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; (SPE) SPI disabled. ; Configure:
; (SPR) SPI Clock Rate Select at /1
; [irrelevant; mentioned for completeness] ; (SPIE) SPI Interrupt disabled.
; (WOM) Wired-OR Mode disabled: ; - push-pull drivers
; (MST) Master mode off (Slave mode selected) ; (CPL) serial Clock Polarity:
; - SCK pin idles as logic low ; (CPH) Clock Phase protocol:
; - ~SS line can be tied low if only 1 slave.
#$0040,X:SPCR1
#$0004,X:SPCR1

Serial Peripheral Interface

7.6.2 Configuring an SPI Port as Slave

Example 7-2 shows how to configure an SPI port as a slave.

Example 7-2. Configuring an SPI Port as Slave

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

;* SPI slave

 

 

*

;* for serial peripheral interface (SPI) *

;* of DSP56824 chip

 

 

*

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

START

 

EQU

$0040

; Start of program

BCR

 

EQU

$FFF9

; Bus Control Register

IPR

 

EQU

$FFFB

; Interrupt Priority Register

PCC

 

EQU

$FFED

; Port C Control Register

;PCDDR

 

EQU

$FFEE

; Port C Data Direction Register [unused]

SPCR1

 

EQU

$FFE6

; SPI1 Control Register

SPDR1

 

EQU

$FFE4

; SPI1 Data Register

SPSR1

 

EQU

$FFE5

; SPI1 Status Register

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

 

 

 

;* 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:$002A

 

;

;

JSR

[unused]

; SPI0 Serial System vector

 

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.

;******************* ;* SPI Slave setup * ;******************* BFCLR

MOVEP

7-16

DSP56824 User’s Manual

 

Соседние файлы в папке DSP568xx