Using div32 to get decimal numbers

[nkwankwe]

Ladies and Gentlemen,

I have a small problem: I need to display the volume of water that is being fed by a flow transducer to PIC16F877A.The transducer outputs square pulses at 65 pulses per litre,meaning 1 pulse= 0.0154 litres.I can successfully read 65pulses/litre and display on LCD sreen.However,I need more accuracy than that,so I need to count at resolution of 1l1pulse per litre.Now the problem is the floating points.
I need help using Div32 to count and display
Thank you

Clinton

[Acetronics2]

hi, clinton

no difficulties...

suppose you won't count more than 1008 liters ( 65535 pulses ...); liters is a WORD !

1) calculate liters

liters = pulses/65 ... obvious

2) calculate decimals

Tmilliliters = ((pulses // 65) *10000)/65
centiliters = DIV32 100

here we take the pulses count remainder ( less than 1 liter ... ), multiply by 10000 and divide per 65 to get 1/10,000 liters; this number is an integer and respects the sensor conversion ratio.

then result is truncated to centiliters to keep a 0/ -1 digit ( or centiliter ) calculation precision ... and resolution.

Why centiliters ??? ... simply because sensor counts per 1.54 centiliter increment ... shown milliliters would only be virtual ... hence FALSE ! ( but our calculation is true !!!)

3 ) print result

Pulsout $FE,1 ,dec Liters,"." dec3 centiliters

here it is ...

Alain

[nkwankwe]

Thank you Alain
I'll try the coding

[nkwankwe]

I have written the code as follows below,but the output is so fast,I think its giving me millilitres rather than litres...How do I modify it





W VAR BYTE
W1 var WORD
W2 VAR WORD
W3 VAR WORD
DEFINE LCD_DREG PORTD
DEFINE LCD_DBIT 4
DEFINE LCD_RSREG PORTD
DEFINE LCD_RSBIT 1
DEFINE LCD_EREG PORTD
DEFINE LCD_EBIT 2
DEFINE LCD_BITS 4
DEFINE LCD_LINES 2
DEFINE LCD_COMMANDUS 2000
DEFINE LCD_DATAUS 50
W=0
W1=0
W3=0
PAUSE 1000
MAIN:
IF PORTC.2=1 THEN
W=1
FOR W = 0 TO 65
NEXT W
W1= W1 + (W/65)
W2= ((W1 // 65) *10000)/65
W3= DIV32 100
LCDOUT 254,1
LCDOUT DEC W1, ".", DEC W3, "L"
ENDIF
GOTO MAIN

[HenrikOlsson]

Hi,
Not sure what your trying to do but it looks like perhaps your NEXT W should be moved to between the LCDOUT and the ENDIF statements. Then, if you want to see it count on the display you'll probably need a short Pause in there a well.

/Henrik.

[Acetronics2]

Hi, Clinton

@ first your counting method is wrong ... you should count transitions ( L> H i.e.) of your output sensor.
@ second ... what's the reason of the " For w = 0 to 65 ..." loop ???
@ third ... ----------------d°----- " W1 = W1 + W/65 " ???

once that tied ... display should slow down a bit ...

Alain