Member Since: July 9, 2006

Country: United States

  • Here's a great set of protocol software for the RFM (HopeRF) and Semtec radio modules.

    It's been used on Atmel Mega32's w/Arduino and on STM32Fxxx ARMs and Teensy 3.x ARMs processors too.

  • Note that in the US and certain other North American countries, the unlicensed ISM band is 902-928 MHz. Outside these countries, this band requires a license, e.g., mobile phone companies "own" various portions of that frequency band. In much of the EU, the unlicensed band is 868MHz but is a smaller frequency range.

    The RFM69 is software-tuneable to both bands. The frequencies are close enough so that the antenna matching is good enough.

    Mind the regulations!

  • I hope SFE gets more. These work great if you use needle-nose pliers to crimp the springs so the pins go in/out easily.

  • This cable lacks the DTR signal which is needed if you intend to connect to a microprocessor whose bootloader is triggered by DTR, as are Arduino and others.

  • 900MHz does have less attenuation per "mile" than 2.4GHz, for sure. Laws of physics. And the "B" model radio does say it has up to 250mW transmitter power. Lots more than typical 2.4GHz products. In the US, FCC regulations restrict the transmitter on-time (duty cycle) in this band, in a complicated combination of data rate/bandwidth and duty cycle. Products that use frequency hopping are allowed higher duty cycle/bandwidth. These radios do use frequency hopping spread spectrum. Amazing for the cost.

    But 28 miles, even with the required high gain antennas for that line of sight range - is a marketing stretch. You might get that with a 9dBi yagi (big antenna) and with both ends elevated to clear the "Fresnel" zone for that long distance.

    But for sure, 100mW or (the cheaper one) at 900MHz with modest antennas and some non-LOS is a good thing for range well beyond what 2.4GHz can do.

    This 902-928MHz band is No. America only. I don't think the EU (ETSI) has anything comparable - their 868MHz unlicensed is not enough spectrum to do FHSS like the 902-928MHz band.

    The 902-928MHz band, in the US, has lots of "SCADA" users in it, but that's very low duty cycle.

  • Class description says " how to configure and connect coordinator and router ZigBee Series 1 radios together."

    Wrong terms. Big confusion. Digi's trademark is XBee. And XBee is used for both Series 1 and Series 2 XBees. But Series 1 and 2 are totally different animals...

    "ZigBee" is the ZigBee Alliance's trademarked name of a network layer meshing protocol usable on XBee Series 2 (Ember chipset). ZigBee is available on many vendors' RF modules. The Series 2 (S2) XBees can run ONLY ZigBee and not the simple, non-meshing point to point or hub/star network "topology".

    Xbee Series 1 (S1) are not ZigBee capable, and often that's a good thing. They can use either basic 802.15.4 with or without a PAN coordinator, and address data to any node based on the 64 bit MAC address. That's a good choice for simple projects and for beginners. Like the MAC address of an Ethernet interface; or S1's can use Digi's own mesh protocol called DigiMesh. Arguably better than ZigBee.

    IMO, beginners should use S1 without meshing. Most simply projects don't need the complexity of Meshing, nor the complications of "iDigi" which is Digi's enterprise scale management system.

  • In the photo, the XBee modules are marked "MaxStream". That company invented the XBee and broke new ground. Digi International acquired MaxStream many years ago and retired the name MaxStream.

    So those XBees are really old. Almost collector's items.

  • No RF-way to solder on an antenna where there already is an antenna. Disrupts the impedance. There are XBee's with u.FL connectors so you can plug in a coax going to a variety of antennas.

    PCB antenna to me means antenna formed by copper traces on the XBee. That's what's talked about in the WRL-11215. There is/was an XBee with a similar antenna, in the form of a (blue) silicon chip antenna that mounts on the PCB. That kind of chip antenna is widely used in WiFi and Bluetooth. The antenna has poor/negative gain and an irregular radiation pattern. The PCB trace antenna is likely very similar to the chip antenna, but less costly.

    The wire antenna, if you have the space, and if the XBee isn't inside a ferrous metal box, is the best choice. If in an aluminum box- you may be surprised as to how RF-transparent aluminum is, vs. steel.

  • Can SFE and others just NOT SELL mag stripe readers? Would that kill the company?

  • Sparkfun... Please respect those of us who say that items like the Fio v3 - ATmega32U4 sku: DEV-11017

    Are way overpriced.

    More attention to overhead, margins, and other costs is needed.

No public wish lists :(