ELM327P datasheet(2/76 Pages) ELM

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ELM327

Elm Electronics – Circuits for the Hobbyist

www.elmelectronics.com

2 of 76

ELM327DSH

Electrical Information

Pin Descriptions........................................................................... 3

Unused Pins.................................................................................5

Ordering Information.................................................................... 5

Absolute Maximum Ratings......................................................... 5

Electrical Characteristics..............................................................6

Using the ELM327

Overview...................................................................................... 7

Communicating with the ELM327................................................ 7

AT Commands............................................................................. 9

AT Command Summary...............................................................9

AT Command Descriptions........................................................ 11

Reading the Battery Voltage...................................................... 27

OBD Commands........................................................................ 28

Talking to the Vehicle.................................................................29

Interpreting Trouble Codes........................................................ 31

Resetting Trouble Codes........................................................... 32

Quick Guide for Reading Trouble Codes................................... 32

Bus Initiation...............................................................................33

Wakeup Messages.....................................................................33

Selecting Protocols.................................................................... 34

OBD Message Formats..............................................................35

Setting the Headers................................................................... 37

Monitoring the Bus..................................................................... 40

CAN Messages and Filtering..................................................... 41

Multiline Responses................................................................... 42

CAN Message Formats..............................................................44

Restoring Order..........................................................................45

Advanced Features

Altering Flow Control Messages................................................ 46

Using CAN Extended Addresses............................................... 47

SAE J1939 Messages................................................................48

Using J1939............................................................................... 50

The FMS Standard.....................................................................53

Programmable Parameters........................................................ 54

Programmable Parameter Summary......................................... 55

Using Higher RS232 Baud Rates...............................................59

Setting Timeouts - AT ST and AT AT Commands..................... 61

Power Control............................................................................ 62

Design Examples

Microprocessor Interfaces..........................................................64

Example Applications.................................................................65

Modifications for Low Power Standby Operation....................... 70

Misc.

Error Messages and Alerts.........................................................72

Outline Diagrams....................................................................... 74

Index.......................................................................................... 75

Contents

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