Cirrus-logic AN74 Manual do Utilizador descarregar pdf (Página 6)

AN74

6 AN74Rev2

APPENDIX

80C51 Microcode to Interface to the CS5525/6/9

/****************************************************************************

* File: 55268051.asm

* Date: November 1, 1996

* Programmer: Keith Coffey

* Revision: 0

* Processor: 80C51

* Program entry point at routine "main".

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

* This program is designed as an example of interfacing a 80C51 to a CS5525/6/9

* Analog-to-Digital Converter. The program interfaces via Port 1 which controls the

* serial communications, calibration, and conversion signals.

****************************************************************************/

/*** Function Prototypes ***/

void initialize(void);

void reset_converter(void);

void toggle_sdo(void);

char receive_byte(void);

void transfer_byte(char);

void write_to_register(char command,char low,char mid, char high);

void read_register(char command);

void acquire_conversion(char command);

/*** Byte Memory Map Equates ***/

sfr P1 = 0x90; /*Port One*/

sfr ACC = 0xE0; /*Accumulator Register Equate*/

/*** Bit Memory Map Equates ***/

sbit CS

= 0x90; /* Chip Select, only used in four-wire mode*/

sbit SDI = 0x91; /* Serial Data In*/

sbit SDO = 0x92; /*Serial Data Out*/

sbit SCLK = 0x93; /*Serial Clock*/

/*** Global Variable ***/

char command, /*Memory Storage Variable for Command Byte */

high_byte, /*Memory Storage Variable for Most Significant Byte*/

mid_byte, /* Memory Storage Variable for Most Significant Byte*/

low_byte, /* Memory Storage Variable for Most Significant Byte*/

temp, /*General Purpose Temporary Variable*/

mode; /*Variable Stores Mode of Operation 0 = three wire, 1 = 4 wire*/

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Cirrus-logic AN74 Manual do Utilizador Página 6