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Embedded device spawning a wireless network - which module...?

Hello,

Apologies for not asking a strictly Keil related question, but I was hoping somebody would be able to share with me his experience with wireless modules that make it possible for a device like an iPad or laptop to connect to the embedded device (in other words, it needs to allow others to connect to its own network). Is this a standard option of WiFi modules...? (I checked a couple of user manuals but it is not a 100% clear yet...). I have (currently) little experience with WiFi devices...

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  • If you really want to use 802.11 this module may be of interest to you too, since you specifically stated a 'client device'. However, you are limited to data exchange with another device by the method(s) they support (simple ASCII command language) much like a SIM300 or Telit GSM module. Downside: there is really nothing to 'learn' about 802.11.

    www.atim.com/.../rn-174-sdk-board-for-rn-171-wifi-802-11bg

    In stock @ Mouser for a reasonable price:

    www.mouser.com/.../

  • I have used two wifi modules so will try give you a summary of my experiences

    Both use AT hayes type commands ( eg serial uart to module sending eg AT+STCP=xx.....)

    Connect one nano socket approx £45 - no support only documents
    ***********************************
    To connect to an external server socket - easy and quick

    eg power up power up module,
    set config, (device ip, power saving modes, timeouts, etc)
    find AP, Find host(are you connected to a wifi network), find ssids , join ssid
    find host device (eg ping) ip to find
    open socket (ip and port to use)
    send data ( socket handle, data length, data)
    check if data recieved ( 10 bytes in wifi buffer)
    read data from module (I/10:abcdef...)
    close socket
    power down if needed

    found out by removing the command echo back it was a little easier to use module only responds with something like I/OK if command accepted I(0000) socket handle or say I(0005) reponse time to ping command

    a little disconcerting is how long it can take to process commands eg joining networks with security e.g. 30s

    Found in a car plant ( eg lots of metal and big moving things ) I could connect about 90 m away and send data to a linksys router acting as an AP

    but in a office block with roughly 15 or so wifi networks the range was only about 10 m ( appartently wifi module throttle back on tx power)

    you need some form of external power control simply because when it powers up it does a search for networks ( or something similar) and draws max curent about 200mA and if you have a flat lipo battery it drops the voltage enough to set of resets and it start again ( self buggering poopatron) can you guess how I know this ?

    if it cant open a socket on a external eserver it comes back with something like
    ERRROR (207)

    *************************************
    Gainspan wifi module (forgot model) (£25) - support from the uk office and a site in india but you can also pay support for about £500 if you need something a little more complicated

    more or less similar but half the price - seems a little quicker to respond to commands
    and still developing with this so learning but i like what ive seen.

    a little differernt in how you send the data and recover it but still easy to use

    *****************************************
    How they can be used

    try connect to an external server - eg find a wifi network join it, then try open a socket on an external server

    act as AP and open a server for client sockets to connect to( eg set the network ssid ) so you turn on ipad wifi search for wifis then attempts to form a socket with your system

    web provisioning - (Gainspan )eg wifi module acts as an AP and when connected too provides a web page to the connecting device.

    if you can connect to a phone module these are very similar

  • Yes on the connect one module

    but this is the gainspan module www.gainspan.com/.../GS1500M_modules.php