WiFly doesn't start with volts on Rx pin

Wireless & IoT
1

I’m running an RN-XV module with version 2.38 firmware. The boot message says:

WiFly Ver 2.38, 12-11-2012 on RN-171

I have got the module configured and it automatically connects to my wifi network. I have a CP2102 USB-Serial adapter connected to the RN-XV’s serial ports and 0V. I am feeding 3.2V in to the RN-XV Vdd pin from a bench power supply.

I have noticed that when I pull power off the RN-XV and re-apply it, the device fails to start. I don’t mean it won’t connect, it literally doesn’t start up. Even leaving power off for some minutes and re-applying it, won’t restart the module.

  • - It takes no power (or less than 10mA that my PSU has as a minimum indication)

  • - None of the on-module LEDs come on
  • - The device won't talk to the attached USB-Serial adapter
    • If I remove the connector from the CP2102 to the RN-XV RxD (pin 3) and THEN apply Vdd, the module starts up, lights flash and it connects successfully to my wifi network.

    Is this a problem with the module’s hardware implementation? Or is there a sleep mode kicking in that I haven’t found out about yet? Any information or pointers would be great.

    2

    With the CP2102 connected, and the power supply disconnected, the module is being partially powered through the diode to Vcc on the RxD pin. This could damage the WiFly, so it is best to power up the RN-XV before connecting to its serial port. Or, skip the separate power supply and use a USB-serial adapter that can supply the required 3.3 V for Vcc.