ELM329
CAN Interpreter
Description
Features
Since 1996, most vehicles have been required
• Power Control with standby mode
• High speed RS232 interface
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.
• Automatically searches for protocols
• Fully configurable with AT commands
• Pin compatible with the ELM327
• Low power CMOS design
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.
Connection Diagram
PDIP and SOIC
(top view)
MCLR
Vmeasure
Active LED
Control
Memory
Baud Rate
LFmode
VSS
OBD Tx LED
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.
OBD Rx LED
RS232 Tx LED
RS232 Rx LED
CAN Rx
CAN Tx
M0
M1
Applications
XT1
VDD
• Diagnostic trouble code readers
• Automotive scan tools
• Teaching aids
XT2
VSS
CAN Monitor
In1
RS232 Rx
RS232 Tx
PwrCtrl / Busy
IgnMon / RTS
In2
PwrCtrl
Block Diagram
4.00 MHz
MCLR
6
Baud Rate
9
10
1
7
LFmode
CAN Module
ISO 15765-4, SAE J1939
ISO 11898
24
CAN Rx
18
17
RS232Rx
RS232Tx
RS232
Interface
23
CAN Tx
Command
and
Protocol
Interpreter
22
M0
16
15
14
PwrCtrl / Busy
IgnMon / RTS
PwrCtrl
2
21
Power
Control
Vmeasure
M1
12
13
In1
Control
Module
In2
11
CAN Monitor
/ A LED
CAN
Monitor
4
Control
26
3
25
27 28
5
status LEDs
Memory
ELM329DSB
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