High Resolution Timer & Speed Calculator

**WOZZY-2010** · - 7th February 2010, 05:36

This PBP project is a high precision timer and Speed Calculator.
Its designed to be used with a 2 sensor optical gate, though it can accurately measure the time of any single pulse.

It is mostly an experiment to carry as much precision as possible.
But also a useful gadget in it's own right.
It uses Darrel' Taylor's Instant Interrupts and N-Bit Math (64-Bits) throughout.

The core program is based on an implementation of CCP1, TIMER-1 Interrupts that was originally developed by Bruce from Rentron.
http://www.picbasic.co.uk/forum/show...01&postcount=3

Here is the Start of the Code:

Code:

'******************************************************************
'*********************[ High-Resolution Timer ]********************
'******************************************************************
'**  Author  : Robert Wozniak,   Robert.Wozniak -at- gmail.com   **
'**  Notice  : This code may be freely used and distributed      **
'**            for use in non-commercial applications            **
'**  Version : 6.10 : Feb 06, 2010                               **
'**  Date    : JAN 14, 2010                                      **
'******************************************************************
'**  Versions:                                                   **
'**   6.0 : All 64 bit MATH, 99 min limit                        **
'**   5.0 : Working Timer and Speed Calculator with 64 bit math  **
'******************************************************************
'**   Hardware Tested: PIC18F4680 @20MHz                         **
'**   4x16 Parallel LCD Module                                   **
'**   PBP 2.60 / MPLAB IDE 8.40.000                              **
'**   Compiled with: [-n -ampasmwin] Build Options               **
'**   32 BIT LONG SIGNED INTEGER                                 **
'**                                                              **
'** Thanks to Darrel & Bruce at MEL PB Forums for Code examples  **
'**           Alexander for N-Bit Math...Excellent ASM code      **
'******************************************************************
'**  MAX OVRFLO=457763, COUNTS=44041 for 99min:59.9999998sec     **
'**  MIN OVRFLO=0, COUNTS=261 for 9999.999MPH                    **
'******************************************************************

PRECISION CON 8 SYSTEM        ; Set 8 bytes = 64-bit Precision for N-Bit_Math.pbp

INCLUDE "N-BIT_Math.pbp"    ; Include Alexander Avtanski's Multibyte Arithmetic
                ; Assembly Library Wrapped for PBP by Darrel Taylor [Version:1.3 Beta (JAN 07,2010)]
                ; Version:1.3 Beta (1/7/2010)
INCLUDE "DT_INTS-18.bas"    ; Include Darrel Taylor's Base Interrupt System for PIC18F [Version:3.3 (MAR 24, 2008)]
INCLUDE "ReEnterPBP-18.bas"   ; Include Darrel Taylor's PBP interrupts for PIC18F [Version:1.4 (MAR 24, 2008)]

DEFINE OSC 20

DEFINE DEBUG_REG PORTC
DEFINE DEBUG_BIT 6 
DEFINE DEBUG_BAUD 57600     ' 38400 BAUD N-8-1, PORT C6 
DEFINE DEBUG_MODE 1     ' 1 = inverted, 0 = true

DEFINE LCD_DREG PORTA       ' Set LCD Data port
DEFINE LCD_DBIT 0           ' Set starting Data bit (0 or 4) if 4-bit bus
DEFINE LCD_RSREG PORTA      ' Set LCD Register Select port
DEFINE LCD_RSBIT 4          ' Set LCD Register Select bit
DEFINE LCD_EREG PORTB       ' Set LCD Enable port
DEFINE LCD_EBIT 3           ' Set LCD Enable bit
DEFINE LCD_BITS 4           ' Set LCD bus size (4 or 8 bits)
DEFINE LCD_LINES 4          ' Set number of lines on LCD
DEFINE LCD_COMMANDUS 2000   ' Set command delay time in us (2000)
DEFINE LCD_DATAUS 50        ' Set data delay time in us (50)

TRISA=%00000000             ' SET to Output
TRISC.2=1               ' SET to Input
ADCON0=%11000000
ADCON1=%00000111
T1CON.7=1         ' Set Timer1 to 16 bit mode

LED         VAR PORTD.1       ' Alias PORTD.0 to LED
I       VAR BYTE 
J       VAR BYTE 
OVRFLO      VAR LONG        ' Timer1 Overflow total
COUNTS      VAR WORD        ' Timer1 Counts after falling edge capture
PRESET      VAR BYTE
OVFLS32     VAR LONG
COUNTS32      VAR LONG
TSEC32        VAR LONG
OVFLS64       VAR BYTE[PRECISION]
OVFLS64M      VAR BYTE[PRECISION]
COUNTS64      VAR BYTE[PRECISION]
TSEC64        VAR BYTE[PRECISION]
BITS16      VAR LONG
BITS1664      VAR BYTE[PRECISION]
TMIN64      VAR BYTE[PRECISION]
TSECINT64     VAR BYTE[PRECISION]
TSECDEC64     VAR BYTE[PRECISION]
CONVSEC     VAR LONG
CONVSEC64     VAR BYTE[PRECISION]
AA32      VAR LONG
AA64        VAR BYTE[PRECISION]
BB32      VAR LONG
BB64      VAR BYTE[PRECISION]
CC32      VAR LONG
CC64        VAR BYTE[PRECISION]
TMIN        VAR LONG
TSEC        VAR LONG
TSECINT       VAR LONG
TSECDEC       VAR LONG
DISTINCH      VAR LONG
DISTFT      VAR LONG
DISTFT64    VAR BYTE[PRECISION]
DISTFT64M   VAR BYTE[PRECISION]
FPS32     VAR LONG
FPS64         VAR BYTE[PRECISION]
FPSINT      VAR LONG
FPSINT64        VAR BYTE[PRECISION]
FPSDEC      VAR LONG
FPSDEC64      VAR BYTE[PRECISION]
MPH64     VAR BYTE[PRECISION]
MPHINT64    VAR BYTE[PRECISION]
MPHDEC64    VAR BYTE[PRECISION]
MPH32     VAR LONG
MPHINT      VAR LONG
MPHDEC      VAR LONG

' ****** Setup Variables with Initial Parameters and 64-BIT Constants
I = 0
J = 1
PRESET = 3              '  ********** PER OVERFLOW LOOP TICS CORRECTION **********
BITS16 = 65536 * 2          '  ********** COUNTS MAX * 200 NS PER TIC**********
@  MOVE?LP  _BITS16, _BITS1664
DISTINCH = 6000           ' ********** 6.000 inches  (MAX = 65.535 in) **********
DISTFT = ((DISTINCH*10000)/12)
@  MOVE?LP  _DISTFT, _DISTFT64      '  ********** CONVERT TO FEET **********
AA32 = 1000000            '  ********** BUMP UP RESOLUTION
@  MOVE?LP  _AA32, _AA64
@  MATH_MUL  _DISTFT64, _AA64, _DISTFT64M '  ********** BUMP UP DISTANCE DIGITS
CONVSEC = 600000000
@  MOVE?LP  _CONVSEC, _CONVSEC64            '  ********** BUMP UP TIME DIGITS


Pause 500
LCDOUT $FE,1
LCDOUT $FE,$80,"HIGH-RESOLUTION "
LCDOUT $FE,$C0,"     TIMER      "
LCDOUT $FE,$90,"  Version 6.10  "
LCDOUT $FE,$D0," Robert Wozniak "

DEBUG 10,13,10,13,10,13
DEBUG "HIGH-RESOLUTION ",10,13 
DEBUG "     TIMER      ",10,13
DEBUG "  Version 6.10  ",10,13
DEBUG " Robert Wozniak ",10,13,10,13,10,13

For I = 1 to 5
HIGH LED        ' Turn ON LED connected to PORTD.1
Pause 50
LOW LED
PAUSE 50    ' Turn OFF LED connected to PORTD.1
NEXT I
I = 0

;----[High Priority Interrupts (DT_INTS_18)]----------------------------------------
ASM
INT_LIST  macro    ; IntSource,   Label,   Type, ResetFlag?
  INT_Handler   CCP1_INT,  _Capture,  PBP,  yes
  INT_Handler   TMR1_INT,  _Timer1,   PBP,  yes
    endm
    INT_CREATE               ; Creates the High Priority interrupt processor
ENDASM

CCP1CON = %00000101     ' Capture mode, capture on rising edge
T1CON = 0               ' TMR1 prescale=1, clock=Fosc/4, TMR1=off (200nS per count @20MHz)
@    INT_ENABLE  CCP1_INT    ; enable Capture interrupts

to be concluded in next post due to length limitations.

The timer has a 200 nS resolution and can go for 99Minutes: 99.9999999Seconds.

Here is the Schematic of the setup

The Full Resolution PDF file is here:
http://www.picbasic.co.uk/forum/atta...1&d=1265519692

Here is an photo of the actual Circuit:

This timer was developed to use an input pulse from the 2-Beam Pulse Generator Circuit which I presented here:http://www.picbasic.co.uk/forum/showthread.php?t=12614

While this code looks like an abomination, it's actually pretty cool that all the math is done with 64 bit precision.

I'm pretty new at all this, so I'd really like to hear your comments or criticism.

This is a work in progress. I have several features I'm still planning to include.

I'll follow up with a post with some comments and limitations.

Many thanks to Darrel, Bruce and Alexander for their excellent Code examples.