Help with connecting XBee to BS2

Lex

I've bought a XBee Explorer Regulated board (http://www.sparkfun.com/commerce/product_info.php?products_id=9132) & a XBee Explorer USB board (http://www.sparkfun.com/commerce/product_info.php?products_id=8687), intended to be connected for a BS2sx & a PC, respectively.

I'm not sure if I've the right board as most posts I've come across uses a AppBee board. Are these boards usable?

Also, regarding the connections, is it possible to connect the board to pin 0-4 or any of the I/Os of the BS2?

sylvie369

You can connect any of the Stamp I/O pins to the Din and Dout pins on the XBee Regulated board: those are your transmit and receive pins (respectively). I think you
can connect them directly, though it's possible that you'll need a 10K resistor.

The XBee Explorer board is for connecting an XBee through a USB port to your PC, not for connecting an XBee to a Stamp. I believe you knew that already, right? It should give you a perfectly good "base station", as it were.

You bought the right boards.

Lex

Thanx. But I confused about the TTL voltage issue, as in for powering up the board.

Can i use the regulated 5V from the BS2 to power the board?

regarding the base station. what interface can be used to send out the signals? I've read that it's possible to use the hyperterminal in XP, is there any similar interface for vista as well?

Mike Green

The 5V regulated output from the BS2 is very limited (50mA total) and some of that current is needed for the Stamp itself. Some of the xBee modules draw as little as 35mA, so that might work, but it would be close. I'd recommend using an external 5V regulator.

I don't see where the SparkFun board does anything for the logic signals regarding 5V signal levels. It may be that the xBee modules have 5V tolerant I/Os, but I'm not sure. silvie369 is correct that you can often just put a series resistor between the BS2 I/O pins and a 3.3V device's I/O pins. The AppMod adapters made by Selmaware used a buffer designed for this logic level conversion (www.selmaware.com).

sylvie369

Mike Green said...
The 5V regulated output from the BS2 is very limited (50mA total) and some of that current is needed for the Stamp itself. Some of the xBee modules draw as little as 35mA, so that might work, but it would be close. I'd recommend using an external 5V regulator.

I don't see where the SparkFun board does anything for the logic signals regarding 5V signal levels. It may be that the xBee modules have 5V tolerant I/Os, but I'm not sure. silvie369 is correct that you can often just put a series resistor between the BS2 I/O pins and a 3.3V device's I/O pins. The AppMod adapters made by Selmaware used a buffer designed for this logic level conversion (www.selmaware.com).

I have routinely run into issues trying to power XBees from the same source as Stamp modules, and so an external power supply for the XBee certainly seems like a good idea.

Re. the SparkFun board's ability to work with 5V signals, I have to admit I'm just assuming it's okay, based on the product description:

"Description: The XBee Explorer Regulated takes care of the 3.3V regulation, signal conditioning, and basic activity indicators (Power, RSSI and DIN/DOUT activity LEDs). It translates the 5V signals to 3.3V so that you can connect a 5V (down to 3.3V) system to any XBee module."

However, Mike is certainly more knowledgable about this than I am. In addition, on double-checking, I see that among the comments on the Sparkfun product page is this one:

"@Valen - I question this too, as there's no level shifter shown in the schematic. Digi says (but not in the manual from what I've seen :-() that the I/O pins are *NOT* 5V tolerant, so I don't understand how/why they can say that above, at all. "

I wonder (Mike?) if there's a way to know if using a 10K resistor in series between the Stamp I/O pin and the pin on the XBee Regulated board will protect the XBee properly.

As an alternative, there are boards at adafruit.com that have a buffer built in. I also understand that Martin Hebel intends to make more of the currently out-of-stock AppBee-SIP boards, which I've been using regularly with Stamps. IMHO, they're the best option.