2 questions regarding external /RESET on XBee 3 Cellular LTE-M/NB-IoT

XBee & XBee Gateway XBee - Cellular
1

Hi… 2 questions regarding the /RESET input to the Xbee3 (Cell Modem)

  • Is there any timing information on this provided? Specifically I’m wondering: a) how long does /RESET need to be held low, and b) is there any “max” timing on when the modem (specifically the UART interface) is active / responsive after releasing /RESET. I feel like there must be some magic datasheet (not “User Guide” but real datasheet) that I’m missing?

  • Regarding the force command mode… the manual reads: “you can recover the device to UART operation by holding DIN low at reset time. DIN forces a default configuration on the UART at 9600 baud and it brings the device up in Command mode on the UART port”. “Holding DIN low at reset time” – could you please be more vague? A timing diagram would be unambiguous. Sorry if I sound snarky, but if we’re engineering a product we’re not shipping hope & prayers with each module… we will conform to specifications and then expect things to work. So my question is: when is DIN pulled low relative to /RESET? On driving /RESET low? For any amount of time? Or only on releasing /RESET? Or both? Or…

Sorry for a little bit of snark but just give me the specs, Digi, please! And 1000 pardons if I’ve missed timing diagrams or tables with these values (sincerely).

Thank you!!

2

The reset pin is level activated. Bring the line low and then letting it cycle back to a high state will trigger a reset on the module.

While either powering up the module or triggering a reset, holding the Data In line LOW will cause it to enter Command mode. I am not aware of any timing information that has ever been measured for this function. But I am be assure you t hat holding the Data In line low for about 1 second after triggering a reset will place it in command mode with an OK being sent out indicating you are in command mode.

3

Thank you very much for the reply! Currently my code is only holding DIN low for about 10ms after releasing reset (bringing reset high) – I will extend this to 1 second and see if that works better.

Thanks again!