9XTend™
OEM
RF
Module
–
Product
Manual
v1.2.4
©
2005
MaxStream,
Inc.
Confidential
&
Proprietary
16
Binary Command Mode
Sending and receiving parameter values using binary commands is the fastest way to change
operating parameters of the module. Binary commands are used most often to sample signal
strength (DB parameter) and/or error counts; or to change module addresses and channels for
polling systems when a quick response is necessary. Since the sending and receiving of
parameter values takes place through the same serial data path as 'live' data (received RF
payload), interference between the two types of data can be a concern.
Common questions about using binary commands:
•
What are the implications of asserting CMD while live data is being sent or received?
•
After sending serial data, is there a minimum time delay before CMD can be asserted?
•
Is a time delay required after CMD is de-asserted before payload data can be sent?
•
How does one discern between live data and data received in response to a command?
The CMD pin [pin 10] must be asserted in order to send binary commands to the module. The
CMD pin can be asserted to recognize binary commands anytime during the transmission or
reception of data. The status of the CMD signal is only checked at the end of the stop bit as the
byte is shifted into the serial port. The application does not allow control over when data is
received, except by waiting for dead time between bursts of communication.
If the command is sent in the middle of a stream of payload data to be transmitted, the
command will essentially be executed in the order it is received. If the module is continuously
receiving data, the radio will wait for a break in the received data before executing the command.
The
signal will frame the response coming from the binary command request [Figure 2.10]
A minimum time delay of 100 µs (after the stop bit of the command byte has been sent) must be
observed before the CMD pin can be de-asserted. The command executes after all parameters
associated with the command have been sent. If all parameters are not received within 0.5
seconds, the modem returns to Idle Mode.
Note: When parameters are sent, they are two bytes long with the least significant byte sent first.
Binary commands that return one parameter byte must be written with two parameter bytes.
Refer to p17 for a binary programming example (DT command example returns two bytes).
Commands can be queried for their current value by sending the command logically ORed (bit-
wise) with the value 0x80 (hexadecimal) with CMD asserted. When the binary value is sent (with
no parameters), the current value of the command parameter is sent back through the DO pin.
Figure
2.10.
Binary
Command
Write
then
Read
Signal
#4
is
CMD
(pin
10)
Signal
#1
is
the
DIN
(pin
5)
sig
Signal
#2
is
the
nal
DOUT
(pin
6)
signal
from
the
radio
Signal
#3
is
(pin
9)
In this graph, a value was written to a register
and then read out to verify it. While not in the
middle of other received data, note that the
signal outlines the data response out of
module.
the
IMPORTANT:
In order for the XTend Module to recognize a binary command, the RT (GPI1
Configuration) parameter must be set to one. If binary programming is not
enabled (RT
≠
1), the module will not recognize that the CMD pin (Pin 10) is
asserted and therefore will not recognize the data as binary commands.
