RFD21733 Datasheet, PDF (36/76 Pages) List of Unclassifed Manufacturers – Compliance Approved 2.4 GHz RF Transceiver Modules with Built-In RFDP8 Application Protocol

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7/10/2011 1:40 AM
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RFD21733 • FCC • IC
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RFDP8
RF Module
RFD21733
RFD21735
RFD21737
RFD21738
RFD21739
RFDP8
RFDANT
RFD21742
RFD21743
RFD21772
RFD21773
KEYFOBs
You will need to use the RESET pin, this pin normally is not connected for nearly all applications except for
reading back the ESN or possibly using it to have the mode pins re-read and change modes without power
cycling. The reset signal does not have to be used, instead of using reset you can use power the module off and
then back on. The reset is a cleaner way of doing it. If you are using the RFD21737, RFD21738, RFD21739,
RFD21772, RFD21773 eval boards, the reset signal is available on pin 5 of the 12 pin connector. Internal to the
RFD21733 / RFD21735, RFD21742, RFD21743 there is a 3.3K pull up resistor on the reset signal, so when you
are not using it, you can just leave it open.
To activate ESN read-back:
1. Place the module in a reset state by holding the /RESET signal low.
2. Hold the LEARN signal high. (On the Eval board you can press and hold the LEARN button.)
3. Release the /RESET signal.
4. Wait 250ms. If the LEARN signal goes low at any time during this 250ms interval, the module
immediately exits ESN read-back mode.
5. Release the LEARN signal.
6. Send the string “READ ESN” (all capitals, one space between the two words) at 9600-8N1 into the
module on the TXD Input signal. If this string is not received within 1 second, the module exits ESN read-
back mode.
The module will respond with the ESN and a firmware identifier on the RXD Output signal at 9600-8N1, and then
exit ESN read-back mode. An example of the output is:
314CE686:RFDP8 v1.2 11/18/08 08:45:16$
The ESN is 8 characters, representing a 32-bit number in hexadecimal format. A colon separates the ESN from
the Firmware ID. The Firmware ID is 32 bytes long. The output is terminated with a carriage return/line feed pair.
When the module exits ESN read-back mode, or if the LEARN signal is not high when the module exists reset,
the module will enter regular operation in Mode 2 or 3, according to the mode select signals.
IMPORTANT NOTE – Mode 3 and ESN Read Back
If at all possible, do your ESN read-backs in Mode 2 and not Mode 3. The reason for this is that in Mode 3,
if you happen to do this manually (by hand using an Eval board), once the radio outputs the ESN string, it
will enter normal usage mode meaning it will directly enter into LEARN mode when you release the
LEARN pin and then spend 10 seconds waiting for a packet to be received so it can learn its ESN. You
can prevent this by using a controller to time this activity, or you can simply do it in Mode 2 and not have
the concern. If you have any questions, always feel free to email [e-mail].
Watch a video demonstrating how to do the ESN Read Back using HyperTerminal and an Eval Board:
http://www.rfdigital.com/?targetpage=item&filterpn=RFD76021
Free Applications Support • Email your application questions to [e-mail]
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