DS1620

[Guest]

Hi everyone,

I am having some difficulty and i was hoping someone may be able to help.

I am reading a temperature using a DS1620 chip and the PIC16f877 - i am using rs232 to output the value and viewing it using hyperterminal - the output i am getting is quite riduculous - it is saying the temperature is 511???

If anyone can offer any advice this would be great beacause this problem has me stumped!!

My code is listed below:

#include <16f877.h>
#device ADC=10
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
# use delay (clock = 4000000)
#use rs232(baud=9600,xmit=PIN_C6, rcv=PIN_C7,parity=N,stream=PC)
#fuses XT,NOWDT,NOPROTECT,PUT,NOLVP
#byte PORTC = 7
#byte PORTA = 5
#bit DQ = PORTA.3
#bit CLK = PORTA.2
#bit RST = PORTA.1

void DS1620_write(unsigned int Data)
{

unsigned int i;
set_tris_a(0xF1); /*Set TRISA to Pattern 11110001 */
CLK = 1;
for (i=1; i<=8; i++)
{
DQ = (Data & 1);
CLK = 0;
CLK = 1;
Data = Data >> 1;
}
}

long DS1620_read(void)
{
long Data;
long Temp;
int i;
set_tris_a(0xF2); /*Set TRISA to Pattern 11110010 */
CLK = 1;
Data = 0;
Temp = 1;
for (i=1; i<=9; i++)
{
CLK = 0;
if (DQ == 1) Data += Temp;
Temp = Temp * 2;
CLK = 1;
}
RST = 0;
return(Data);
}

void main()
{
while(1)
{
long temperature = 0;
setup_adc_ports(NO_ANALOGS);
RST = 0;
delay_us(10);
RST = 1;
DS1620_write(0xEE);
delay_ms(750);
DS1620_write(0xAA);
temperature = DS1620_read();
delay_ms(750);
fprintf(PC, "\n\rTemperature = %ld", temperature);
delay_ms(5000);
}
}

[PCM programmer]

Have you looked at sample drivers ?
I found these quickly with http://www.google.com

Compare your code to these drivers and look for differences.
http://www.phanderson.com/printer/ds1620/ds1620.html
http://www.rentron.com/CCS_C/SERLED_C.htm
http://www.piclist.com/images/boards/temp-hum/code/lcd.c

[ckielstra]

I don't know the DS1620 but I had a quick look at your code and noticed some oddities.

[Guest]

Many Thanks- have got this up and running.