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Why are you using:tempF = 3200 - ((temperature /5) * 9)Originally Posted by lerameur
instead of tempF = ( ( ( temperature / 5 ) * 9 ) + 3200 ) ?
The positive case (the only one that's working) uses the +3200, the negative cases are using the 3200-.....
What's the deal there?
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simple I need to take the difference. I believe pic basic pro can only handle unsigned numbers. So but keeking the original forula we get negative number for zero temperature. So by putting the 3200 in front , we get a positive number and add a minus sign.
for -15 degrees celcius
we have 15*100 =1500 in the euqation
=3200 - (1500/5*9) = 500
= 500/100 ------divide by hundred caus ewe multiplied by a 100 initially
=5
= -5 ----- here we just add the minus
but anyway , remember when i said my decimal values was going reverse. I was thinking and that is similar from doing 2,s compliment . so i decided to do 2,s compliment on everything..
Zerotemp: '------------- cases when zero celcius and positive Fahrenheit
temperature = ( ~ temperature ) + 1
count_per_c = ( ~ count_per_c) + 1
count_remain= ( ~count_remain) + 1
temp1 = temperature
temperature = ((( temperature >>1 ) *100)- 25) + (((count_per_c - count_remain) * 100) / count_per_c)
if tempF <= 0 then goto ZeroF
': tempf = ( ~ tempF ) + 1 ' added this
tempF = (((temperature /5) *9 ) + 3200)
lcdout $FE,1, "TempC: ", "-", dec (temperature / 100) , ".", dec2 temperature," ",$DF,"C"
lcdout $FE,$C0, "TempF: ", dec (tempF / 100) , ".", dec2 tempF ," ",$DF,"F"
goto loop
ZeroF: '---------------- cases when zero celcius and 0 Fahrenheit
tempF = 3200 - ((temperature /5) * 9)
lcdout $FE,1, "TempC: ", "-", dec (temperature / 100) , ".", dec2 temperature," ",$DF,"C"
lcdout $FE,$C0, "TempF: ", "-", dec (tempF / 100) , ".", dec2 tempF ," ",$DF,"F"
goto loop
end
Last edited by lerameur; - 30th December 2006 at 18:35.
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I thought that would work, but nope
look at his thread, last couple of posts,
seems like I am not the only one having his problem .
Last edited by lerameur; - 30th December 2006 at 20:31.
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I'm thinking that the easiest way to solve this whole mess is to add an offset to the original C value.
The 1820 will only handle temps up to +85C and has an operating range of -55 -> +125C. So, that's a total range of 180C. So, add, say 200 to the original Celsius input. You still have 3 cases to deal with (+C/F , -C/+F and -C/-F), but it might be easier to deal with this way... (and it will still work in the confines of a word value, 200 + 125 = 325 , 20000 + 12500 = 32500).
At the receiving end,
If C temp is => 200 (20000) , then subtract 200 (20000) and handle it like normal, which already works fine. +C and +F
If the C temp is => 182.22 (18222) AND < 20000....handle it for -C and +F
If the C temp is < 182.22 (18222).....handle it for -C and -F.
In the last 2 cases when you have a negative temp, I think setting a display flag and converting the temp's to a positive range, then displaying them is the way to go (flip them back over the zero, i.e. -10 = 10 with a display flag), but you're already doing that (even though it isn't working at the moment).
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thanks , I decided to take a short cut, I just realize that the equation they gave in the spec sheet is only good for positive Celsius degrees. I lokked how count_per_C and Count_Remain worked . I will try and come up with a formula for negative values with thse featuer, I will need to invert the Count remain, and flip the last two . .
anyway here is the program that works, but with only 0.5 Degrees off in the negative region.
BUT frpm 0 to -0.5 I stil get +655 C....
loop:
'23
waitfor55:
serin portb.2 , n2400 , temp : if temp <> $55 then goto waitfor55
waitforaa:
serin portb.2 , n2400 , temp : if temp <> $aa then goto waitforaa
serin portb.2, n2400, encoded11.HighBYTE : serin portb.2, n2400, encoded11.LowBYTE
serin portb.2, n2400, encoded22.HighBYTE : serin portb.2, n2400, encoded22.LowBYTE
serin portb.2, n2400, encoded33.HighBYTE : serin portb.2, n2400, encoded33.LowBYTE
serin portb.2, n2400, encoded44.HighBYTE : serin portb.2, n2400, encoded44.LowBYTE
For counter=0 TO 7 'decoding
encoded1.0[counter]=encoded11.0[counter*2] : encoded2.0[counter]=encoded22.0[counter*2]
encoded3.0[counter]=encoded33.0[counter*2] : encoded4.0[counter]=encoded44.0[counter*2]
Next counter
'41
temperature= encoded1 ' putting back together as the original temperature
For counter=0 TO 7
temperature.0[counter+8]=encoded2.0[counter+8]
Next counter
temperature.LowBYTE = encoded1
temperature.HighBYTE = encoded2
count_remain = encoded3
count_per_c = encoded4
IF temperature.11 = 1 Then goto Zerotemp
temperature = ((( temperature >> 1) *100)- 25) + (((count_per_c - count_remain) * 100) / count_per_c)
tempF = (((temperature /5) *9 ) +3200)
lcdout $FE,1, "TempC: ", "+", dec (temperature / 100) , ".", dec2 temperature," ",$DF,"C"
lcdout $FE,$C0, "TempF: ", "+", dec2 (tempF / 100) , ".", dec2 (tempF // 100)," ",$DF,"F"
goto loop
Zerotemp: '------------- cases when zero celcius and positive Fahrenheit
temperature = ( ~ temperature ) + 1
if temperature.0 =0 then
tempbit = 0
else
tempbit = 5 : tempf0 = ((temperature>>1) *10 )+5
endif
tempF = (3200 - (((tempf0*10) /5) *9 ) )
if temperature => 18 then goto ZeroF
lcdout $FE,1, "TempC: ", "-", dec (temperature >>1) , ".", dec tempbit," ",$DF,"C"
lcdout $FE,$C0, "TempF: ", "+", dec2 (tempF / 100) , ".", dec2 (tempF // 100)," ",$DF,"F"
'lcdout $FE,$C0, "T: ", dec tempf0 , ".", dec tempF ," ",$DF,"F"
goto loop
ZeroF: '---------------- cases when zero celcius and 0 Fahrenheit
tempF = ((((tempf0*10) /5) *9 ) -3200 )
lcdout $FE,1, "TempC: ", "-", dec (temperature >>1) , ".", dec tempbit," ",$DF,"C"
lcdout $FE,$C0, "TempF: ", "-", dec2 (tempF / 100) , ".", dec2 (tempF // 100)," ",$DF,"F"
goto loop
end
Last edited by lerameur; - 30th December 2006 at 23:38.
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ahhhhhhh, look on page 3 of the ds18s20 spec sheet.
0 celcius = 0000 0000 0000 0000
-0.5 celcius = 1111 1111 1111 1111
see, there is no formula for temperature in between these two, the calculation is done only ( by default with COUNT PER COUNT and COUNT REMAIN. which is obviously not good, not sure yet how I am going to fix that, working on it...
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Sounds like it's time for one of those cases where you just ignore it!
After all, how much information do you really need between 0 and -.5 C ?
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y amaybe , but the +655 is annoying, I'm almost there,
OK it stick the whole unit outside, Its giving a steady -7 C
Got rid of the +655:
added this:
IF temperature.11 = 1 Then goto Zerotemp
if temperature = 0 then goto Special
.
.
.
Special:
lcdout $FE,1, "TempC: ", dec 0 , ".", dec 0," ",$DF,"C"
lcdout $FE,$C0, "TempF: ", dec 32 , ".", dec 0," ",$DF,"F"
goto loop
Last edited by lerameur; - 31st December 2006 at 00:45.
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