Cirrus-logic AN131 Bedienungsanleitung PDF herunterladen (Seite 6)

AN131

6 AN131REV2

6. APPENDIX: 68HC05 MICROCODE TO INTERFACE TO THE CS5521/22/23/24/28

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

;* File: 55226805.ASM

;* Date: September 23, 1998

;* Revision:0

;* Processor:68HC05

;* Program entry point at routine ’main’. Entry point address is $100

;* This program is an example on how to interface a 68HC05 Microcontroller

;* to a CS5521/22/23/24/28 ADC. The program interfaces via the SPI port (Port D)

;* on the microcontroller, which controls the serial communications,

;* calibration, and conversion cycles.

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

;*** Memory Map Equates ***

PORTA EQU $00 ;General Purpose I/O Port

DDRA EQU $04 ;Data Direction Control for Port A

PORTD EQU $03 ;Port D Direct Pin Access (Input)

SPCR EQU $0A ;Serial Peripheral Control Register

SPSR EQU $0B ;Serial Peripheral Status Register

SPDR EQU $0C ;Serial Peripheral Data I/O Register

SPIF EQU 7 ;Serial Peripheral Data Transfer Flag

;*** RAM Values ***

ORG $50

HIGHBYTE RMB 1 ;Upper 8 bits of Conversion Register

MIDBYTE RMB 1 ;Middle 8 bits of Conversion Register

LOWBYTE RMB 1 ;Lower 8 bits of Conversion Register

COMMAND RMB 1 ;Command Byte storage location

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

;* Program Code

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

ORG $100

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

;* Routine - main

;* Input - none

;* Output - none

;* This is the entry point and the main loop of the program.

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

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Cirrus-logic AN131 Bedienungsanleitung Seite 6