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Port C Programming Model

6.1 Port C Programming Model

Port C provides three read/write registers:

Port C control (PCC) register

Port C data direction register (PCDDR)

Port C data (PCD) register

These registers are shown in Figure 6-2. The PCC register allows the programming of Port C pins as GPIO pins or as dedicated on-chip peripheral pins. The PCDDR specifies whether a pin programmed as a GPIO pin is an input or an output pin. The PCD register allows accessing data transmitted through a GPIO pin.

Bit-manipulation instructions can be used to access individual bits.

Port C pins associated with the SPI can also be configured as open-drain drivers by the Wired-OR mode (WOM) control bit in the SPI control register (SPCR). More information on the SPCR is available in

Chapter 7, “Serial Peripheral Interface.”

7

PCC— X:$FFED

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1

0

Port C Control Register

CC

CC

CC

CC

CC

CC

CC

CC

CC

CC

CC

CC

CC

CC

CC

CC

Reset = $0000

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Read/Write

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PCDDR— X:$FFEE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Port C Data

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CDD

CDD

CDD

CDD

CDD

CDD

CDD

CDD

CDD

CDD

CDD

CDD

CDD

CDD

CDD

CDD

Direction Register

Reset = $0000

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Read/Write

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PCD— X:$FFEF

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Port C Data Register

CD

CD

CD

CD

CD

CD

CD

CD

CD

CD

CD

CD

CD

CD

CD

CD

Reset = Uninitialized

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Read/Write

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

AA0138

Figure 6-2. DSP56824 Port C Programming Model

6.1.1 Port C Control (PCC) Register

Port C pins can be programmed under software control as GPIO pins or as dedicated on-chip peripheral pins. The Port C control (PCC) register allows the port pins to be selected for one of these two functions. Each Port C pin is independently configured as a GPIO pin if the corresponding condition code (CC) bit is cleared, and is configured as an SPI, SSI, or timer pin if the corresponding PCC register bit is set.

Table 6-1 shows how this bit is defined.

Table 6-1. PCC Bit Definition

CC

Pin Programmed As

 

 

 

 

0

General-purpose I/O pin

 

 

1

Dedicated peripheral pin

 

 

Port C GPIO Functionality

6-3

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