SX>Xbee

T Chap

I am going to prototype a project using the SX28 and Xbee's. The Xbee runs on 3.4v max. I understand the Xkey needs 5 volts. I really dont want to put a 5v and 3.3v regulator in the Tx remote running off a battery, but, if I want to leave the system in tact for testing and real time code tweaking without loading chips in and out, I don't see any options. I am actually using the Blitz, but I assume it is the same deal.

Can the Xkey run on 5volt rail and the SX be at 3.3v while programming? Not likely. Seems like if I want to use the actual product to both test and program, then I'd have to put a dip switch to the Xbee to kill the power to it while the SX and Sxkey were in 5 volts mode, then go back to 3.3v and switch the power back on to the Xbee. Kinda of a hassle it seems.

Post Edited (originator99) : 9/13/2006 10:01:54 AM GMT

Bean

Yes the SX-Key CAN run from a +5V input while the SX device runs at 3.3V.
What I do in my designs is run the voltage input directly to the SX-key header and to the 3.3V regulator input.
When I want to program the SX the input voltage MUST be 5 volts. But after programming the input voltage can be whatever the regulator can handle.

Bean.

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·

T Chap

Bean

Thanks but I am not understanding the reply. You said:

the SX-Key CAN run from a +5V input while the SX device runs at 3.3V

but then you said:

the SX the input voltage MUST be 5 volts

So if it is true that the SX-Key CAN run from a +5V input while the SX device runs at 3.3V, why does the SX need 5v to program? How are you switching the volages on a PCB?

Bean

I didn't say "the SX the input voltage MUST be 5 volts".
I said "When I want to program the SX the input voltage MUST be 5 volts."

Okay I have a voltage coming into my board that gets regulated down to 3.3V.
And that voltage is connected directly to the SX-Key header.
So, when I attach the SX-Key that input voltage MUST be 5.0 volts to program the SX on my board.

All I'm saying is, the SX on my board CAN run at 3.3 volts while being programmed by the SX-Key that has 5.0 volts going to it.

Bean.



▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Cheap used 4-digit LED display with driver IC·www.hc4led.com

Low power SD Data Logger www.sddatalogger.com
SX-Video Display Modules www.sxvm.com

There are only two guaranteed ways to become weathy.
Spend less than you make.
Make more than you spend.
·

Desy2820

I think Parallax made the SX Key Ring to connect between the SX key and the SX board.· The idea was that you would leave the target system at 3.3 volts while the SX Key operated at 5 volts.· You would need an external 6-9V supply for the Key Ring.·

When you wanted to program, disable the·oscillator on the target system (if needed), connect the SX Key Ring, your external·power supply, then the SX Key.·

I hope this helped!

Link to SX Key Ring:· http://www.parallax.com/detail.asp?product_id=45211

T Chap

Excellent, thats what I need.

T Chap

Bean

If you were to want to send a unique ID via the Xbee, which would you do below. Here are the details:

1. Two buttons on a remote, for example, one button sends 00000001 and the other sends 00000011. The other end makes decisions based on if it rec'd one or the other bytes.

2. For flexibility, I am considering adding a 4 pos dip switch for the SX to read in 1 of 16 possibilities to establish a "Channel" for both sides, as long as each side has the same dip setting, they talk.

Ok, so would you incorporate both sets of data into one byte to be sent? Or send a string.... first byte being the unique Channel number, although 4 bits are wasted, or, send one byte, let the first 4 digits represent the dip settings, ie 11110001 and the last for represent the info needed to take action? Would this require a mask to first derive the channel, then the data?

Thanks