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ELM329
ELM329DSC
Elm Electronics – Circuits for the Hobbyist
www.elmelectronics.com
AT Command Descriptions (continued)
wakeup message will use standard 11 bit, or extended
29 bit IDs. The default setting for WH is 7DF.
WH wwxxyyzz
[ set Wakeup Header to… ]
This AT WH command accepts a four byte (eight
digit) argument, takes only the right-most 29 bits from
it, and uses that for the 29 bit Wakeup Header. You
may define a wakeup message to use a 29 bit ID even
if the current protocol uses 11 bit IDs. The last
assigned wakeup header (11 or 29 bit) determines
whether the wakeup message will use standard 11 bit,
or extended 29 bit IDs. By default, the wakeup header
is initially 11 bit, and so nothing is defined for a 29 bit
ID until you assign a value.
WM [1 to 8 bytes]
[ set Wakeup Message to… ]
This command is exactly the same as the AT WD
command. It is provided in order to be compatible with
the ELM327 instruction set. The default setting for WM
is 01 3E 00 00 00 00 00 00.
WM0, WM1, WM2
[ set the Wakeup Mode… ]
This command is used to set the Wakeup Mode.
The modes are defined as:
0: wakeups are off (disabled)
1: wakeups are sent at a constant rate
2: wakeups are sent if no other message has been
sent in the AT SW time.
The default value for this option is 0 (off). If you
wish to change this, you will need to change PP 23.
WS
[ Warm Start ]
This command causes the ELM329 to perform a
complete reset which is very similar to the AT Z
command, but does not include the power on LED
test. Users may find this a convenient way to quickly
‘start over’ without having the extra delay of the AT Z
command (it is about 1000x faster than AT Z).
If using variable RS232 baud rates (ie AT BRD
commands), it is preferred that you reset the IC using
this command rather than AT Z, as AT WS will not
affect the chosen RS232 baud rate, and AT Z will.
Z
[ reset all ]
This command causes the chip to perform a
complete reset as if power were cycled off and then on
again. All settings are returned to their default values,
and the chip will be put into the idle state, waiting for
characters on the RS232 bus. Any baud rate that was
set with the AT BRD command will be lost, and the
ELM329 will return to the default baud rate setting.
@1
[ display the device description ]
This command displays the device description
string. The default text is ‘CAN Interpreter’.
@2
[ display the device identifier ]
A device identifier string that was recorded with
the @3 command is displayed with the @2 command.
All 12 characters and a terminating carriage return will
be sent in response, if they have been defined. If no
identifier has been set, the @2 command returns an
error response (‘?’). The identifier may be useful for
storing product codes, production dates, serial
numbers, or other such codes.
@3 cccccccccccc
[ store the device identifier ]
This command is used to set the device identifier
code. Exactly 12 characters must be sent, and once
written to memory, they can not be changed (ie you
may only use the @3 command one time). The
characters sent must be printable (ascii character
values 00x21 to 0x5F inclusive).