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

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!!

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.

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!