High Resolution Timer & Speed Calculator

[WOZZY-2010]

Features:
1) MAXIMUM TIME: 99 MIN, 99.9999999 SEC ...Really just a display limitation
2) MINIMUM TIME: 0.0000522 SEC also a display limit at 9999.999998 MPH
3) Time Resolution: 200 nS = 0.0000002 SEC
4) Input single PULSE to Pin RC2
5) Displays Measurement and resets awaiting next pulse.
6) Data is sent out to 57600 N-8-1 Serial terminal on Pin RC6
7) Status LED shows when pulse is being timed.

Comments:
This was an experiment in precision of the code.
No oscillator is really this accurate.
Probably pretty close for relative measurements.
But Not for absolute measurements

Currently the speed is based on fixed distance of the optical sensors.
they are fixed and hard coded at 6.000 inches.
The circuit I use to derive the pulse is here:
http://www.picbasic.co.uk/forum/showthread.php?t=12614

Future Plans:
1) Add additional speed units (M/S, KMH)
2) Add user menu to set gate distance and displayed units
3) Add an oscillator correction factor after comparing it to bench-top timer.
4) Write settings to Onboard EEPROM
5) Try a 40 MHz crystal oscillator or other High accuracy clock
6) Build a thermal oven for crystal oscillator ...

Enjoy,
--Bob

[WOZZY-2010]

Please note that there are three include files in the above code which are required for it to operate.

N-BIT_Math.pbp
At its core is the Multibyte Arithmetic Assembly Library that was written by Alexander Avtanski.
The Assembly Library was wrapped for PBP by Darrel Taylor [Version:1.3 Beta (JAN 07,2010)]
This library is used to assemble the 64-Bit high precision math,
You can find reference to it in this PB Forum Thread:
http://www.picbasic.co.uk/forum/showthread.php?t=12433

DT_INTS-18.bas & ReEnterPBP-18.bas
DT_INTS-18.bas is Darrel Taylor's Base Interrupt System for PIC18F [Version:3.3 (MAR 24, 2008)]
ReEnterPBP-18.bas is Darrel Taylor's PBP interrupts for PIC18F [Version:1.4 (MAR 24, 2008)]
Both can be referenced at this PB Forum Thread:
http://www.picbasic.co.uk/forum/showthread.php?t=3251
Or directly from Darrel Taylor's web page here:
http://darreltaylor.com/DT_INTS-18/home.html
Please note that there are different versions for (PIC12F, 14F, & 16F) and for PIC18F.

--Bob

[aratti]

WOZZY-2010, interesting project and well documented. Thank you for sharing it.

Al.