The ELM 327 is a programmed microcontroller that translates the onboard diagnostic (OBD) interface to Bluetooth to interface with both PCs and smartphones. It is compatible with all cars that follow the generic OBD standard and can read real-time data from the vehicle's self-diagnostic system, including engine RPM, coolant temperature, vehicle speed, fuel trim levels, and more. The ELM 327 uses the OBD-II standard interface and supports protocols like SAE J1850 PWM/VPW, ISO 9141-2, ISO 14230-4 KWP, and ISO 15765-4 CAN. Open-source Android apps like Torque Lite and OBD App allow users to connect to the ELM 327

1. ELM 327 OBD
Davide Mazza
Sapienza University of Rome – DIAG – Pervasive Systems
https://github.com/davidemazza
https://www.linkedin.com/in/davide-mazza-33a9b291

2.  Produced by ELM Eletronic (v. 1.0 – 2005)
 Programmed microcontroller
 Translate the on-board diagnostic (OBD) interface
 Bluetooth
 Interface both PC and Smartphone
 Compatible with all cars that respect the generic OBD standard
 Last Version 2.1

3.  On-board diagnostics (OBD)
 Vehicle's self-diagnostic and reporting capability
 Introduce in the 1980s – Only idiot light
 Modern OBD – Real-time data
 Different Standard Interfaces
 ELM 327 use OBD-II

4. PINOUT
ELECTRICAL SIGNALLING
PROTOCOLS AVAILABLE
SPECIFIES
TYPE OF DIAGNOSTIC
CONNECTOR
MESSAGING
FORMAT

6.  SAE J1850 PWM – pin 2 and 10
 SAE J1850 VPW - pin 2
 ISO 9141-2 - pin 7 and 15 (optional)
 ISO 14230-4 KWP - pin 7 and 15 (optional)
 ISO 15765-4 CAN – pin 6 and 14
 SAE J1939
1 8
9 16

7. ELM 320 ELM 322 ELM 323 ELM 325 ELM 327 ELM 328 ELM 329
SAE J1850-PWM X X
SAE J1850-VPW X X
ISO 9141-2 X X
ISO 14230-4
(slow)
X X
ISO 14230-4 (fast) X X
ISO 15765-4
(CAN)
X X
SAE J2411
(SWCAN)
X X
KW1281 (SAE J28
18)
SAE J1939
(250kbps)
X X
SAE J1939
(500kbps)
X X
SAE J1708
(J1587)
X
SAE J1708
(J1922)
X

8.  Engine RPM
 Calculated Load ValueCoolant Temperature
 Vehicle Speed
 Short and Long Term Fuel Trim
 Intake Manifold Pressure
 Timing Advance
 Intake Air Temperature
 Air Flow Rate
 Absolute Throttle Position
 Oxygen sensor voltages
 Fuel System status and Pressure
 Other . . .

9. Egine ECU diagnostics tool that uses
a cheap Bluetooth ELM / OBD
adapter to connect to your car OBD2
engine management system
 Android App (available on Google PlayStore)
 Record Data Trips
 Widget Sensor
 Different display types
 DTC trouble codes
 Connection also GPS
 Upload data logs
Torque Lite (OBD2 & Car)

10. My personal Trip with Torque Lite

11. My personal Trip with Torque Lite

12. OBD App
 OBD is a basic application for the
connection with your ELM 327.
 Detection data in real time.
 Update data NOT delete (
comparison)
 Android App (available here and with qrcode)
 Choose which data sensor see
 Real time update data sensor
 List of your trips
 Select obd protocol
 Compass
GitHub repository: https://github.com/davidemazza/OBDApp