I'm working on a project and in order to cut down costs i buy the pieces from china.
There are very cheap products, but the documentation is not in english. My question is: how can i know what type of modules can work with arduino? I mean.. everything that has pins is good?
For example, i need to make my Pro Mini board a web server. What wifi module from here could do the job?
Thanks a lot!
I mean.. everything that has pins is good?
In theory yes, in practice NO.
the devices may not draw too much current (20mA) and should work at 5Volt (TTL level)
So many devices need an power source of their own.
What wifi module from here could do the job?
You need to write requirements (in detail) and compare these to the datasheets of the products.
Some wifi modules have a very low throughput others perform better.
What do you need for you application?
cheap prices comes at a price
Yes it's very risky buying from most of those ebay/Chinese places, there is no support or documentation and often dodgy designs as well.
Don't expect anything to work and you won't be disappointed (unless it also blows up you Arduino :)).
Rob
sonnyyu:
An other alternate for Arduino WiFi shield;-dbm123:
I really like the price and form-factor of the CC3000 WiFi module http://www.ti.com/product/cc3000and I REALLY link the concept of SimpleLink for a headless embedded device Wireless connectivity | TI.com
...
http://www.ti.com/product/cc3000#samplebuy
Can't beat price, free sample.
I'd recommend not risking your arduino with products you aren't sure of. Trust me, it can be pretty easy to fry them.
Thanks for the replies!
I am working on a data logger project: multiple (endpoint API) XBee's with ArduinoProMini's sending sensor data to the coordinator XBee in API mode.
Until here it's all simple. After that, i have two options: either i use an Android stick and attach to it a Sparkfun USB to Serial (to communicate with the coordinator API XBee) and a USB GPRS to act as a web server (don't know how I'll actually do it, because i'll need an usb hub for the two devices... but in theory it should work) 
On the other hand I could send the data to an arduino (instead of Android Stick), and attach to it a GPRS or WiFi (their prices kill me) module and make it act as a web server.
Do you think it's possible (and realizable) to make a XBee API to talk via the usb hub + usb to serial with the Android stick?
What adventages would each option have?
Thanks again!
A raspberry pi is cheaper and much more powerful than a WiFi shield and so may be worth looking into. I see many projects using both an arduino and a raspberry for this kind of thing.
sonnyyu:
The speed of 802.11g/n is not much important here. since Arduino can not fill in 11 Mbit/s of 802.11 b. but since 802.11n support 5.0 Ghz and it is much less crowded than 2.4 Ghz. The WiFi Shield which support 802.11n 5.0 Ghz is the way to go.
sonnyyu:
The newer 802.11y which use 3.7 Ghz and FCC allow high power Tx will bring distance up to 5000 m. You have no neighbor here. Private high way!
No Arduino wifi shield supports above frequency.
sonnyyu:
sonnyyu:
For people are looking for alternate for Arduino WiFi shield;-We have few threads about it:
Replacement of Arduino WiFi shield - WIFI router(openwrt compatible), Pogoplug, Raspberry Pi .
Arduino as VPN client? - #3 by sonnyyu - Networking, Protocols, and Devices - Arduino Forum
WIFI router Tp-Link WR703N for Arduino
Arduino - Wifi - iPhone - #7 by sonnyyu - Networking, Protocols, and Devices - Arduino Forum
WIFI router Tp-Link TL-WDR3600 for Arduino
Pogoplug for Arduino wifi and even housing and power supply
The bottom line is to start testing wifi with Arduino , all you need is used/junk PC plus few dollar wifi usb stick.
WIFI router Tp-Link TL-WDR3600 is dual radio 802.11n 2.4/5.0 Ghz router, use it with Arduino, you make Arduino run on 5.0 Ghz.
for 3.7Ghz support waiting is need.
2.4Ghz is OK.
5.0Ghz is better.
3.7Ghz is best.