Xbee power wiring

[Wildatheart]

I am attempting to connect an XBee Pro sitting atop the USB adapter board·to a BS2 OEM board.· Although this is a unique combination, I think my question is generic to all Xbee/adapter boards/BS2 forms of connections if the 1 thru 20 pinout remains the same in all cases.

First, I installed the adapter board in a generic Radio Shack blank printed circuit board.· Mistake #1... that covers up the silk screen ID of the pinouts on the back of the adapter board.· Mistake #2... I confused the VCC/VDD connections in an attempt to rethink the upside down pinouts.·

It is my belief that pin 10 of the XBee adapter board is ground (and that seems to be common with Pin 1).··That ground·is likely·commom with·the USB ground, the Xbee ground, and the BS2 ground.· It is also my belief that pin 11 is VDD.· (Yes, I do understand that VDD cannot be powered by the local VDD from the BS2 board and the USB power at the same time.)· But... with the USB disconnected, and when Pin 11 is powered locally by the BS2 board, it draws down the BS2 board voltage to about 3 volts and an error message of "cannot connect" results when I attempt to run any BS2 program.

Any help to understand the pwer connections with the BS2 and the XBee would be appreciated.· I wish the Parallax power connections were written as clearly as the soldering instructions for the adapter boards.· Thank for your help.

BTW... each of my 2 XBee's have remained operable throughout this ordeal - at least they respond·intelligently when connected to XCTU through the USB port.

[Franklin]

www.parallax.com/Portals/0/Downloads/docs/prod/rf/32400-XBeeUSBAdapter-v1.0.pdf (http://www.parallax.com/Portals/0/Downloads/docs/prod/rf/32400-XBeeUSBAdapter-v1.0.pdf)

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- Stephen

[Wildatheart]

Thanks, Stephen... but your·reponse does not address my delima.· The problem is... if pin 11 is·VDD (5 volts) fed from the BS2 board (in the absence of the USB connector), and if pin 10 is a common ground throughout the system, then why is the 'board voltage' drawn down to about 3 volts in the absense of the USB connection?··Likewise, why is the USB connection·feeding·3 volts through to the BS2 board·when only connected to the USB?·

[Wildatheart]

Wiring diagram in question is·attached

[Franklin]

Your diagram is almost unreadable but the xbee is a 3.3v ONLY chip and will be damaged if powered with 5v. There is a regulator on the usb board to take care of this. If you could post a better diagram perhaps I could follow your question.

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- Stephen

[Chris Savage]

Hello,

The USB XBee Adapter powers just fine from 5V obtained at the BASIC Stamp VDD pin. On the XBee schematic you clearly show what pin you're connected to (as best as can be seen by that picture). However on the BS2-OEM side you're showing the connection to the 5V line at the regulator rather than showing which pin you're actually connected to on the 20-pin header. Bear in mind that, as the XBee module is 3.3V, the 5V signals coming from the BS2 must be buffered before being sent to the XBee inputs. XBee outputs going into the BS2-OEM are okay without such buffering. Parallax carries a 74LVC244A for such a purpose.

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Chris Savage

Parallax Engineering
·

[Wildatheart]

Thanks all for the suggestions. Parallax tech (David) suggested I use fresh 9 Volt batteries. Problem solved!

On another recent forum, Joshua Donelson posted, "Can you try another power source besides the 9V battery? The XBEE module is a power hog, and a 9V is not the best supply for those types of applications. " After just 2 days of very intermitent testing I've already used up one of the fresh 9 Volt batteries.

These Xbee's must reeeeeally be power hogs! Seems strange... that battery still measures 7 volts.

Other than a wall wart, any suggestions as to how to power these things such that they can remain portable?

Note from experience... if the Xbee USB adapter board ordinarily receives it's power from the BS2 board, (then with the 9V battery disconnected) the USB connection tries to supply power to the BS2. No good. The BS2 chip/module must be removed - the Xbee sucks up just about all the available ccuurent from the USB port.

Gordon

[Franklin]

Use 4 AA alkeline batteries or 5 AA NiMH (or you could go with C or D cells if you need more AH.

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- Stephen