Odometer

[mataston]

HI I HOPE SOMEONE CAN HELP i am trying to build an odometer for my car, the circuit is simple enough a hall effect trigger and a magnet to generate a pulse, i need a pic controller to count so many pulses before displaying 1 mile. as the propshaft on the vehicle is going to rotate several times before covering a distance of 1 mile, there fore producing a given amount of puleses before covering a mile. how can i write this in picbasic pro. also another part of the design i am not sure of is how to retain the amount of miles covered. so next time power is switched on it continues counting. all help is appreciated.

thanks mat

[mister_e]

depending of your car model and year but most of the time, they already have a sensor called VSS (Vehicule Speed Sensor). It's actually pretty simple to read from them. Some of them will produce 6000 pulse/miles, some other 4000 and the list is long.

If your car have this Sensor, you can find the info at the link bellow
http://www.rostra.com/rostra-obstacle.htm --> Search application guide

[mataston]

unfortunetly it isnt that simple as my car is a kit car and i am looking getting rid of the old cortina dials i have in it, and building some digital ones instead.

cheers mat

[mister_e]

O.K in the past Audiovox Cruise control (now Rostra) sold some magnet stuff to stick on the drive shaft and a sensor... i remember that time.

Yup, hall effect sensor is the way to go. Now you can begin by using a 16 bit internal counter and read the results after 1 mile. You should be able to do something with it.

Read datasheet in the TIMER section. Once done, do some test.

In the Code Example section, you can find a Frequency Counter thread. It should gives you some start point.

Good luck!

[mister_e]

Also, Microchip appnote DS41214A (CCP tricks and tip) is also a good reference

[mister_e]

mmm another idea here, as you already have something workable, you can probably modify it. Is this a Cable system? If so, you can probably modify the dash end and attach a Optical Encoder to create your VSS signal. Optical encoder OR Using some optocoupler stuff.

[Acetronics2]

unfortunetly it isnt that simple as my car is a kit car and i am looking getting rid of the old cortina dials i have in it, and building some digital ones instead.

cheers mat

Hi, Mat

Old dials work with a magnet rotating with the cable coming from the gear box...

i have somewhere a very very old kit intended to be a speed limit alert : It works with a self made core coil fixed at the rear of the odometer.

If interested ask me ...

For rear gear ... thinking to it make me laugh !!! : How much "reverse" miles do you really drive in your car lifetime ... ???

Alain

[mister_e]

Possibility to hack the current one too.

If your current cable go to a cluster 'motor', thereafter this motor use a serie or Gear and goes to your KM/Miles counter. Is it possible to remove the adapter + motor and read from that with hall effect sensor.. i think so.

mmm seems i had the same idea of Alain after all