LM35 can measure temperatures from -55deg to 150deg and we need negative supply voltage for measuring this negative temperature.

This circuit eliminates the negative voltage power supply and this project can measure the negative temperature

Download the protesu file to simulate the project on your desktop

Circuit Diagram

Bascom Code

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'  www.avrprojects.info '
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$regfile = "m16def.dat"
$crystal = 1000000

Config Lcd = 16 * 2
Config Lcdpin = Pin , Db4 = Portd.4 , Db5 = Portd.5 , Db6 = Portd.6 , Db7 = Portd.7 , E = Portd.0 , Rs = Portd.1
Config Adc = Single , Prescaler = Auto , Reference = Internal

Deflcdchar 0 , 12 , 18 , 18 , 12 , 32 , 32 , 32 , 32
Deflcdchar 1 , 32 , 4 , 12 , 28 , 28 , 32 , 32 , 32
Deflcdchar 2 , 32 , 4 , 14 , 31 , 31 , 32 , 32 , 32
Deflcdchar 3 , 32 , 4 , 14 , 31 , 31 , 7 , 6 , 4
Deflcdchar 4 , 32 , 4 , 14 , 31 , 31 , 31 , 14 , 4
Deflcdchar 5 , 32 , 32 , 32 , 32 , 32 , 32 , 32 , 32

Dim A As Word
Dim B As Word
Dim C As Single
Dim D As Byte

D = 1
Start Adc

Cursor Off
Cls
Locate 2 , 1
Lcd "avrprojects.info"

Do

A = Getadc(3)
B = Getadc(4)
C = A - B
C = C / 4
Locate 1 , 1
Lcd "Temp =" ; C ; Chr(0) ; "c   "
Locate 1 , 16
Lcd Chr(d)
Waitms 500
Incr D
If D > 6 Then D = 1

Loop

End

Download

Bascom code & proteus file