isn't the 85$ a setback for the wifi interface?
i mean, a massive deployment would be quite... massive in price also
Ethernet?
(23 posts) (10 voices)-
Posted 6 months ago #
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@matt - Thanks for the WiFly GSX pointer, it's a very interesting unit. Can the code on it be adjusted for specific I/O tasks, or is more like the XBee, where you get a bunch of configuration commands to use those pins in a number of pre-defined ways?
Posted 6 months ago # -
@mihai, yes! The price is a downer..our estimate now is $125 per device. There are some cheaper WiFi modules out there but many do not do DHCP, which we need, and the WiFly uses less power than some others. We presented the library folks with options for 433MHz RF, ethernet jacks, or WiFi (strongly encouraging WiFi) and they chose the most expensive one probably because it's the easiest to deploy and gives the sensors the freedom to go anywhere. But yeah..it clearly depends on if the 'client' can handle the pricetag.
Posted 6 months ago # -
@Jean-Claude - Hm, you can specify sensor/UART interrupts but I do not think that it is much different than the XBee's operation. The WiFly lists GPIOs but documentation is somewhat poor.. Sorry, is that what you were asking?
Posted 6 months ago # -
Yes - thx. To be expected, since the WiFi stack is probably fairly complex, maybe even proprietary. User-programmability would be risky.
Posted 6 months ago # -
The ethernet shield of nuelectronics ( http://www.nuelectronics.com/estore/index.php?main_page=project_eth ) is based on the ENC28J60. The shield comes with a simplified TCP/IP stack. At looks like UDP en TCP are supported as long as all communications fit in one package. There's a sketch available for a simple web server too.
Posted 6 months ago # -
Hi
I would prefer a Wiznet Chip.
They are more powerful and easier to program.
The Enc is pretty low level.
It is like a Xbee compared to a RFM12.
If you need many it is worth the hassle, but for one unit I would choose the comfortable one.http://www.sparkfun.com/commerce/product_info.php?products_id=9473
http://www.sparkfun.com/commerce/product_info.php?products_id=9026There is even a shield from Lady Ada where you can plugin the module from the first link.
Cheers
RubiPosted 6 months ago # -
@Rubi: any idea where i could get one of those wired ones in Europe (i hate customs taxes and crazy shipping rates)
but he's got a point about WiFi, it's a lot more flexible than wired.
Posted 6 months ago # -
Hi
Sorry I buy them from Sparkfun.
Shipping is about 10$ or 6€.
Not too bad imho.Cheers
RubiPosted 6 months ago # -
I Just wanted to report back on my experience on the nuelectronics ENC28J60 based ethershield. I got myself one just out of curiosity (15 euro's, so not too expensive).
First thing to do is to get the latest Tuxgraphics driver because the one on the nuelectronics site is outdated (that version won't even allow to route your packets through a gateway). You can get it from http://blog.thiseldo.co.uk/?p=329.
The driver works somewhat similar to the rf12_easy* functions where you regularly call a polling function that will handle some state that the library user needs not to know about. This way you can repond to http server request and perform a http GET in parallel. You can register a callback function that will react to the http result code of your GET once the request is completed. Similarly, you can register other callbacks (even a callback so you can check out who pinged you). There are some helper functions to make life easier, like an urlencoder so simplify assembling strings. The library is mainly http oriented with a bit of udp en icmp extra's. No generic sockets like in the official Arduino ethernet library.
All in all a usefull and easy to use library which works ok. You have to be aware of some limitations; the library can send only one TCP segment in a socket session, but for many applications that doesn't have to be a problem. Also note that there isn't much documentation, but if you examine the examples it becomes clear how it works.
One other thing that is noteworthy is that the ENC28J60 draws about 200mA, so it is a bit power hungry (it becomes warm, but not hot, to the hand). Then again, the Wiznet module specifies a 150mA draw, so relatively speaken it is not that bad.
Posted 5 months ago #
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