When the Rubber Hits the Road: Make Your Computer Talk to Your Car

When the Rubber Hits the Road:Making Your Computer Talk to Your Car

Gary “Chunky Ks” Briggs<[email protected]>

Slides Overview

Me

OBDGPSLogger

ELM327 and OBDII

OBDSim

Demo

MeGrew up & Studied in England

Offered job in LA doing random Linux stuff

Which ended up being print drivers for 6 years

Now I work at a research nonprofit in Santa Monica

Mostly simulation and modeling

Really, this slide is so I havesomewhere to put this pic --->

OBDGPSLogger Genesis

Late 2009, I bought a car with an OBDII port

That's mighty tempting

Idealist requirements:

Linux, OSX. Windows maybe

Log data

No GUI. RasberryPi, SheevaPlug...

Log GPS as well as OBDII

Make pretty pictures

OBDGPSLogger Now

http://icculus.org/obdgpslogger

“It does exactly what it says on the tin. It logs OBDII and GPS data on Linux, OSX and others”

Mostly C, bits of C++

Open Source

Logs to SQLite

Hokey GUI

OBDGPSLogger in Google Earth

OBDGPSLogger, Still...

Reads only Mode $01 PIDs

Magically just works

Except I haven't patched in support for current gpsd

Google Earth output

There's a live version, too

Simple analysis stuff

Works with my bike...

ELM327 and OBDII

Originally invented at Elm Electronics, http://elmelectronics.com/obdic.html#ELM327

Most of the high-quality manufacturers implement their own chip firmware

The ELM327 datasheet taught me most of what I know

ELM327 and OBDII, AT commands

Standard text-based serial protocol

I use PuTTY on Windows, screen(1) on Linux

ELM327 commands might look suspiciously familiar to older members of the audience

ATZ for reset

ATE0/1 to turn echo on or off

Scantool.net have an additional “ST” command set

ELM327 and OBDII, Getting Data

In short:

> 01 0D

41 0D 1F

>

“Show me mode $01, PID $0D” [vehicle speed]

41 => 0x40 | 0x01

0x40 = success, 0x01 = requested mode

0D => requested PID

OBDSim Genesis

Got bored of walking out to car with my laptop

Went looking for ELM327 & OBDII simulator

Idealist requirements:

Command-line

OBDGPSLogger log playback

Actually honors ELM327 commands

Multiple ECUs

Multi protocol support

OBDSim Now

http://icculus.org/obdgpslogger/obdsim.html

Pluggable data generators

Works with all OBDII tools I've tried

In the same source as OBDGPSLogger

Has way more users than OBDGPSLogger

Native Windows [MSYS] using com0com

OBDSim Supported AT commands

ATAT{0,1,2} – Adaptive timing

ATD{0,1} – Display data bytes

ATL{0,1} – Linefeed

ATH{0,1} – Headers

ATS{0,1} – Space separators

ATE{0,1} – Command echo

ATSP[A]{0-9,A-C} – Set protocol

ATST{n} – Set timeout

@1, @2, @3 – Device identifier stuff

Cvdddd – Calibrate battery voltage

RV – Request battery voltage

ATD – Reset defaults

ATDP – Describe protocol

ATDPN – Describe protocol by number

ATI – Request device version id

ATZ – Reset device

ATWS – Warm start reset

EXIT – Exit OBDSim

OBDSim Demo

Launch on Linux, use “-c” to attach screen(1):

obdsim -c

ATZ, total reset

ATE{0,1}, ATS{0,1}, ATL{0,1}

As a developer, you'll turn them all off

For keyboard experimenting, turn them all on

ATI, @1, @2 for identifying device

Couple simple data requests [010D vss, 010C rpm]

ATH1, ATSP7 [CAN 29-bit 500], ATSP1 [J1850]

That's all, Folks