ELM 329 - User Manual

ELM329
Elm Electronics – Circuits for the Hobbyist
www.elmelectronics.com
CAN Interpreter
Since 1996, most vehicles have been required
to monitor their own emissions performance and to
report on it through an On-Board Diagnostics (OBD)
port. Initially, several different protocols were used
for the transfer of OBD data, but since the 2008
model year (in North America), only one protocol has
been allowed - the ISO 15765-4 CAN standard.
The ELM329 is a device that can translate the
data from an ISO 15765-4 interface into a form that
may be readily used by computers, smart phones, or
other devices. In addition, the ELM329 provides
support for several other CAN protocols (including
the SAE J1939 truck and bus standard), and for
sending periodic messages, mixed ID messages,
and for monitoring the CAN bus, to name only a few.
The following pages discuss the ELM329’s
features in detail, how to use it and configure it, as
well as providing some background information on
the protocols that are supported. There are also
schematic diagrams, and circuit construction tips.
• Power Control with standby mode
• High speed RS232 interface
• Automatically searches for protocols
• Fully configurable with AT commands
• Pin compatible with the ELM327
• Low power CMOS design
• Diagnostic trouble code readers
• Automotive scan tools
• Teaching aids
Description
Applications
Features
1 of 83ELM329DSC
Connection Diagram
PDIP and SOIC
(top view)
OBD Tx LED
OBD Rx LED
RS232 Tx LED
RS232 Rx LED
CAN Rx
CAN Tx
M0
M1
VDD
RS232 Rx
RS232 Tx
PwrCtrl / Busy
MCLR
Memory
Baud Rate
LFmode
Active LED
XT1
XT2
VSS
In1
In2
Control
CAN Monitor
Vmeasure
VSS
Block Diagram
IgnMon / RTSPwrCtrl
Command
and
Protocol
Interpreter
RS232
Interface
CAN Module
ISO 15765-4, SAE J1939
ISO 11898
4
4.00 MHz
9
10
Power
Control
15
16
14
PwrCtrl / Busy
IgnMon / RTS
PwrCtrl
11
CAN Monitor
/ A LED
Baud Rate
6
LFmode
7
18
17
RS232Tx
RS232Rx
Control
Module
status LEDs
3
26
27
25
28
24
23
CAN Rx
CAN Tx
22
21
M0
M1
5
Memory
1
MCLR
12
13
In1
In2
Control
2
Vmeasure
CAN
Monitor

ELM 329 Specifications