The document discusses OBD-II (On-Board Diagnostics II) systems, which provide vehicle owners and technicians access to vehicle subsystem status. It covers the types of vehicles that use OBD-II, common adapter types like USB, Bluetooth, and WiFi, and applications for fleet management and personal vehicle maintenance. It also provides information on the ELM327 microcontroller that translates the OBD interface, common tasks like reading diagnostic trouble codes, and developing mobile apps to interface with OBDII systems.

1. OBD-II Protocol
OBD systems give the vehicle owner or
repair technician access to the status of
the various vehicle subsystems
Hands-on guide to
on-board diagnostic
app development

2. What vehicles OBD-II covers?
Car
Van
Truck

3. B2B and B2C applications
FLEET MANAGEMENT PERSONAL USE
Cloud
OBD-II Reader
Smart Adapter
OBD-II Reader
Cigarette Socket

4. B2B and B2C applications
INSURANCE CAR MAINTENANCE
Cloud
OBD-II Reader
Operator
Cloud
OBD-II Reader
Operator

5. Wiki
Tasks
EML 327
The ELM327 is a programmed microcontroller produced by ELM Electronics for translating
the on-board diagnostics (OBD) interface found in most modern cars. A bridge between the
onboard computer in a car and handheld device
● Scan OBD-II system for codes
● Read PIDs
● Clear codes
● Aid in diagnostics

6. Types of adapters
USB
Bluetooth
WiFi
● Most widely compatible option
● Relatively inexpensive due to no wireless radio
● No chance of a dropped connection
● The cable can get in the way
● Relatively inexpensive
● Bluetooth is available in a lot of devices
● Incompatible with some devices, like iPhones
● Compatible with more devices than Bluetooth
● Expensive

7. ● Provide troubleshooting information or tips
● Record and playback live data
● Graph data or graph specific PIDs
● Read manufacturer or pending codes
● Utilize functions that require bi-directional communication
Tools
Scan ToolsCode Reader
● Read and display codes
● Clear codes
● Reset the check engine light

8. Mobile platforms. Android & iOS
Primary devices that can work with ELM327
Smartphones
Tablets
Laptops
Exception is iPhone, iPod Touch and iPad
due to how Apple handles Bluetooth stack.
Apple MFi Program

9. Emulator & car
Emulator Car

10. Step 1
Connect the OBDII to your vehicle’s/emulator’s OBDII port and
start/run the car/emulator
Step 2
Go to Settings on your Android phone
Step 3
Choose one type of connections WiFi or Bluetooth
according to used adapter
WiFi/Bluetooth connection

11. WiFi/Bluetooth connection
Step 4
Check that the Bluetooth/WiFi is turned on and tap on the OBDII
device from list
Step 5
Enter 1234 when prompted
Step 6
Launch your favorite app

12. Type of widgets
Gauge style
Numeric style
Plot Style
4 Param Style

13. Check engine
● Occasional flashes show momentary malfunctions
● It stays on if the problem is of a more serious nature, affecting the
emissions output or safety of the vehicle.
● A constantly flashing MIL is a sign of a major problem which can
cause serious damage if the engine is not stopped immediately.

14. Wiki
What is freeze frame?
Freeze Frame is an element of the Diagnostic Executive that stores engine operating conditions
at the moment an emission-related fault is stored in memory (when the MIL is commanded on).
This data can be used to help identify the cause of an emissions-related fault
Data Recorded
● DTC Description
● Engine Speed
● Vehicle Speed
● Airflow
● Engine Load
● Fuel Pressure
● Fuel Trim Value
● Engine Coolant Temperature
● Intake Manifold Pressure
● Open or Closed Loop Status

15. Obd2 modes
● to identify what powertrain information is available to the scan tool
● displays Freeze Frame data
● lists the emission-related "confirmed" diagnostic trouble codes stored
● used to clear emission-related diagnostic information
● displays the oxygen sensor monitor screen and the test results gathered about the oxygen
sensor
● a request for on-board monitoring test results for continuously and non-continuously monitored
system
● a request for emission-related diagnostic trouble codes detected during current or last
completed driving cycle
● could enable the off-board test device to control the operation of an on-board system, test, or
component
● used to retrieve vehicle information (VIN, CALID, CVN etc)
● lists emission-related "permanent" diagnostic trouble codes stored

16. Read RPM or speed
Get vehicle RPM/SPEED Send PID
Mobile App
OBD-II Library
ELM 327
Wireless Adapter ECU
Send PID
Deliver response Return response
in hex format
Convert to
human-readable format

17. Protocol
OBD-II library
Adapter Model
Connector
Command Executor
Service
Describes the protocol to use
(Wi-Fi or Bluetooth)
● uses socket opened by Connector
● schedules commands in a serial manner
● notifies execution status
Object describing OBD-II adapter (MAC
address, name, Protocol)
● enable Bluetooth or Wi-Fi
● connects and disconnects from adapter
● opens socket
● tracks connection state and notifies the system
● uses Connector to track state
● delivers commands from user to
executor and back
● notifies about connection and
execution state
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18. ● Phone and adapter are paired only once
● And the next time phone will immediately connect with
adapter
How to identify that adapter is plugged into a different car?
Car 1
VIN 1
Car 2
VIN 2
Car 3
VIN 3
Adapter
Send Mode 09 PID 02
Receive
0140:4902013147311:4A4335343434522:37323
532333637
Extract VIN "1G1JC5444R7252367"

19. Thank you!
If you have a project idea in mind, but don`t know where
to start, we're here to help you with literally everything
from discovery, proof of concept development, project
scoping to design and estimate.
We would be happy to help you with our expertise.
info@lemberg.co.uk

20. Links
List of sources used for our demo:
● http://www.obdii.com/background.html
● https://en.wikipedia.org/wiki/On-board_diagnostics
● https://en.wikipedia.org/wiki/ELM327
● http://cartech.about.com/od/Glossary/a/The-Elm327-Programmed-Microcontroller.htm
● http://www.auto-facts.org/resetcheckenginelight.html
● http://www.autozone.com/repairguides/S-T-Series-Blazer-Bravada-Envoy-Jimmy-Rainier-Trailblazer-
Xtreme/OBD-System-Terminology/Freeze-Frame-Data/_/P-0996b43f80cb37ca