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Topic: Sharing HardwareSerial with XBee in Arduino (Read 1 time) previous topic - next topic

CrossRoads

Xbee is also 3.3V interface, yes? So you need 3.3V level conversion also.
Look at TXB0104 for the interface
http://www.ti.com/product/txb0104
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
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Graynomad

You can leave U1 and U2 in, just swap the IO pin level depending on whether you want to talk to the PC or the XBEE. That way you aren't spewing XBEE crap up to the PC. Anyway you really still have to isolate the FTDIs TX output.

CR is right about the level conversion, you could replace U3 and U4 with a TXB0104 (or TXB0102).

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

guest1102

One question (Sorry if I interrupt your conversation)
Quote
Anyway you really still have to isolate the FTDIs TX output.

Why does he have to isolate it? Wouldn't it just work if he connects or disconnects only the Xbee's TX output (as he did it before by unplugging the whole Xbee)?

Brad Burleson


So, what I'm looking for is the way to switch Arduino Uno UART to USB when I try to upload new arduino firmware and switch Arduino Uno UART to XBee when USB is not connected.


Well I didn't see this mentioned, but there is an interesting blog post I ran into (http://www.billporter.info/how-to-add-multiple-uart-connections/) that suggests using a pair of 1K resistors on the xmit/receive lines.

This is on my "to-do" list to experiment with but I haven't actually tried it so YMMV, but I thought it might help.

Brad (KF7FER)

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