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xbee dtr/sleep pin behavior

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I want to communicate between two xbee S1s with microcontrollers (mbed LPC1768). I can communicate fine with the two xbees connected to a pc with USB explorer and XCTU app. However, so far, no-go with the microcontrollers in the loop.

My question relates to the RST pin (pin 5) and DTR/Sleep pin (pin 9). When I check these pins with xbee powered by the USB, both pins are high. When I log in to the XCTU they stay this way until I select the console and then the "Connect" icon. At that point, the DTR/Sleep goes low and the RST stays high. The parameter SM (Sleep Mode) is set to "NoSleep [0]" for the xbee per the XCTU settings.

I assume that the Reset occurs when the RST pin is momentarily grounded -- so it should show high when in normal operation. I also assume that with SM=0 and no flow control that the DTR/Sleep pin is ignored. Is this correct or should I set the DTR/Sleep pin to ground rather than let it float when operating with the microcontroller.
asked Oct 27, 2015 in RF Solutions and XBee by jekain314 New to the Community (5 points)

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1 Answer

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RTS does not cause a Reset. What you are seeing is the flow control set to Hardware or Software within XCTU.

Yes, when the SM command is set to a Non Pin sleep function, the DTR line is used as Flow control.
answered Oct 27, 2015 by mvut Veteran of the Digi Community (14,874 points)
I was referring to the RESET pin (pin 5) and not the RTS pin -- RESET is called the RST pin on the xbee USB explorer board silkscreen. Can you explain why the DTR/Sleep pin (pin 9) starts high and then goes low when you click the "Connect" icon on the XCTU display? I am assuming that the XCTU sets the xbee to Sleep and then wakes the xbee when it is connected?
Sure, when you click on connect, XCTU opens the COM port using the hardware settings selected under the port settings. In this case, CTS, RTS and DTR.