Hello,
This is my first post--trying to learn how to use PICAXE and measure the temperature. I am playing with AS35--a replacement for LM35. I am using an almost exact copy of the program by Peter H Anderson:
I am also using a mercury thermometer as a "reference". Its reading is ~20.5 degC. Here is a table of the values I get on my computer screen, using different voltage sources:
Source________________Voltage (V)_____Temp.(degC)
"old" 3x1.5V batteries_______4.40__________21.9
fresh 3x1.5V batteries_______4.95_________19.9
4x1.2NiMH rechargables_____5.09__________19.5
regulated Power Supply_____5.02__________19.0
I am doing my experiments on a breadboard. I've also measured the voltage between the mid-pin of AS35 and ground--it was 0.203 V, which based on the slope from the product datasheet of 10 mV/deg corresponds to 20.2 degC, which is close to the mercury thermometer reading. Any ideas what is going on here?
Thanks
Dusko
This is my first post--trying to learn how to use PICAXE and measure the temperature. I am playing with AS35--a replacement for LM35. I am using an almost exact copy of the program by Peter H Anderson:
Code:
'based on http://www.phanderson.com/picaxe/lm34.html
'using AS35
Symbol ADVal = W0
Symbol TF_10 = W1
Symbol Whole = B5
Symbol Fract = B6
main:
ReadADC10 1,ADVal
TF_10 = ADVal * 4
TF_10 = ADVal * 8 / 10 + TF_10
TF_10 = ADVal * 8 / 100 + TF_10
Whole = TF_10 / 10
Fract = TF_10 //10
SerTxD ("T = ",#Whole, ".", #Fract,"°C",", 13, 10)
pause 1000
goto main
Source________________Voltage (V)_____Temp.(degC)
"old" 3x1.5V batteries_______4.40__________21.9
fresh 3x1.5V batteries_______4.95_________19.9
4x1.2NiMH rechargables_____5.09__________19.5
regulated Power Supply_____5.02__________19.0
I am doing my experiments on a breadboard. I've also measured the voltage between the mid-pin of AS35 and ground--it was 0.203 V, which based on the slope from the product datasheet of 10 mV/deg corresponds to 20.2 degC, which is close to the mercury thermometer reading. Any ideas what is going on here?
Thanks
Dusko