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Voltmeter Code in ASM for PIC18F

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Sumihere

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Hi

I am using 10 bit ADC and the coding has been done in Assembly Language.

I need to display the input voltage (which is scaled by 2.5 ) on the LCD .

Pls suggest me on how to do this in ASM as it involves lot of floating point multiplications and all...

Thanksss
 

Sumihere said:
Hi

I am using 10 bit ADC and the coding has been done in Assembly Language.

I need to display the input voltage (which is scaled by 2.5 ) on the LCD .

Pls suggest me on how to do this in ASM as it involves lot of floating point multiplications and all...

Thanksss
Click to expand...

There are some programmers who quite assemply programming to avoid floating point manipulation. Floating point manipulation requires really a good lines of codes. BUT in your case there are ways to avoid floating point math.
Search this board.

---------- Post added at 12:27 ---------- Previous post was at 11:56 ----------

Hints,
Scales the ADC input value to 5000 and then divides by 1024. The output is a number between 0 and 5000. e.g. for a 2.5V input voltage the ADC will read 512. 512 * 5000 is 2560000 Dividing by 1024 (right shift 10 times) gives 2500. So using the fixed decimal point between the 2 and the 5 gives the final result displaying "2.500"
 

Thank you... Is it okay to give -5 V to Vref- pin in PIC18F4520..? will it damage the PIC. I am using it as bipolar ADC (-5V to +5V)
 

The ADC is based on analog reading between VRef- to VRef+. When input is at VRef-, the value returned will be 0 (zero) and when input is at VRef+, the value returned will be 1023 (2^10 - 1, i.e., 2 to the power of 10 minus 1).
 

papunblg said:
The ADC is based on analog reading between VRef- to VRef+. When input is at VRef-, the value returned will be 0 (zero) and when input is at VRef+, the value returned will be 1023 (2^10 - 1, i.e., 2 to the power of 10 minus 1).
Click to expand...

Thank you Sir...But my doubt is whether giving a giving a -ve voltage would damage the PIC by any means..
 

No no....... No -ve voltage

---------- Post added at 00:20 ---------- Previous post was at 00:19 ----------

you can't give a negative votage to any pin of the PIC.
 
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