Digital thermometer with LM35 and PIC16F88

Digital thermometer with LM35 and PIC16F88

  December 22, 2010    Tahmid

---

This can be a complete project on its own - a simple DIY digital thermometer with 7-segment displays and only a handful of parts - the PIC16F88, LM35 and a small number of resistors and capacitors running off a regulated 5v supply.
Temperature range - 0 to 150'C
Display type - 3 digit multiplexed 7 segment or 3 individual 7 segments
Controller: PIC16F88
Programming Language: BASIC
Compiler: mikroBASIC PRO for PIC v3.20

Complete code:

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

program DigThermo

'Programmer: Syed Tahmid Mahbub
'Compiler: mikroBASIC PRO for PIC v3.20
'Target PIC: 16F88 - 18pin DIP
'Configuration: XT OSC, PWRTE OFF, WDT OFF, RA5 - MCLR OFF, BOR OFF, LVP OFF, CP OFF, CPD OFF, DEBUG OFF, CKMNE OFF, INTEXTSW OFF

dim data7, num7 as byte
dim temperature as longword
dim digit as byte[3]

sub procedure send7 (dim value, seven as byte) 'Common Anode Displays (2 7segments)
    PORTA = 0
    select case value
           case 0 data7 = $C0
           case 1 data7 = $F9
           case 2 data7 = $A4
           case 3 data7 = $B0
           case 4 data7 = $99
           case 5 data7 = $92
           case 6 data7 = $82
           case 7 data7 = $F8
           case 8 data7 = $80
           case 9 data7 = $90
    end select
    PORTB = data7 'send temperature
    select case seven
           case 1 num7 = 2
           case 2 num7 = 4
           case 3 num7 = 8
    end select
    PORTA = num7 'choose which 7segment
end sub

sub procedure GlobInit
    TRISA = 1
    TRISB = 0
    PORTA = 0
    PORTB = 0
    ANSEL = 1 'AN0 analog
    CCP1CON = 0 'PWM off
    CMCON = 7 'Comparator off
end sub

sub procedure delay2ms
    delay_ms(2)
end sub

main:
     GlobInit
     while true
           temperature = (ADC_Read(0) * 500) >> 10
           digit[0] = temperature div 100
           digit[1] = (temperature div 10) mod 10
           digit[2] = temperature  mod 10
           send7(digit[0],1)
           delay2ms()
           send7(digit[1],2)
           delay2ms()
           send7(digit[2],3)
           delay2ms()
     wend
end.

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

Schematic:

The code can be freely used and there is no copyright restrictions or anything as such. Only credit the author where necessary.

Hex file can be freely downloaded from:
http://www.4shared.com/file/o-OBjgGB/DigThermo.html