Zigbee on SPI

[mihies]

Hi guys,

How would you connect Zigbee to SPI bus? Should I consider using SPI->UART module and connect Zigbee to UART? I am asking this because I didn't find any Zigbee SPI interface so far.

[dunk]

there are lots of radio modules that use already use SPI. why not just use one of them?
i'm using these: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=784-1013-ND

as for converting UART to SPI, i've never used a dedicated chip but they seem to be lots there.
http://www.google.com/search?q=uart+spi


dunk.

[mihies]

Hi dunk,

I've though of using ZigBee just becuase a bunch of tutorials is using XBee boards. That said I am open to alternatives such as yours.
Beeing a newbie, I have a few questions:
- do I need to wire other pins besides Vcc and SPI. If so, do you have an example? I guess I have to wire IRQ to a free GPIO port on my controller, correct?
- do I need two of these to create a communication (or are different parts required) between remote and controller?
- how far does it transmit? Up to 1000m?
- how about energy consumption (compared to ZigBee)?

Thanks,
Miha

[dunk]

hey Miha,
most of your questions about those modules can be answered from the datasheet.
i would not recommend them if you are new to this though as they are not the most straight forward to get working.

there are plenty of other RF modules that use SPI for communication though.
maybe you can find one that is easier to interface.

i am curious why you want to use SPI with an RF module?
what are you using as your SPI master?
using the UART on an XBee would be far more straight forward. as you said there are online tutorials on how to do this.


dunk.

[mihies]

Hi dunk,

I am considering to use EDK(Plus) board for toying with robotics (I am still looking around for a suitable microcontroller).
http://www.sjjmicro.com/EDK.html
It supports .net microframework which I'd be very comfortable with (being a .net developer), it is reasonably small and reasonably priced. It doesn't have an UART though - just a SPI/I2S bus - that's why I am looking into available options.
On the other side of the wireless line I'd like to use my old PocketPC which has a SD/SDIO port. AFAIK SDIO is pretty much a SPI port. I guess one could attach all sort of SPI devices to it as long a driver is there.

Thanks,
Miha

[mihies]

hey Miha,
most of your questions about those modules can be answered from the datasheet.
i would not recommend them if you are new to this though as they are not the most straight forward to get working.

Why do you think it is not easy. I mean, isn't connecting SPI lines to the controller, Vcc and IRQ enough? Is there anything else on the hardware front that I should know? The only feature I am not that sure of is PACTL(n). It is OK if I ignore it?
I can manage the software part easily I think.

[dunk]

the hardware connections are as you describe and should pose no problems.

the configuration of the CYRF6936 chip on the RF module takes some working out though.
there is little documentation available so reading the slightly cryptic datasheet is your only option.

compared to a XBee where all you do is write data to the UART and it appears at the other end any CYRF6936 based module is going to be hard work.
it is still doable as long as you read the datasheet in detail.

for my application where low latency is more important than high bandwidth a CYRF6936 based solution is definitely the better option.

sticking with .net is going to greatly limit your choice of onboard computer.
have you considered looking into mono running on an embedded Linux platform?


dunk.

[mihies]

the hardware connections are as you describe and should pose no problems.

Great 

the configuration of the CYRF6936 chip on the RF module takes some working out though.
there is little documentation available so reading the slightly cryptic datasheet is your only option.

That was my concern, too.  The documentation isn't very well written and it lacks samples (a sample tells more than everything).
Nevertheless it should work with trial and errors 

compared to a XBee where all you do is write data to the UART and it appears at the other end any CYRF6936 based module is going to be hard work.
it is still doable as long as you read the datasheet in detail.

for my application where low latency is more important than high bandwidth a CYRF6936 based solution is definitely the better option.

Thanks, this info is valuable. Experience is the best source of info.

sticking with .net is going to greatly limit your choice of onboard computer.

Yes, I am aware of it. I'd be limited with a bunch of boards/computers. I am not sure at this point whether to go with .net or not. Being a .net dev I feel comfortable with .net mf (IDE, framework, etc.). OTOH as you say, you are limited.

have you considered looking into mono running on an embedded Linux platform?

Actually not, since I am not really too keen to wander into Linux world. Not that Linux is bad or something, just don't want to loose (valuable) time re-learning something I already know. Nevertheless I'll take a look.
Man, so many choices...

Thanks,
Miha

[arachne]

Hi..
fyi, Digi XBee modules with ISP will be available next month (july-aug 2010).
http://embedded-system.net/digi-xbee-zigbee-modules-come-with-spi-serial-peripheral-interface.html