Problem in Tension/compression

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- 11th July 2007, 12:15
precision

Problem in Tension/compression

This is my code for length measurements for fatigue testing machine with PEAK-HOLD.
I use 1000 PPR encoder with CH A and CH B for up/down, code working well when machine working in compression.
but problem is when machine work in tension side, encoder count 65535 below 00

i want this sequence

<<---------- 00 --------->>
Tension Compression
6-5-4-3-2-1-0-1-2-3-4-5-6

chip 16f88

Code:

DEFINE OSC 20 INCLUDE "MODEDEFS.BAS" INCLUDE "MYLCD.BAS" ANSEL = 0 'SELECT ANALOG INPUTS 0 = NONE AND ALL DIGITAL ADCON0 = 0 'AD MODULE OFF & CONSUMES NO CURRENT CMCON = 7 'COMPARATORS OFF TRISA = %00000 TRISB = %00000011 ' INT0 = ENCODER CH. A ' PORTB.1 = ENCODER CH. B W0 VAR WORD B1 var word W0 = 0 B1 = 0 PAUSE 500 '------------------------------------------------------------------------- INCLUDE "DT_INTS-14.bas" ; Base Interrupt System INCLUDE "ReEnterPBP.bas" ; Include if using PBP interrupts ASM INT_LIST macro ; IntSource, Label, Type, ResetFlag? INT_Handler INT_INT, _ToggleLED1, PBP, yes endm INT_CREATE ; Creates the interrupt processor ENDASM OPTION_REG.6 = 0 ; 1 = Interrupt on rising edge of INT pin ; 0 = Interrupt on falling edge of INT pin @ INT_ENABLE INT_INT ; enable external (INT) interrupts '------------------------------------------------------------------------- LOOP: if W0 > B1 then B1 = W0 ' (Peak-Hold), Hold the last value of W0 in B1 LCDOUT $FE,1 LCDOUT "Length = ", dec5 w0, " mm" lcdout $FE, $C0 lcdout "Peak- Value ",dec5 B1, " mm" pause 500 GOTO LOOP ToggleLED1: if PORTB.1 = 0 then W0 = W0+1 else w0 = w0-1 IF (W0 < 0) THEN W0 = 65535 + 1 endif ENDIF @ INT_RETURN
- 11th July 2007, 12:25
skimask

Code:

W0 VAR WORD W0 = 65535 + 1

You have a word variable (16 bits)...
What's happens when you do the above math?
%1111111111111111 + %0000000000000001 = %10000000000000000
17 bits doesn't fit in a 16 bit variable.

An idea...divide all your numbers in half and use 32767 ($7FFF) as your new 'ZERO' point, change the LCD out routine to show that.
- 11th July 2007, 13:18
precision

When counts cross 65535, number will be 00000 and counts again upto 65535

but when i code
if W0 < 0 then W0 = 65535 + 1

after this counter will 00000 and hang on 00001

.
- 11th July 2007, 13:45
skimask

Quote:

Originally Posted by precision

When counts cross 65535, number will be 00000 and counts again upto 65535
but when i code
if W0 < 0 then W0 = 65535 + 1
after this counter will 00000 and hang on 00001
.

That's my point...
W0 cannot be less than 'ZERO' with PBP...
PBP does not natively handle negative numbers using normal math routines. Yes there are a few commands that can handle signed integers, but not in the way you're looking to handle them. There are no 'minus' signs
You must figure out your own method to handle those negative numbers.
- 12th July 2007, 01:36
Darrel Taylor

precision,

Give this a try.

Code:

DEFINE OSC 20 INCLUDE "MODEDEFS.BAS" INCLUDE "MYLCD.BAS" ANSEL = 0 'SELECT ANALOG INPUTS 0 = NONE AND ALL DIGITAL ADCON0 = 0 'AD MODULE OFF & CONSUMES NO CURRENT CMCON = 7 'COMPARATORS OFF TRISA = %00000 TRISB = %00000011 ' INT0 = ENCODER CH. A ' PORTB.1 = ENCODER CH. B W0 VAR WORD LastW0 VAR WORD B1 var word W0 = 0 B1 = 0 PAUSE 500 '------------------------------------------------------------------------- INCLUDE "DT_INTS-14.bas" ; Base Interrupt System INCLUDE "ReEnterPBP.bas" ; Include if using PBP interrupts ASM INT_LIST macro ; IntSource, Label, Type, ResetFlag? INT_Handler INT_INT, _ToggleLED1, PBP, yes endm INT_CREATE ; Creates the interrupt processor ENDASM OPTION_REG.6 = 0 ; 1 = Interrupt on rising edge of INT pin ; 0 = Interrupt on falling edge of INT pin @ INT_ENABLE INT_INT ; enable external (INT) interrupts '------------------------------------------------------------------------- LCDOUT $FE,1 LOOP: IF W0 <> LastW0 then LastW0 = W0 ' (Peak-Hold), Hold the last value of W0 in B1 if ABS(LastW0) > ABS(B1) then B1 = LastW0 LCDOUT $FE,2 LCDOUT "Length = ", Sdec LastW0, " mm " lcdout $FE, $C0 lcdout "Peak- Value ",Sdec B1, " mm " ENDIF GOTO LOOP ToggleLED1: if PORTB.1 = 0 then W0 = W0+1 else w0 = w0-1 ENDIF @ INT_RETURN

The range will be +/-32767.

Added: Modified slightly to eliminate changes while displaying.

Modified again to simplify. ABS() works for both pos and neg numbers. Doh!
It also fixes a problem if it moves slightly negative before going positive.
I'll get it right one of these times :)
- 12th July 2007, 02:44
Darrel Taylor

Just posting this for an email notification that I changed the program above.

In case you're already trying it.
- 12th July 2007, 05:05
precision

Quote:

Originally Posted by Darrel Taylor

Just posting this for an email notification that I changed the program above.

In case you're already trying it.
 

Sir Darrel Taylor
Thanks
Peak-hold now working well for both side.
But my problem is , i want to counting down side 0 to 1 ,2 , 3 ......... ( not 65535, 65534 , 65533 .......)

.
- 12th July 2007, 05:15
Darrel Taylor

You might want to just try the whole program I posted, instead of making the changes to yours. Because I think you've missed something.

With the SDEC modifier in the lcdout statements, it will read -1, -2, -3 etc. And will never show 65535.

There are several other subtle changes too.
<DT>
- 12th July 2007, 06:19
precision

Thanks it is work on lcd.
but on 7 seg. LED display , it is not work in +/- ,
this is my code

Code:

; CHIP 18F4550 DEFINE OSC 20 INCLUDE "MODEDEFS.BAS" CMCON = 7 ADCON1 = 15 CVRCON = %00000000 'CVref turned off TRISE = %000 TRISA = 11111 TRISB = %11111111 TRISC = %11111111 TRISD = %11111111 Symbol HC_latch = PORTE.2 symbol HC_Data = PORTE.1 SYMBOL HC_Clk = PORTE.0 B1 VAR BYTE B2 VAR BYTE B3 VAR BYTE B4 VAR BYTE B5 VAR BYTE B6 VAR WORD W0 VAR WORD w3 var word DUMMY VAR WORD DIGIT1 VAR BYTE DIGIT2 VAR BYTE DIGIT3 VAR BYTE DIGIT4 VAR BYTE DIGIT5 VAR BYTE DIGIT6 VAR BYTE W1 VAR WORD MASK VAR WORD LastW0 VAR WORD B1 = 0 B2 = 0 B3 = 0 B4 = 0 B5 = 0 W1 = 0 W0 = 0 w3 = 0 E1 VAR BYTE E2 VAR BYTE E3 VAR BYTE E4 VAR BYTE E5 VAR BYTE PAUSE 500 '------------------------------------------------------------------------- INCLUDE "DT_INTS-18.bas" ; Base Interrupt System INCLUDE "ReEnterPBP-18.bas" ; Include if using PBP interrupts ASM INT_LIST macro ; IntSource, Label, Type, ResetFlag? INT_Handler INT0_INT, _ToggleLED1, PBP, yes endm INT_CREATE ; Creates the interrupt processor ENDASM @ INT_ENABLE INT0_INT ; enable external (INT) interrupts@ INT_ENABLE INT1_INT ; enable external (INT) interrupts '------------------------------------------------------------------------- LOOP: IF W0 <> LastW0 then LastW0 = W0 if ABS(LastW0) > ABS(w3) then w3 = LastW0 B1 = LastW0 DIG 0 B2 = LastW0 DIG 1 B3 = LastW0 DIG 2 B4 = LastW0 DIG 3 B5 = LastW0 DIG 4 '------------------------------------------ DIGIT1 = B1 LOOKUP DIGIT1,[$C0,$F9,$A4,$B0,$99,$92,$82,$F8,$80,$90],MASK E1 = MASK '------------------------------------------ DIGIT2 = B2 LOOKUP DIGIT2,[$C0,$F9,$A4,$B0,$99,$92,$82,$F8,$80,$90],MASK E2 = MASK '------------------------------------------- DIGIT3 = B3 LOOKUP DIGIT3,[$C0,$F9,$A4,$B0,$99,$92,$82,$F8,$80,$90],MASK E3 = MASK '---------------------------------------- DIGIT4 = B4 LOOKUP DIGIT4,[$C0,$F9,$A4,$B0,$99,$92,$82,$F8,$80,$90],MASK E4 = MASK '--------------------------------------- DIGIT5 = B5 LOOKUP DIGIT5,[$C0,$F9,$A4,$B0,$99,$92,$82,$F8,$80,$90],MASK E5 = MASK '--------------------------------------- HC_Latch=0 shiftout HC_data, HC_Clk, MSBFIRST,[E1,E2,E3,E4,E5,$C0] pauseus 1 HC_Latch=1 '--------------------------------------- endif GOTO LOOP ToggleLED1: if PORTB.1 = 0 THEN W0 = W0 + 1 ELSE W0 = W0 - 1 ENDIF @ INT_RETURN
- 12th July 2007, 07:59
Darrel Taylor

Oi vey!
Where'd the 7-segment come from?

Oh well.

Code:

B1 = ABS(LastW0) DIG 0 B2 = ABS(LastW0) DIG 1 B3 = ABS(LastW0) DIG 2 B4 = ABS(LastW0) DIG 3 B5 = ABS(LastW0) DIG 4

- or -

Code:

W4 = ABS(LastW0) B1 = W4 DIG 0 B2 = W4 DIG 1 B3 = W4 DIG 2 B4 = W4 DIG 3 B5 = W4 DIG 4
- 12th July 2007, 08:48
precision

Oh..Thanks Sir Darrel Taylor.

working fine now. but how i show "-" sign for tension measurements.

One thing more , just for information.

my encoder is 1000 PPR
CHIP 18F4550
XTAL mount 20 mhz

Code:

__CONFIG _CONFIG1H, _FOSC_HSPLL_HS_1H DEFINE OSC 20

I lose the count in > 5 RPM with above code.

And if mount XTAL 20 mhz
and if i code

Code:

__CONFIG _CONFIG1H, _FOSC_HSPLL_HS_1H DEFINE OSC 3

this is work up to 20 RPM. No counts lose.
Is DEFINE OSC 3 will increase the speed of PIC ?

.
- 12th July 2007, 09:26
Darrel Taylor

18F4550
20Mhz crystal (22pF caps)

Use ...

Code:

@ __CONFIG _CONFIG1L, _PLLDIV_5_1L & _CPUDIV_OSC1_PLL2_1L & _USBDIV_2_1L @ __CONFIG _CONFIG1H, _FOSC_HSPLL_HS_1H DEFINE OSC 48
- 13th July 2007, 08:53
precision

how i show "-" sign for tension measurements. I mean when count below Zero.

.
- 13th July 2007, 09:01
Darrel Taylor

If LastW0.15 = 1 then the result is negative.

I'm not familiar with your display, so I don't know how to show the minus sign.
- 13th July 2007, 10:15
precision

Thanks a million Sir Darrel Taylor. My project is over.

i add this line,

Code:

If LastW0.15 = 1 then E6 = $BF ELSE E6 = $FF ENDIF HC_Latch=0 shiftout HC_data, HC_Clk, MSBFIRST,[E1,E2,E3,E4,E5,E6] pauseus 1 HC_Latch=1 '--------------------------------------- ' endif GOTO LOOP

Now my next step is "Calibration Factor" with Pitch of machine's screw.
I will start it Using Floating Point
Thanks again.
- 13th July 2007, 12:50
Darrel Taylor

I doubt that you need to use Floating Point.
It's a real pain.

Do you know the numbers yet?
pulses/mm or something like that?
- 13th July 2007, 13:52
precision

Sir my plan is,

When motor's pully moves 68 turns then Screw( worm gear ) turn 1 time.
Screw = 6 TPI ( then plateform moves 1 inch = 25.40 mm )
so 1 turn of screw = 25.40/6 = 4.233333 mm.
so 68 turns of pully = 4.233 mm
so 1 turn of pully = 4.233/68 = 0.062205882 mm

I will attach encoder of 6 PPR direct to motor pully.

code
pitch var word
pitch = 10368 ; (62208 / 6 = 10368)
dummy var word

loop: dummy = (pitch * ABS(lastw0))
w1 = div32 10000

so w1 = .01 mm least count
motor's 68 turns = encoder's 408 turns (10368 * 408 )/10000

so plateform moves 4.230 mm

This is my calculation

.
- 13th July 2007, 14:29
Darrel Taylor

Oh, OK.

I thought you meant the microchip Floating Point routines.

Sounds like you got it covered.