Help with ADC data

poorieuser

Ok so I'm doing some data logging use the BS2 stamp and an 8 bit ADC. Basically I need to program to bring in the data from the ADC that tells me Potential of a battery pack in a circuit. When it reaches a certain point I need the program to stop running.

Right now the program reads in the data from the ADC fine. It gives me an 8bit binary value. I can convert that outside the program and figure out the voltage easily. However I need the program to be able to convert the 8bit binary value into a decimal value so I can use a DO UNTIL loop and have it end when the potential reaches 2 volts. Otherwise the test destroys the batteries as it runs indefinitely.

Any help will be greatly appreciated.

Martin Hebel

Assuming the ADC is spanned for 0 to 5V you can use the general formula of: value * output / input

volt = binary value * 50 / 255

This will give you a reading of 0 to 50 tenths of a volt, so 2V would be 20.

-Martin

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SelmaWare Solutions - StampPlot GUI for controllers, XBee and Propeller Application Boards

Southern Illinois University Carbondale, Electronic Systems Technologies

poorieuser

Don't you have to convert the binary value to a decimal value first? Thats how I've gotten voltage.

Basically the code reads a binary value in from the adc to a variable adcBits.

adcBits is a 8bit binary value originally but I need to convert it to a decimal value, at least, from what I understand.

Franklin

All numbers are binary to the computer and are different to us.

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- Stephen

poorieuser

ok so uh if i multiply 10000011 * 5/256 or 131 * 5/256 its going to give me the same thing?

Basically if I have, when adcBits is an 8bit binary...

DO UNTIL (adcBits * 5/256 <2)
blah blah
blah
LOOP

It should loop until my circuit dips below two volts?