Home > Tech geeks > Revisiting Wireless – at 2.4GHz

Revisiting Wireless – at 2.4GHz

smxbeenov08-002I finally have returned to working with my XBee wireless modules, and the arrival of a Xbee Explorer unit from SparkFun back in August has been instrumental in that effort – namely that I can now update the firmware of the XBee units. I was shocked when I opened the box and found the XBee Explorer is barely bigger than the XBee itself – tiny! At some point I may have to look at making SMD boards, because these things are just incredible. A quick installation of Digi’s X-CTU software and some device drivers and I connected right into the modems via USB.

At any rate, the XBee modems I got from SparkFun were running the older ZNet 2.5 firmware platform, and I was able to update a router device (v1220) up to an XBee ZB Mesh unit running the Coordinator firmware (v2021). Now that I’ve got a coordinator to set up the wireless mesh network, the other XBee units will connect to it and form the 2.4GHz wireless link I’ve been looking for. My hope is that this XBee ZB mesh network will eventually allow the pump skid control box, main sculpture unit, and PC to all work cooperatively without having to hardwire them together.

smxbeenov08-001xbeetest1The test circuit is very simple, and uses a PICAXE 14M to send a test message out through both the PICAXE programming cable and to the XBee unit. The end-device / router to coordinator transmissions worked perfectly, even at very small distances. For some bizarro reason, when I try to send something from the coordinator TO the other units it never arrives and echoes back in the coordinator received buffer – I guess I need to do some more reading on this. Once that is figured out, I plan on modifying the test circuit to use an interrupt to detect PC-to-PICAXE communications through the XBees, as would potentially happen as part of a setpoint change.

xbeecircuitdraftPoint being is I appear to have been successful at creating a mini mesh network with these units, and see this as a big step forward. Based on the test circuit, I’ve drafted up a 5V interface circuit to easily interface the Xbee to a PICAXE, however I want to verify the interrupt approach works before etching any PCBs.

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Categories: Tech geeks
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  1. November 29, 2008 at 2:25 pm

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