revolution counter

[lerameur]

Hi,

I want to use the COunter command to count the number of revolution I make on a pulley. The speed is variable, therefore I do not know how count will work. Also the counte command requires a period of time, like 1 second in the manual, but I do not want this, s the wheel might be turning for 5 minutes or longer.
How should I go about calculating the revolution?
I have black and white wheel encoder, with a sensor reading the analog output to digital.

ken

[mackrackit]

What else will be going on at the same time? Any idea how many times the wheel will turn and how fast?

[aratti]

You must also tell us how many pulses per turn will generate your encoder.

[lerameur]

I am making a coiling machine and will be passing the wiring into a small pulley. The pulley will have four sections, two white and two black. The sensor will be reading the encoder , there will be small led lighting the encoder from behind.
Therefore the speed I do not know, and it is not important, it will be going in one direction. I will be counting four changes for one revolution.
Here is a program I just wrote, have not tried it yet,

'Get initil value
ADCON0.2 = 1 'Start Conversion
ADCIN 1, OldOutput_Pot 'analog pin 1 (RA1) get the 8 bit result
pause 50
if OldOutput_Pot > 127 then
OldOutput_Pot =1
endif
if OldOutput_Pot < 128 then
OldOutput_Pot =0
endif

Mainloop:

ADCON0.2 = 1 'Start Conversion
ADCIN 1, Output_Pot 'analog pin 1 (RA1) get the 8 bit result
pause 50

'Calculate the distance
if Output_Pot > 127 then
Output_Pot =1
endif
if Output_Pot < 128 then
Output_Pot =0
endif

if OldOutput_Pot == Output_Pot then
goto Mainloop
endif
if OldOutput_Pot != Output_Pot then
counter = counter +1 'If oldOutput_pot is different then Output_pot
OldOutput_Pot = Output_Pot
if counter =4 then
Revolution = Revolution + 1
counter =0
endif
endif

lcdout $FE,1, "Counter:",dec counter
lcdout $FE,$C0, "Revolution:",dec Revolution
pause 150


GOTO Mainloop
end

[Jerson]

Ken

What kind of encoder are you using here? Usually an encoder would give out digital pulses. But, you seem to be using the ADC to decode it. I would suggest that you look at the possibility of counting the pulses via an interrupt. This will keep your mainline code free for other tasks. Darrell Taylor has some nice code that can kickstart you in that direction. Just search for it on this site.

Jerson

[lerameur]

My program is not outputting anything, I think it is a initilizing problem but I do not know what:
I am posting the header:
can some one help me:

' Internal Oscillation program
' A/D testing -RA.1
' LCD

'/////////////////////////
'// Define section //
'/////////////////////////

INCLUDE "modedefs.bas"
@ DEVICE pic16F88 MCLR_ON, INTRC_OSC, WDT_ON, LVP_OFF, BOD_OFF, PWRT_ON, PROTECT_OFF, CCPMX_ON
OSCCON=$60 ' use internal 4MHZ osc

ANSEL = %01000010 ' set AN1 (RA1) as analog, others to digital
ADCON1 = %00000000 ' Left justified results in 8 bits
ADCON0 = %10001001 ' Configure and turn on A/D Module
CMCON = 7 ' Disable analog comparator

'/////////////////////////
'// LCD configuration //
'/////////////////////////

DEFINE LCD_DREG PORTB ' Set LCD Data port
DEFINE LCD_DBIT 4 ' Set starting Data bit (0 or 4) if 4-bit bus

DEFINE LCD_RSREG PORTB ' Set LCD Register Select port
DEFINE LCD_RSBIT 1 ' Set LCD Register Select bit

DEFINE LCD_EREG PORTB ' Set LCD Enable port
DEFINE LCD_EBIT 0 ' Set LCD Enable bit

DEFINE LCD_BITS 4 ' Set LCD bus size (4 or 8 bits) '4 therefore put wire at 4, 5, 6 and 7 of LCD

DEFINE LCD_LINES 2 ' Set number of lines on LCD
DEFINE LCD_COMMANDUS 2500
DEFINE LCD_DATAUS 250
DEFINE CHAR_PACING 2000
pause 2000


TRISB = %00000000 ' Set PORTB to all output
TRISA = %11111111 ' Set PORTA to all input


'///////////////////////////////////////////////
'// Variable Declaration and initialization //
'///////////////////////////////////////////////
Output_Pot var byte
OldOutput_Pot var byte
Revolution var word
counter var byte

revolution = 0
Output_Pot = 0
OldOutput_Pot = 0
counter = 0
'Get initil value
ADCON0.2 = 1 'Start Conversion
ADCIN 1, OldOutput_Pot 'analog pin 1 (RA1) get the 8 bit result
pause 50
if OldOutput_Pot > 127 then
OldOutput_Pot =1
endif
if OldOutput_Pot < 128 then
OldOutput_Pot =0
endif

Mainloop: