ds18s20 reads incorectly

[skimask]

the osc is correct dont know why it did not show caps
tried going with 4 still read low
? what changes in math
TEMP = ((TEMP*9/5)+32 ) is what i am using
thanks for the inputs

have not found any samples using owin with this chip

Ok, try this:

@ DEVICE pic16F877A, HS_OSC
@ DEVICE pic16F877A, WDT_ON
@ DEVICE pic16F877A, PWRT_ON
@ DEVICE pic16F877A, BOD_ON
@ DEVICE pic16F877A, MCLR_on
@ DEVICE pic16F877A, LVP_OFF
@ DEVICE pic16F877A, CPD_OFF
@ DEVICE pic16F877A, PROTECT_OFF
define osc 20
define loader_used 1
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_lines 2
define lcd_bits 4
define lcd_commandus 2000
define lcd_dataus 50
command var byte:i var byte:temp var word:dq var porta.5:dq_dir var trisa.5
adcon1=255:porta=255:portb=0:trisa=255:trisb=0:cmcon=7
Lcdout $fe,1,"Temp in degrees C"
mainloop:	Gosub init1820:command=$cc:Gosub write1820:command=$44
Gosub write1820:Pause 2000:Gosub init1820:command=$cc:Gosub write1820
Pause 2000:command=$be:Gosub write1820:Gosub read1820:TEMP=((TEMP*9/5)+32)
Lcdout $fe,1,dec(temp>>1),".",dec(temp.0*5)," degrees C":Goto mainloop
init1820:	Low DQ:Pauseus 500:DQ_DIR=1:Pauseus 100
If DQ=1 Then Lcdout $fe,1,"DS1820 not present":Pause 500:Goto mainloop
Pauseus 400:Return
write1820:	For i=0 to 7:low dq
If command.0[temp] = 0 Then
	Pauseus 60:DQ_DIR = 1
Else
	@ nop
	DQ_DIR = 1:Pauseus 60
Endif
Next i:Return
read1820:	For i=0 to 15:low dq
		@ nop
		dq_dir=1:temp.0[i]=1:if dq=0 then temp.0[i]=0
		pauseus60:next i:return
End

[jcleaver]

Tried This And Get Better Reading Only 6 Deg Low

However It Does Not Respond To Any Temperature Changes

Thanks

[skimask]

Tried This And Get Better Reading Only 6 Deg Low
However It Does Not Respond To Any Temperature Changes
Thanks

Ok, what DOES it put out for a temperature?

What happens if you heat it up, read the temperature, shut it off, put it in the freezer for a few minutes, take it out, power it up and read the temp right away?

[jcleaver]

Read 65.xxxx

Does Not Update Hold Sensor And Nothing Changes

Reloaded Several Programs And They Work However Still Get Low Tmp Reading

Dont Think Its A Hardware Problem Because It Works Perfectly In Mikroe

Guess I Could That But Have Better Luck With Pbp As For As Adding My Stuff

[skimask]

Read 65.xxxx
Does Not Update Hold Sensor And Nothing Changes
Reloaded Several Programs And They Work However Still Get Low Tmp Reading
Dont Think Its A Hardware Problem Because It Works Perfectly In Mikroe
Guess I Could That But Have Better Luck With Pbp As For As Adding My Stuff

65.xxx
Hmmm....maybe 65.535? 65.535 F? 65.535 C ?
Ever think that maybe your input was all 1's? And that it might've just been coincidence that your temp's are about 30 degrees low depending on the temp of the room?

Try this, might help...
http://www.picbasic.co.uk/forum/showthread.php?t=561

AND:

[Acetronics2]

Hi, Cleaver

I suppose you work on an easyPic 4 or 5 ...

try this with sensor connected to PORTE2 and Pullup on porta.0 and 1.

After power on, type of sensor and ID is displayed.

press RA0 Button ( active low ! ) and you turn to thermo mode ( thermostat, in fact , see RA0 and RA.1 use ... )

Alain

PS : Fully PbP Written Program...

[manwolf]

jcleaver

Here is a couple of files for you to play with.

pbptc.txt is your program that correctly displays the temp C and changes when the temp changes. You will need to change the LCD port, I use an easypic5 and you are using a different port.

I also have a program for MikroB attached, again it is for the ep5 board.

Take a few minutes and look at how the temp is being read in both. Once you figure that out you will see where the problem is.

BTW the formula is from the DS18S20 datasheet.





In your Mikro file did you notice that the temp was calculated before it is converted?

if j2 = $FF then
tmp_sign = "-" ' temperature sign
j1= j1 or $FF ' complement of two
j1= j1 + $01
else
tmp_sign = "+"
end if
j2 = (j1 and $01) * 5 ' Get decimal value
j1 = j1 >> 1 ' Get temp value
j1 = ((j1*9/5)+32) 'Convert C to F

And in your PBP file nothing is calculated until after the conversion.

TEMP = ((TEMP*9/5)+32 )
Lcdout $fe, 1, dec (temp >> 1),".",dec(temp.0 * 5)," degrees C"

Good Luck!

Acetronics: May I play around with the thermostat program you posted?