LM35DZ + Temp

I have the code below to show the temperature on LCD
The code works but i want to show on Lcd and the decimal value,
but i cann't
Like this : Temp=25.6C

Code:

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' **Setting for ADC of 16F88**

    Define ADC_BITS 10          ' 10-bit ADC used
    Define ADC_CLOCK 3          ' Internal clock used
    Define ADC_SAMPLEUS 50      ' Sample timing

    Samples var word            ' Samples
    Sample var byte            ' Sample
    Vin var Word                ' Vin is variable

    Samples=0

ADCloop:

    For Sample=1 to 10          ' Take 10 samples
    ADCIN 2, Vin                ' Read ADC ch-2 and save in Vin
                                ' (range 0-1023)
    Samples=Samples + Vin
    Pause 200                  ' Wait for LCD to startup
                                ' Seems to be appropriate.
    Next sample
   
    Vin=Samples/10              ' Mean of 10 Vin values
    Vin=(Vin*/500)>>2

    Lcdout $fe, 1              ' Clear LCD
    LCDOUT $FE,2             
    Lcdout "Temp=",Dec2 Vin,"C"

    Samples=0

    goto ADCLoop

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' **Setting for ADC of 16F88**
Define ADC_BITS 10 ' 10-bit ADC used
Define ADC_CLOCK 3 ' Internal clock used
Define ADC_SAMPLEUS 50 ' Sample timing
Samples var word:Sample var byte:Vin var Word:Samples=0
ADCloop:
For Sample=1 to 10:ADCIN 2,Vin:Samples=Samples + Vin:Pause 200 Next sample
Vin=Samples/10:Vin=(Vin*/500)>>2:Lcdout $fe, 1:LCDOUT $FE,2
Lcdout "Temp=",DEC (Vin DIG 2),DEC (Vin DIG 1),".",DEC (Vin dig 0),"C"
Samples=0:goto ADCLoop

Quote:

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Originally Posted by skimask

' **Setting for ADC of 16F88**
Define ADC_BITS 10 ' 10-bit ADC used
Define ADC_CLOCK 3 ' Internal clock used
Define ADC_SAMPLEUS 50 ' Sample timing
Samples var word:Sample var byte:Vin var Word:Samples=0
ADCloop:
For Sample=1 to 10:ADCIN 2,Vin:Samples=Samples + Vin:Pause 200 Next sample
Vin=Samples/10:Vin=(Vin*/500)>>2:Lcdout $fe, 1:LCDOUT $FE,2
Lcdout "Temp=",DEC (Vin DIG 2),DEC (Vin DIG 1),".",DEC (Vin dig 0),"C"
Samples=0:goto ADCLoop

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It's not show corect.
I try the code below and work but the decimal change every 0.5C
How change to have resolution every 0.1C

Code:

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        Quanta                Con        1250 

    ADCIN 2,AD_Result                        ' Place the conversion of channel0 into AD_RESULT   
        Volts = (AD_RESULT*10) */ Quanta
        Lcdout $FE,1
    Lcdout "Temp : ",dec1 Volts DIG 3,DEC1 Volts DIG 2,".",DEC1 Volts DIG 1,DEC1 Volts DIG 0,"C"
                                ' So as to display like "23.4C"

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Quote:

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Originally Posted by savnik

It's not show corect.
I try the code below and work but the decimal change every 0.5C
How change to have resolution every 0.1C

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Ok, forget all the math and displaying for the moment...

What is the output on the LCD if you only read the A/D converter with the LM35DZ connected... no averaging, no multiple samples, no nothing, just one saple, one display...pause, one sample, one display, and so on...
Get a good reading that seems to make sense, then we can work on displaying it correctly...

The LM35 puts out 10mv/°C.
1 "Step" of 10-bit A/D is 4.88mv.
So each "step" equals ~0.5°C

If you use a Vref of 2.5V, you could get 0.25°C resolution.

With an op-amp you might get down to 0.1°C res. if you don't need the full +150°C range.

Or you could use a DS18B20. That'll get 0.0625°C.
<br>

Quote:

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Originally Posted by Darrel Taylor

The LM35 puts out 10mv/°C.
1 "Step" of 10-bit A/D is 4.88mv.
So each "step" equals ~0.5°C

If you use a Vref of 2.5V, you could get 0.25°C resolution.

With an op-amp you might get down to 0.1°C res. if you don't need the full +150°C range.

Or you could use a DS18B20. That'll get 0.0625°C.
<br>

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Good call DT! I thought the datasheet said 1mv/C.

what happened in your first example?

If you used DEC3, what was the results...apart that the decimal point was missing?

Now, i have set ADCON1 register to produce Right Justified results (ADCON1.7=1) and used this

Code:

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ADCloop:
    For Sample=1 to 10          ' Take 10 samples
        ADCIN 0, Vin                ' Read ADC ch-2 and save in Vin
                                    ' (range 0-1023)
        Samples=Samples + Vin
        Next sample
   
    Vin=Samples/10              ' Mean of 10 Vin values
    Vin=(Vin*/500)>>2

    Lcdout $fe, 1              ' Clear LCD
    LCDOUT $FE,2             
    Lcdout "Temp=",DEC Vin DIG 2, DEC Vin DIG 1,".", DEC1 VIN,"C"

    Samples=0
    PAUSE 100
    goto ADCLoop

---

it worked.

EDIT: ARGH!

Quote:

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Originally Posted by Darrel Taylor

The LM35 puts out 10mv/°C.
1 "Step" of 10-bit A/D is 4.88mv.
So each "step" equals ~0.5°C

If you use a Vref of 2.5V, you could get 0.25°C resolution.

With an op-amp you might get down to 0.1°C res. if you don't need the full +150°C range.

Or you could use a DS18B20. That'll get 0.0625°C.
<br>

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Thank you for answer
I have use this schematic

Quote:

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Originally Posted by mister_e

what happened in your first example?

If you used DEC3, what was the results...apart that the decimal point was missing?

Now, i have set ADCON1 register to produce Right Justified results (ADCON1.7=1) and used this

Code:

---

ADCloop:
    For Sample=1 to 10          ' Take 10 samples
        ADCIN 0, Vin                ' Read ADC ch-2 and save in Vin
                                    ' (range 0-1023)
        Samples=Samples + Vin
        Next sample
   
    Vin=Samples/10              ' Mean of 10 Vin values
    Vin=(Vin*/500)>>2

    Lcdout $fe, 1              ' Clear LCD
    LCDOUT $FE,2             
    Lcdout "Temp=",DEC Vin DIG 2, DEC Vin DIG 1,".", DEC1 VIN,"C"

    Samples=0
    PAUSE 100
    goto ADCLoop

---

it worked.

EDIT: ARGH!

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The LCD show Temp=02.5C
but the right is Temp=25C

Quote:

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Originally Posted by skimask

Ok, forget all the math and displaying for the moment...

What is the output on the LCD if you only read the A/D converter with the LM35DZ connected... no averaging, no multiple samples, no nothing, just one saple, one display...pause, one sample, one display, and so on...
Get a good reading that seems to make sense, then we can work on displaying it correctly...

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The output on the LCD is 44-46 (Vin = 44~46)
The temperature is about 22C in room

I change to :

Code:

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ADCloop:

    ADCIN 2,Vin
    Pause 200
    Vin=(Vin* 10)/2
    Lcdout $fe, 1
    LCDOUT $FE,2
    Lcdout "Temp=",DEC (Vin DIG 2),DEC (Vin DIG 1),".",DEC (Vin dig 0),"C"                                 
    goto ADCLoop

---

and believe is right
The LCD now show : Temp=22.5C

Quote:

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Originally Posted by Darrel Taylor

The LM35 puts out 10mv/°C.
1 "Step" of 10-bit A/D is 4.88mv.
So each "step" equals ~0.5°C

If you use a Vref of 2.5V, you could get 0.25°C resolution.

With an op-amp you might get down to 0.1°C res. if you don't need the full +150°C range.

Or you could use a DS18B20. That'll get 0.0625°C.
<br>

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I want to measure from 0 - 100C

Quote:

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Originally Posted by savnik

I want to measure from 0 - 100C

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So what's the problem? The answer has already been given to you twice in the posts above, even if other parts of the code were wrong, if you'd take a few seconds to look over the display part of the above code, you'd find your answer, between that and the PBP manual, which does describe what you need...

Quote:

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Originally Posted by savnik

I want to measure from 0 - 100C

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I answer , don't ask