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Port C GPIO Functionality

6.2.2 Sending Data on Port C GPIO Pins

Example 6-2 shows how to configure Port C pins as GPIO pins and how to use them for sending data.

Example 6-2. Sending Data on Port C GPIO Pins

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

;* OUTPUT 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_o

EQU

$0000

; data output

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

 

 

 

;* Vector setup *

 

 

 

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

 

 

 

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

; Configure PC0-PC15 as GPIO pins (default).

MOVEP

#$FFFF,X:PCDDR

; Select pins PC0-PC15 as output.

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

 

 

 

;* Main routine*

 

 

 

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

 

 

; ...

 

 

 

OUTPUT

 

 

; Output Loop

 

 

 

; ...

MOVE

X:data_o,X0

; Put bits 0-15 of “data_o” on pins PC0-PC15.

MOVEP

X0,X:PCD

; Memory to memory move requires two MOVEs.

BRA

OUTPUT

 

; ...

 

 

 

 

 

 

6-6

DSP56824 User’s Manual

 

Соседние файлы в папке DSP568xx