Rounding Word Values

I am new to PICBasic and having an issue with the following portion of my code:

MAXVAL VAR Word
DIST VAR Word

MAXVAL = 32
DIST = 1 to 30

Percent=(DIST/MAXVAL)*100

The Precent value is always zero!
I suspect the "Percent" variable contains a non whole number and that is why it has no value.
Is there a way I can present this equation differently to round up or down to the nearest whole number?

I appreciate any advise.

Thank you.

Hi,
PBP only deals with integer math, truncating (not rounding) anything to the right of any decimal point. In your case the largest number you're having in the calculation is 30/32 which will come back as 0 when executed because 30/32 = 0.9375, 0.9375*100 will be treated as 0*100.

To come around this you can multiply Dist by 100 before doing the division:
Dist = Dist * 100 'Will now be 100-3000
Percent = Dist / Maxval 'Will return 93, should be 93.75

To get even better results:
Dist = Dist * 1000 'Dist will now be 1000-30000
Percent = Dist / Maxval 'Will return 937 as a representation of 93.7

Then to display the value you can do:
HSEROUT ["Result: ", Percent / 10, ".", Percent // 10, "%"], 10, 13
Which should display 93.7

If Dist was, say 11 the "true" result is (11/32)*100 = 34.375% but you'll get
11000/32 = 343, displayed as 34.3

Is that good enough or do you need it to be rounded?

/Henrik.

Thank you for the reply Henrik.

Your reply was most helpful.

Is there a way to get around truncation (round values to nearest integer) in PB PRO?

I am using LED's rather than a display as follows:

'------------------------------------------------------------------------
comp1:
If Percent > 10 Then comp2
PORTB = %00000001
Goto continue
comp2:
If Percent > 20 Then comp3
PORTB = %00000011
Goto continue
comp3:
If Percent > 30 Then comp4
PORTB = %00000111
Goto continue
comp4:
If Percent > 40 Then comp5
PORTB = %00001111
Goto continue
comp5:
If Percent > 50 Then comp6
PORTB = %00011111
Goto continue
comp6:
If Percent > 60 Then comp7
PORTB = %00111111
Goto continue
comp7:
If Percent > 70 Then comp8
PORTB = %01111111
Goto continue
comp8:
If Percent > 80 Then comp9
PORTB = %11111111
Goto continue
comp9:
If Percent > 95 Then comp10
comp10:
PORTB = %11111111
FreqOut bz, 250, 4000
pause 250
PORTB = %01111111
Low bz
pause 250

continue:

'Rest of code

'-------------------------------------------------------------------------

Again, thank you so much for your help.

Chris

Quote:

---

Dist = Dist * 1000 'Dist will now be 1000-30000
Percent = Dist / Maxval 'Will return 937 as a representation of 93.7

---

Percent = Percent + 5 'ROUND 937 UP
Percent = Percent / 10 'ANSWER 94

Norm

Thanks Norm. I think that will do the trick....

Chris, what about semplifying your code in this way:

Code:

---

AA0  var Byte  ' new variable to add.

If Percent < 95 then
AA0 = (Percent / 10) - 1
PortB = (2^AA0)-1
else
PORTB = %11111111
FreqOut bz, 250, 4000
pause 250
PORTB = %01111111
Low bz
pause 250
endif

---

will eliminate from comp1 up to label continue.

Al.

This is perfect.... I get more out of these discussions then any one book I own.

Thanks Al

Chris

btw

The circuit I am working on is for measuring the amount of salt in my water softener brine tank and displays the level on a blank switch plate via 8 LED's (see attachment). The circuit uses a Parallax PING sensor, 16F87 for the slave and 16F876 for the master. communication is via RS-485.

If anyone is interested in the specifics, I would be more than happy to share details.

Again, thanks for all the help.

Chris

Chris, I made a mistake! Sometimes I forget that PBP is not VB and in this case I have use the power sign^ improperly since PBP is not able to do power (the sign is used for Bitwise Exclusive OR). So the code I have posted will not work! To overcome this limitation I have used a lookup table so the working code is as follow:

Code:

---

AA0  var Byte  ' new variable to add.
BB0  var byte  ' new variable to add

If Percent < 95 then
AA0 = (Percent / 10) - 1
LOOKUP2 AA0,[1,3,7,15,31,63,127,255],BB0
PortB = BB0
else
PORTB = %11111111
FreqOut bz, 250, 4000
pause 250
PORTB = %01111111
Low bz
pause 250
endif

---

As you can see the code didn't change much, just removed (2^AA0)-1 and added a new variable.


Al.

Al, I appreciate the correction. I understood what you where trying to do. I too am more familiar with VB than PBP.
This definitely simplifies the overall code.
Thank you very much.

Chris