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programming PIC16F877 to use LM35

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AUSTStudent

New Member
Hello

I want to use temperature sensor, LM35 with PIC16F877. There are many programs to connect LM35 with PIC16F877 and then show the result on LCD. I want to display the temperature reading on the Computer through parallel port, as I would be using Serial Port to connect to a mobile.

I am programming the microcontroller in PicBasic Pro. I am using one pin, AN0 to connect the output of LM35. The A/D conversion is performed. I want to have the result of conversion on PortB (or any other port) and then connect this port to computer through parallel port. The code that I have written is shown below:

********************************************************

define ADC_BITS 8

define ADC_CLOCK 3

define ADC_SAMPLEUS 50

x var byte

TRISA=255

TRISB=0

ADCON1=%10000010

pause 500

loop:

ADCIN 0,x

x = x*100 [As for room temperature, I get 0.26V, so multiplying by 100 to
get 26°C, LM35 produces 10mV/°C]

PortB = x

output PortB

pause 500

goto loop
**********************************************************

Using this code, I dont get the data on PortB. The PortB is all zeros. Can anyone plz tell me the what modification should I do in the program???I dont want to display on the LCD.

Where is the result of A/D conversion stored in PIC16F877, so that I can connect PortB to it. Plz explain in detail and that it can work.

Plz help me. Its very urgent...

Thanx a lot...

May God bless all of us...
 

ericgibbs

Well-Known Member
Most Helpful Member
hi,
You have set the ADC to 8bit = 255

With 0.26V in this gives a count of [0.26/5] *255 =13

then you are multiplying by 100 = 1300, which exceeds the 'width' of PORTB [255]

As a test just multiply by 10.. OK
 
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