[i] is configured as input. See Table 5-1. Hardware and software reset clear the PDC[3:0] bits.
5.2.1.4 PRRB Reserved Bits - Bits 23-4
These bits are reserved and unused. They read as 0s and should be written with 0s for future compatibility.
5.2.2 Port B GPIO Data Register (PDRB)
The read/write Port B Data Register (PDRB) is used to read data from or write data to the GPIO pins.
5.2.2.1 PDRB Data Bits (PD[3:0]) - Bits 3-0
If a GPIO pin [i] is configured as a GPIO input, then the corresponding PD[i] bit will reflect the value
present on this pin. If a GPIO pin [i] is configured as a GPIO output, then the value written into the
corresponding PD[i] bit will be reflected on the pin. The PD[3:0] bits are not affected by hardware or
software reset.
5.2.2.2 PDRB Reserved Bits - Bits 23-4
These bits are reserved and unused. They read as 0s and should be written with 0s for future compatibility.
Table 5-1 GPIO Pin Configuration
PDC[i] PC[i] GPIO Pin[i] Function
0 0 Three-Stated (Disconnected)
01Input
1 0 Output
1 1 Open-drain output