HopeRF feedback

Wolfgang Spraul wolfgang at sharism.cc
Tue Jun 22 04:48:13 EDT 2010


Werner,
(my bad, I forgot that most HopeRF discussions and folks are hanging out
on the discussion list, not developer list, argh. :-) Need to merge those
two lists, for now I cross-post my reply maybe some people there still
catch it...)

thanks a lot for all those links!
There will be more HopeRF related evaluation and tinkering in the coming
months, I don't have any substantial feedback now other than noting your
points... (and knowing they are archived)

Thanks again,
Wolfgang

On Mon, Jun 21, 2010 at 10:58:21AM -0300, Werner Almesberger wrote:
> Hi all,
> 
> Wolfgang told me that you're looking into using an ISM RF module
> from HopeRF. I sent him a number of comments and he asked me to
> post it to the list. Here we go:
> 
> One of my first questions was how you'd use this to connect to the
> rest of the world. I didn't find the idea of requiring another
> Nanonote plus USB cable plus USB-Ethernet or such particularly
> appealing. However, if this kind of protocol has any popularity,
> one would expect that someone is at least making a USB dongle for
> it.
> 
> I poked around a bit and indeed found an RF-to-USB dongle at
> Silabs:
> http://www.silabs.com/products/mcu/Pages/RFtoUSBRD.aspx
> 
> Unfortunately, it comes only in a develoment kit priced at USD 49:
> http://www.supplier-direct.com/silabs/Cart.aspx?supplierUVID=63410000&quantity=1&issample=0&partnumber=RF-to-USB-RD&pd=RF to USB Reference Design
> 
> But it gets better - here are the schematics (page 12):
> http://www.silabs.com/Support Documents/TechnicalDocs/RF_to_USB-RD.pdf
> 
> That's just how I had imagined one should to this :-) Perhaps one
> could even use a cheaper microcontroller, e.g., the quite similar
> C8051F326/7 at less than half the price. There, SPI would have to
> be implemented by bit-banging.
> 
> There's more. Silabs also have a complete MAC:
> http://www.silabs.com/Support Documents/TechnicalDocs/EZMac-EZHop_UG.pdf
> 
> Depending on TX power, with or without FCC-mandated frequency
> hopping. This MAC is a bit more featureful than rfm12lib. They
> even put in link-layer forwarding for meshes :-) Naturally, it's
> not compatible to rfm12lib. The sources, unfortunately with a
> restrictive license, are here:
> 
> http://www.silabs.com/pages/DownloadDoc.aspx?FILEURL=Support Documents/Software/EZMacPRO_setup.exe&src=DesignToolsWebPart
> 
> The frequency hopping may be worth stealing. The addressing
> scheme doesn't scale. (A BT-like approach with short local
> "addresses" may be a lot more useful.) I also have some doubts
> about the efficiency of their forwarding mechanism. At least
> the documentation doesn't make it sound particularly nice.
> 
> By the way, if there's a sufficiently stable 30 MHz clock in the
> system, you can even save that pesky crystal.
> 
> - Werner
> 
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