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AN89

AN89Rev2 5

APPENDIX

68HC05 Microcode to Interface to the CS5525/6/9

****************************************************************************

* File: 55266805.asm

* Date: November 1, 1996

* Programmer: Keith Coffey

* Revision: 0

* Processor: 68HC05

* Program entry point at routine "main". The entry point is address $100

****************************************************************************

* This program is designed as an example of interfacing a 68HC05 to a CS5525/6/9

* ADC. The program interfaces via SPI (i.e. port D) which controls the

* serial communications, calibration, and conversion signals. Other ADC’s

* (16-bit and 20-bit) in the product family can be used.

****************************************************************************

******** Memory Map Equates

PORTA EQU $00 ; General Purpose I/O Port

DDRA EQU $04 ; Data Direction Control For Port A

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

******** Ram Memory Equates

HIGHBYTE RMB 1 ; Upper 8 bits of Conversion Register

MIDBYTE RMB 1 ; Middle 8 bits of Conversion Register

LOWBYTE RMB 1 ; Lowest 8 Bits of Conversion Register

COMMANDBYTE RMB 1 ; One byte RAM storage location

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Cirrus-logic AN89 Manual de usuario Pagina 5