> Does anyone have any suggestions?

Skip floating point. Use an integer instead.

Why do you need the value in HyperTerm ? Is it for
test or debugging ? Is it important that the value
is a correct interpretation of the actual voltage ?
Would not the raw value from the ADC do ?

Take "3.0018" as an example. Ad say MULTIPLIER =3D 4.

lWhole=3D(long)((float)fInput); will give an integer with value 3, not ?

ulPart=3D(long)((float)fInput*MULTIPLIER)-lWhole*MULTIPLIER;
That will give the part after the ".", that is "0018", still
as an integer. So 30018 - 3000 =3D 18.

You do now that leading zeros are realy of "no value", right ?

So "0018" is equal to "18".

Can not printf() take a float and do the conversion on the fly ?

You probably need to use strings if you are going to split
the float that way to preserve the leading zero.

Or if printf has some params to specify a fixed length equal
to MULTIPLIER and with zero fill to the left...

Jan-Erik.



rchadwic wrote 2011-11-15 23:38:
> I am using MPLab C18 Compiler V3.38 to program an 18C4550; presently tryi=
ng
> to use the ADC to convert voltage on a potentiometer and send it on a ser=
ial
> UART) interface to be displayed on Hyperterminal.
> I am using the code suggested in
> http://support2.microchip....aspx?ID=3DSQ6UJ9A003PQX
> <http://support2.microchip.com/KBSearch/KB_StdProb.aspx?ID=3DSQ6UJ9A003PQ=
X>
> to convert a floating point number (ADC voltage), using printf to send th=
e
> result to the serial output.  Code is reproduced below.
> I find that the code does not reproduce the ASCII value correctly if the
> floating point number leads with a zero behind the decimal point.
> Example:
> Floating point number	2.9984		ASCII	2.99	(good)
> 			3.0018		ASCII	3.18	(bad)
> 			3.095		ASCII 	3.95	(bad)
> 			3.104		ASCII	3.10	(good)
> It looks like the code somehow is dropping leading zeros, but I can not s=
ee
> how or see a way to make it stop doing this.
> Does anyone have any suggestions?  Thank you.
>
> CODE:  (copied from Microchip note)
> float fInput=3D344.9876; // Pick a number
> long lWhole=3D0; // Stores digits left of decimal
> unsigned long ulPart=3D0; // Stores digits right of decimal
>
> #define MULTIPLIER 100 //(use 1 for no decimals, 10 for 1 place,
> // 100 for 2 places, etc)
>
> #include<stdio.h>
> #include<p18f242.h>  // choose your device as needed
>
> void main(void)
> {
> // Set up the USART for output (not required, but since printf sends to t=
he
> USART, it makes the output readable in the output window)
> SPBRG=3D15;
> TXSTA=3D0x24;
> RCSTA=3D0x90;
>
>
> //Convert number from float to fixed point for display.
> //The number is converted to two parts.
> lWhole=3D(long)((float)fInput);
> ulPart=3D(long)((float)fInput*MULTIPLIER)-lWhole*MULTIPLIER;
>
> printf((far char *)"The floating point number is: %li.%li\n",lWhole,ulPar=
t);
> while(1); // wait forever
> }
>
>
>
>
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