Entering AT mode, XBee transmits 0XE0

XBee & XBee Gateway XBee - 802.15.4
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1

Hi,

I used XBee series 1, Firmware 10ec, Function set XBEE 802.15.4.

The setup is the following:

[ul]
One XBee on a system I currently develop for
Another XBee connected to X-CTU to debug
[/ul]
When the system starts, it checks whether it’s XBee is set to 9600 bauds or 57600 bauds. To do so, 1st the serial port is set at 9600 and +++ is sent. If Ok is not received, then the serial port is set to 57600. Another +++ is sent, I get Ok and then send ATCN.

What bugs me is that on the other end, the XBee connected to X_CTU receives E0 E0 E0 E0 E0 E0 E0 E0 E0 (9 x E0) for each of the +++ and the ATCN command. These E0 will have the other party when connected fouled.

Why does the XBee transmists E0s when entering and leaving AT mode ? Is there a setting I am missing ?

Thanks

Gilles Plante

2

Sounds more like you are holding the CONFIG line low or the DI line is being held low as the radio will not transmit a 0xE0 value unless you provide it that.

3

Hi mvut,

I kind of agree that one does not expect the XBee to transmit something by itself, but that’s the reality, for example when using API mode and you get a acknowledge !

But back to my issue.

Test no 1

XBee 1, which is a peripheral is set to transparent mode (AP=0), 64-bit addressing mode (DH not 0).

XBee 2, which plays the role of the remote command connected to XCTU is also in transparent mode.

Each time XBee 1 receives ‘+++’ or ‘ATCN’ on the serial port, XBee 2 receives 9 times E0.

Test no 2

XBee 1 is set as before.

XBee is set to API mode (AP=2).

Each time XBee 1 receives ‘+++’ or ‘ATCN’ on the serial port, XBee 2 receives an API frame of type RX packet 64-bit address… and guess what it gets as the data, E0 E0 E0 E0 E0 E0 E0 E0 E0 !

I don’t know what the CONFIG line is. If you are talking about the *RESET line, it’s not connected. Regarding the DI line, it’s connected to the micro-controller, it’s not specifically held low.

If I would hold the *RESET line low, it would not be able to get into AT mode, but I can.

Note that when using transparent mode, but with 16-bit address mode, I don’t get these E0s. The remote command will be in API mode, so it will get a single frame, easier to manage than a series of E0 in transparent mode, but I would like to know why XBee 1 sends this string of E0s, and how to prevent that. I can’t find this feature documented anywhere.

Does someone know ?

Thanks