ELM624
AT Commands (cont’d)
AT Command Summary
be sent continually, until interrupted by the user.
Figure 1 shows all of the ELM624 commands in one
convenient chart. In order to help with the
Initially, the Control L/LANC standard required that
commands be repeated at least four consecutive
times to be valid (even though some machines
respond with less). The AT Rn command allows this
parameter to be adjusted as you experiment. The
default value for this setting is five (R5).
understanding of these, we have grouped the
commands into three functional areas, but this has
no bearing on how the commands should be used, it
is only for clarity. You may find this chart to be useful
when experimenting with the IC.
SP
[ Send a Pulse ]
The power to some Control L/LANC devices can be
controlled by sending a short pulse on the LANC
data bus. When issued, the AT SP command sends
a 150msec wide pulse for this purpose. See the
Power Control section for more information.
ELM624 AT Commands
general
2D use v2 Defaults
D use Default settings
I show the ID string
Z reset all
TP n
[ Trigger Pulse output on word n ]
Selecting this mode causes a short, negative-going
pulse to be output on pin 6 at the beginning of the
LANC word/byte selected by ‘n’. These pulses will
continue to be sent until interrupted by the user, as
long as there are synchronizing pulses to lock to.
Allowable values of ‘n’ are from 0 to 7.
responses
C1/0 Show on Change
E1/0 Echo on/off
L1/0 Linefeeds on/off
FD use Formatted Data
Q1/0 Quiet mode on/off
RD use Raw Data
The output pulse width is nominally one bit wide at
9600 baud (104µsec), and is meant to be used for
triggering an oscilloscope or logic monitor, in order to
view word ‘n’ in more detail. Note that the RS232
transmit circuitry can remain connected while using
this option, as the short pulse will simply be seen as
a start bit for a byte of value 0xFF. Normal RS232
output is stopped while in this mode.
requests
CS Check for Sync
D1/0 Duplicate to w2/w3
MA Monitor All
Rn Repeat n times
SP Send (power) Pulse
TP n Trigger Pulse on n
? Monitor All
Z
?
[ reset all ]
Sending AT Z causes the ELM624 to perform a
complete reset, as if power were turned off, and then
on again. All settings we be returned to their default
values, and the IC will be waiting for user input.
Figure 1. ELM624 v3.0 AT Commands
[ status ? ]
Issuing this command causes the current status
bytes to be continually obtained from the LANC
device, without sending any command to it. This is
an alternate way to issue the Monitor All command,
and is functionally identical to it.
ELM624DSD
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