DS1620. Displaying the Floating Point with BS2

C.Moher

I am using the debug command to display a binary word from a DS1620 converted into·a decimal format. Displays temperature fine but truncates the number, hacking off the tenths decimal. The DS1620 is capable of displaying to a +/-·0.5 C·resolution.·I'd like to see that displayed also. How the DS1620 works is that it sends the number X 2 to the stamp. For example if the temperature read is 22.5 degrees C, it sends the number 45 out (in binary , lsb first) to the stamp. So if you are happy with just an integer measurement, you divide the number by 2 and display it via the debug command. Eg:
degC = x / 2
DEBUG ? degC
Again you get just the integer part...in the above example 22 degrees C...How do I get the decimal part ? Thanks in advance for your help.

Robert Kubichek

Would multiplying by 10 to shift the decimal, then divide by 2, and just shifting the decimal back work?


bob

Tracy Allen

degC = x * 5   ' this is in units of 0.1 degC, but resolution of 0.5 degC, 
                     ' e.g. x=45 --> degC=225
                     ' and  ...,210, 215, 220, 225,... units of 0.5 degC
DEBUG degC/10, ".", DEC1 degC   ' displays with tenths, e.g. 21.0, 21.5, 22.0, 22.5 etc.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Tracy Allen
www.emesystems.com

C.Moher

Not sure what you mean by "just shifting the decimal back" ....how ?? Dividing by 10 again ?? I'm not sure, I can try it but what I have gathered from the research I have done, its not an easy task apparently so I don't think something that simple will do it. I'll give it a try though.

C.Moher

Nope sorry Tracy. That's giving a square.0 repeatedly. Here's what my code looks like now with that in it:
x VAR Byte ' General purpose variable, Byte.
degC VAR Byte ' Variable to hold degrees Celsius.
' Note: DS1620 has been preprogrammed for mode 2.
OUTS=%0000000000000000 ' Define the initial state of all pins,
'FEDCBA9876543210
DIRS=%1111111111111111 ' as low outputs.
FREQOUT 0, 1000, 2000 ' Beep to signal that it is running.
HIGH 13 ' Select the DS1620.
SHIFTOUT 15, 14, LSBFIRST, [noparse][[/noparse]238] ' Send the "start conversions" command.
LOW 13 ' Do the command.
DO ' Going to display once per second.
HIGH 13 ' Select the DS1620.
SHIFTOUT 15, 14, LSBFIRST, [noparse][[/noparse]170] ' Send the "get data" command.
SHIFTIN 15, 14, LSBPRE, [noparse][[/noparse]x] ' Get the data.
LOW 13 ' End the command.
degC = x * 5 ' this is in units of 0.1 degC, but resolution of 0.5 degC,
' e.g. x=45 --> degC=225
' and ...,210, 215, 220, 225,... units of 0.5 degC
DEBUG degC/10, ".", DEC1 degC ' displays with tenths, e.g. 21.0, 21.5, 22.0, 22.5 etc.
PAUSE 1000 ' 1 second pause.
LOOP ' Read & display temperature again.

C.Moher

ye haw... Tracy your code works fine but you were missing the "DEC' in front of the first degC....should be:

DEBUG DEC degC/10, ".", DEC1 degC

Thanks for your help. I'll spend the rest of the week answering the ? "but why"