Switch sensor vs. switch PIC pin

[fratello]

So the second variant it's better ?!

[Archangel]

Hi Fratello,
Well your complaint was noise interfered with data when you switch the device in /out. If you leave it "in circuit" all the time it eliminates that possibility. By using a separate input to detect a switch the noise is confined there. You might also consider using a pin that has an interrupt available, so it changes in "real time", instead of waiting for a loop to get around to it.

[fratello]

So...This is correct ?

...
If portA.7= 1 then
valoare=temperature
semn=sign
else
valoare=temperature2
semn=sign2
Endif

Gosub Selectie
Gosub Display				' B for Common CATOD;without B for Common ANOD

Goto Main

'======================================================================================       
Selectie :

IF semn ="-" then					
    DIGIT_3="-"
    else
    DIGIT_3=" "
ENDIF
 
IF valoare DIG 2 = 0 THEN
    DIGIT_2 = " "
    ELSE
    DIGIT_2 = valoare dig 2
ENDIF

    DIGIT_1 = valoare dig 1
    DIGIT_0 = valoare dig 0

RETURN
'======================================================================================       
Display:					' For Common ANOD
for i=0 to 4
    TEMP = DIGIT_3 : gosub segments
    COMMON_3 = 1 : PAUSE 1 : COMMON_3 = 0

     
    TEMP = DIGIT_2 : GOSUB segments
    COMMON_2 = 1 : PAUSE 1 : COMMON_2 = 0
   
    TEMP = DIGIT_1 : GOSUB segments
    COMMON_1 = 1 : DP = 0 : PAUSE 1 : COMMON_1 = 0 : DP = 1
  
    TEMP = DIGIT_0 : GOSUB segments
    COMMON_0 = 1 : PAUSE 1 : COMMON_0 = 0
next i
RETURN

Thanks for support !

[fratello]

One of my DS18B20 it's about 4 meters from PIC. What is the smaller value of resistor used for this sensor ? Can I try with 1k ? Thanks !

[pedja089]

I have used 15m cable and pull up resistor 680 ohms. Resistor value depends greatly on the capacity of cable. And the capacity of the cable depends on the length.

[fratello]

With 5 meters of cable from PIC to DS18B20, no need to decrease value of R (still 4k7). Thanks for support !

[fratello]

...but, in some cases, I decrease the value to 3k9...for the same lenght of cables !