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Port C Programming Examples

6.2.1 Receiving Data on Port C GPIO Pins

Example 6-1 shows how to configure Port C pins as GPIO pins and how to use them for receiving data.

 

Example 6-1. Receiving Data on Port C GPIO Pins

;*********************

;* INPUT example

*

;* for Port C

*

;* of DSP56824 chip

*

;*********************

 

 

 

START

EQU

$0040

; Start of program

 

BCR

EQU

$FFF9

; Bus Control Register

 

PCC

EQU

$FFED

; Port C Control Register

 

PCD

EQU

$FFEF

; Port C Data

 

PCDDR

EQU

$FFEE

; Port C Data Direction Register

 

data_i

EQU

$0001

; data input

 

;**************

 

 

 

;* Vector setup*

 

 

 

;**************

 

 

 

;+-----------------------------------------------------------------------

 

 

 

+

;| Note: Bootstrap ROM configures OMR (operating mode register) to set

|

;|

chip operating mode for Mode 2 (Normal Expanded Mode), then

|

;|

jumps to first location of internal program RAM (P:$0000).

|

;+-----------------------------------------------------------------------

 

 

 

+

ORG

P:$0000

; Cold Boot

JMP

START

; also Hardware RESET vector (Mode 0, 1, 3)

ORG

P:$E000

; Warm Boot

JMP

START

; Hardware RESET vector (Mode 2)

ORG

P:START

; Start of program

;**************

 

 

;* General setup*

 

;**************

 

 

MOVEP

#$0000,X:BCR

; External Program memory has 0 wait states.

 

 

; External data memory has 0 wait states.

 

 

; Port A pins are tri-stated when no

;**************

 

; external access occurs.

 

 

;* Port C setup*

 

 

;**************

 

 

MOVEP

#$0000,X:PCC

; Configures PC0-PC15 as GPIO pins (default)

MOVEP

#$0000,X:PCDDR

; Selects pins PC0-PC15 as input (default)

;**************

 

 

;* Main routine*

 

 

;**************

 

; ...

 

 

INPUT

 

; Input Loop

 

 

; ...

MOVEP

X:PCD,X0

; Read PC0-PC15 into bits 0-15 of “data_i”

MOVE

X0,X:data_i

; (memory to memory move requires two moves)

BRA

INPUT

; ...

 

 

 

 

Port C GPIO Functionality

6-5

Соседние файлы в папке DSP568xx