ds 18s20 or ds1821

[jcleaver]

trying to read temperature have either chip cant get good reading
or maybe none
have a 877a at 20 mhz using bootloader
and have a 4.7 k pull up resistor
listing here
any help would be appreicated
have tried a number of programs to no avail



'************************************************* ***************
'* Name : UNTITLED.BAS *
'* Author : JACK CLEAVER *
'* Notice : Copyright (c) 2007 [select VIEW...EDITOR OPTIONS] *
'* : All Rights Reserved *
'* Date : 2/6/2007 *
'* Version : 1.0 *
'* Notes : *
'* : *
'************************************************* ***************
@ DEVICE pic16f877a, HS_OSC, WDT_ON, PWRT_ON, LVP_OFF, PROTECT_OFF

' Define LCD registers and bits
Define LCD_DREG PORTB ' Port for LCD Data
Define LCD_DBIT 4 ' Use upper 4 bits of Port
Define LCD_RSREG PORTB ' Port for RegisterSelect (RS) bit
Define LCD_RSBIT 3 ' Port Pin for RS bit
Define LCD_EREG PORTB ' Port for Enable (E) bit
Define LCD_EBIT 2 ' Port Pin for E bit
Define LCB_BITS 4 ' Using 4-bit bus
Define LCD_LINES 2 ' Using 2 line Display
Define LCD_COMMANDUS 2000 ' Command Delay (uS)
Define LCD_DATAUS 50 ' Data Delay (uS)

define loader_used 1


DEFINE OSC 20

'Pin 1 - Vdd (+5V)
'Pin 2 - Vss (GND)
'Pin 3 - Vo
'Pin 4 - RS to RD2 (PIC)
'Pin 5 - R/W (GND)
'Pin 6 - E to RD3 (PIC)
'Pin 11 - RD4 (PIC)
'Pin 12 - RD5 (PIC)
'Pin 13 - RD6 (PIC)
'Pin 14 - RD7 (PIC)
'DS18S20 - DQ pin to RC2(PIC), DQ pin to Vdd pin via 4.7 k r, GND pin to GND

'Define LCD_DREG PORTD
'Define LCD_DBIT 4
'Define LCD_RSREG PORTD
'Define LCD_RSBIT 2
'Define LCD_EREG PORTD
'Define LCD_EBIT 3
'Define LCD_BITS 4
'Define LCD_LINES 2

DQ var PORTC.2
temperature Var Word
count_remain Var Byte
count_per_c Var Byte

ADCON1 = 7
pause 100

Main: OWOut DQ,1,[$CC,$44]
Waitloop: OWIn DQ,4,[count_remain]
If count_remain = 0 Then Waitloop
OWOut DQ,1,[$CC,$BE]
OWIn DQ,0,[temperature.LOWBYTE,temperature.HIGHBYTE,Skip 4,count_remain,count_per_c]

temperature = (((temperature >> 1) * 100) - 25) + (((count_per_c - count_remain) * 100)/count_per_c)
Lcdout $fe,1,DEC (temperature/100),".",DEC2 temperature," C"

Pause 1000
Goto Main
End

[skimask]

trying to read temperature have either chip cant get good reading
or maybe none
have a 877a at 20 mhz using bootloader
and have a 4.7 k pull up resistor
listing here
any help would be appreicated
have tried a number of programs to no avail

Check that really long (300+ posts) thread in PBPro called SerIn SerOut Problems. In it, there's almost a complete example of running an DS1820.

[jcleaver]

ok will check
am curious doesnt owin owout not the same?

[skimask]

ok will check
am curious doesnt owin owout not the same?

I don't understand the question...

[jcleaver]

why are they using the serin serout commands
trying to display temp on a lcd
if you notice the program i copied
the temp sensor is read and written with the owout and owin command
cant understand what the serin function is doing is it sending the display to the pc

[skimask]

why are they using the serin serout commands
trying to display temp on a lcd
if you notice the program i copied
the temp sensor is read and written with the owout and owin command
cant understand what the serin function is doing is it sending the display to the pc

The other program is just an example, most likely not exactly what you need. If you read through the thread, you'll see that the program and process related to in the Serin/Serout Problem thread (in the PBPro section) is for wireless transfer of data between 2 PICs, one getting the data from a DS1820 then transmitting it, and one receiving the data and displaying it. If you read thru it all, you'll find a working model of how to read the data from the ds1820 and send it out to an LCD without worrying about the intermediate serin/serout commands.