distance travelled

mataston · 07-22-2009, 10:29 PM

i want to build a device that i can connect to the obd2 interface, to enable me to record the distance travelled, i know i can see this by reseting the trip counter but, but i want to seperate business from pleasure. i was looking at maybe using a picmicro, having two push button switches, one for business and one for pleasure, when i get in the car i press which ever button and it will record the mileage. not sure how i would retrieve this info????
all help appreciated

Vitaliy · 07-23-2009, 09:20 PM

If this is for tax or business purposes, you also need to be able to enter a short description of the trip. E.g., "meeting with a client", "checking rental property", etc. No?

p2psmurf · 07-24-2009, 04:16 AM

For tax purposes there are many existing solutions.
See: http://www.accredis.co.uk/

kev000 · 07-24-2009, 04:35 AM

afiak, you can't get this from standard obd-II. I have written code to keep track of that via GPS though. However, it's not as accurate as getting it straight from the car...

michbound · 07-24-2009, 07:55 PM

Quote: Originally Posted by kev000

afiak, you can't get this from standard obd-II. I have written code to keep track of that via GPS though. However, it's not as accurate as getting it straight from the car...

You could derive this by requesting the speed from OBD II every minute (pid 0d) and continually adding the distance travelled in that interval. distance travelled would be speed/60 in this case added every minute.

for greater accuracy request the speed every second and integrate...

Thanks
Paul

Sonicxtacy02 · 07-24-2009, 08:09 PM

my vehicle maintenance plugin for RR does this. You have 3 mileage calculators. Total, trip, and waypoint calculation. All thats needed is a gps connection to RR. If you wish to do something standalone yourself, i can share my code for distance calculation

mataston · 07-26-2009, 12:30 PM

this info is allready computed by the car, it must be doing this via the information from the vehicle speed. the accredis is what i am trying to do but without the information being sent to various servers. No it is not for tax purposes, it is purely for my own information. I think the idea of polling the can bus to request the speed once a second, for the duration of the journey maybe an idea.

malcom2073 · 07-26-2009, 05:36 PM

Speed is usually read into the ecu as pulses from a magnetic pickup in the transmission. If you count the pulses not only do you get speed but you get 100% accurate measurement of how often the wheels have turned. Deriving distance from speed is inaccurate but the more samples per second you get the more accurate it is.