Overview
The DS2430 1-W 256-bit EEPROM might be used as a silicon serial number to uniquely identify a product and also to store site dependent data and calibration data.
A more complete discussion in the context of a PIC12C509 appears elsewhere.
// Program 2430_1.C (CCS PCM - PIC16F84)
//
// Illustrates use of DS2430A 1-W 256 bit EEPROM.
//
// Writes 8 bytes to DS2430A beginning at address 0x06 and then
// reads them back and displays them on serial LCD on RA.0.
//
// 16F84 DS2430A
// RB.0 (term 6) ------------------------------ DQ (term 2)
//
// copyright, P. H. Anderson, Baltimore, MD, Apr, '99
#case
#include <16F84.h>
#include <defs_f84.h>
#define TxData 0 // RA.0 for LCD display
void write_ds2430(int sensor, int adr, int *buff, int num_vals);
void read_ds2430(int sensor, int adr, int *buff, int num_vals);
// 1-wire prototypes
void _1w_init(int sensor);
int _1w_in_byte(int sensor);
void _1w_out_byte(int d, int sensor);
void _1w_pin_hi(int sensor);
void _1w_pin_low(int sensor);
void _1w_strong_pull_up(int sensor); // not used in this routine
// delay routines
void delay_ms(long t);
void delay_10us(int t);
// LCD routines
void lcd_init(void);
void out_RAM_str(int *s);
void lcd_hex_byte(int val);
void lcd_dec_byte(int val, int digits);
int num_to_char(int val);
void lcd_char(int ch);
void lcd_new_line(void);
void main(void)
{
int d[8]={0x00, 0x02, 0x04, 0x06, 0x08, 0x0a, 0x0c, 0x0e};
// data to write to EEPROM
int buff[8], n;
lcd_init();
write_ds2430(0, 6, d, 8);
// sensor 0, adr 6, array d, 8 bytes
read_ds2430(0, 6, buff, 8);
// sensor 0, adr 6, array buff, 8 bytes
for(n=0; n<8; n++)
{
if ((!(n%4)) && (n!=0)) // 4 bytes to a line
{
lcd_new_line();
}
lcd_hex_byte(buff[n]);
lcd_char(' ');
}
lcd_new_line();
}
void write_ds2430(int sensor, int adr, int *buff, int num_vals)
// write num_vals in array buff beginning at address adr
{
int n;
_1w_init(sensor);
_1w_out_byte(0xcc, sensor); // skip ROM
_1w_out_byte(0xf0, sensor); // read memory into scratch pad
_1w_init(sensor);
_1w_out_byte(0xcc, sensor); // skip ROM
_1w_out_byte(0x0f, sensor); // write scratch pad
_1w_out_byte(adr, sensor); // starting address
for(n=0; n<num_vals; n++)
{
_1w_out_byte(buff[n], sensor);
}
_1w_init(sensor);
_1w_out_byte(0xcc, sensor); // skip ROM
_1w_out_byte(0x55, sensor); // copy scratch pad
_1w_out_byte(0xa5, sensor); // validation key
_1w_strong_pull_up(sensor); // while programming
}
void read_ds2430(int sensor, int adr, int *buff, int num_vals)
// reads num_vals bytes into array buff beginning at address adr
{
int n;
_1w_init(sensor);
_1w_out_byte(0xcc, sensor); // skip ROM
_1w_out_byte(0xf0, sensor); // read memory into scratch pad
_1w_out_byte(adr, sensor);
for(n=0; n<num_vals; n++)
{
buff[n]=_1w_in_byte(sensor);
}
}
// The following are standard 1-Wire routines.
void _1w_init(int sensor)
{
_1w_pin_hi(sensor);
_1w_pin_low(sensor);
delay_10us(50);
_1w_pin_hi(sensor);
delay_10us(50);
}
int _1w_in_byte(int sensor)
{
int n, i_byte, temp, mask;
mask = 0xff & (~(0x01<<sensor));
for (n=0; n<8; n++)
{
PORTB=0x00;
TRISB=mask;
TRISB=0xff;
#asm
CLRWDT
NOP
NOP
#endasm
temp=PORTB;
if (temp & ~mask)
{
i_byte=(i_byte>>1) | 0x80; // least sig bit first
}
else
{
i_byte=i_byte >> 1;
}
delay_10us(6);
}
return(i_byte);
}
void _1w_out_byte(int d, int sensor)
{
int n, mask;
mask = 0xff & (~(0x01<<sensor));
for(n=0; n<8; n++)
{
if (d&0x01)
{
PORTB=0;
TRISB=mask; // momentary low
TRISB=0xff;
delay_10us(6);
}
else
{
PORTB=0;
TRISB=mask;
delay_10us(6);
TRISB=0xff;
}
d=d>>1;
}
}
void _1w_pin_hi(int sensor)
{
TRISB = 0xff;
}
void _1w_pin_low(int sensor)
{
PORTB = 0x00;
TRISB = 0xff & (~(0x01 << sensor));
}
void _1w_strong_pull_up(int sensor) // bring DQ to strong +5VDC
{
PORTB = 0x01 << sensor;
TRISB = 0xff & (~(0x01 << sensor));
delay_ms(250);
TRISB = 0xff;
}
// delay routines
void delay_10us(int t)
{
#asm
BCF STATUS, RP0
DELAY_10US_1:
CLRWDT
NOP
NOP
NOP
NOP
NOP
NOP
DECFSZ t, F
GOTO DELAY_10US_1
#endasm
}
void delay_ms(long t) // delays t millisecs
{
do
{
delay_10us(100);
} while(--t);
}
// LCD routines
int num_to_char(int val) // converts val to hex character
{
int ch;
if (val < 10)
{
ch=val+'0';
}
else
{
val=val-10;
ch=val + 'A';
}
return(ch);
}
void lcd_char(int ch) // serial output to PIC-n-LCD, 9600 baud
{
int n, dly;
// start bit + 8 data bits
#asm
BCF STATUS, RP0
MOVLW 9
MOVWF n
BCF STATUS, C
LCD_CHAR_1:
BTFSS STATUS, C
BSF PORTA, TxData
BTFSC STATUS, C
BCF PORTA, TxData
MOVLW 32
MOVWF dly
LCD_CHAR_2:
DECFSZ dly, F
GOTO LCD_CHAR_2
RRF ch, F
DECFSZ n, F
GOTO LCD_CHAR_1
BCF PORTA, TxData
CLRWDT
MOVLW 96
MOVWF dly
LCD_CHAR_3:
DECFSZ dly, F
GOTO LCD_CHAR_3
CLRWDT
#endasm
}
void lcd_init(void) // sets TxData in idle state and resets PIC-n-LCD
{
#asm
BCF STATUS, RP0
BCF PORTA, TxData
BSF STATUS, RP0
BCF TRISA, TxData
BCF STATUS, RP0
#endasm
lcd_char(0x0c);
delay_ms(250);
}
void lcd_new_line(void) // outputs 0x0d, 0x0a
{
lcd_char(0x0d);
delay_ms(10); // give the PIC-n-LCD time to perform the
lcd_char(0x0a); // new line function
delay_ms(10);
}
void out_RAM_str(int s)
{
while(*s)
{
lcd_char(*s);
++s;
}
}
void lcd_hex_byte(int val) // displays val in hex format
{
int ch;
ch = num_to_char((val>>4) & 0x0f);
lcd_char(ch);
ch = num_to_char(val&0x0f);
lcd_char(ch);
}
void lcd_dec_byte(int val, int digits)
// displays byte in decimal as either 1, 2 or 3 digits
{
int d;
int ch;
if (digits == 3)
{
d=val/100;
ch=num_to_char(d);
lcd_char(ch);
}
if (digits >1) // take the two lowest digits
{
val=val%100;
d=val/10;
ch=num_to_char(d);
lcd_char(ch);
}
if (digits == 1) // take the least significant digit
{
val = val%100;
}
d=val % 10;
ch=num_to_char(d);
lcd_char(ch);
}