A first approach would use aÂ PDA. The bot is connected to, with a RS232 cable (iPaq PDAÂ have a serial connector). PDA then talks to the server using its builtin wifi or bluetooth and sends collected data. There’re even Linux distros which can be used on an iPaq, such as theÂ familiarÂ (works nice!). The problem is each time I need a bot to be wireless, I need an iPaq. And an iPaq isÂ expensiveÂ (~ 120â‚¬ @ ebay). And big. And the one I have can’t have wifi or bluetooth.
|WifiÂ ? Why can’t I use aÂ Wifi boardÂ ? It’s way tooÂ expensiveÂ (~ 200â‚¬)… UART to wifi boards cost a lot, because from UART to Wifi, there’s a lot. AnotherÂ problem is the battery life. If I want my bots to be wireless, they also need batteries. And wifi eats a lot of energy.|
|Recently, I’ve found some niceÂ bluetooth OEM boardsÂ @Â Lextronic. Cheap (~ 30â‚¬) and easy to use (on paper).Â Battery life is okÂ using bluetooth. Yeah, bluetooth seems to be the solution. When I’ve come to see those boards, I’ve realized how small they are. WayÂ too small… That would be an advantage. But not for me, as I can’t even solder it (no pins, connectors are under the board). There’s another version: the OEM board is soldered on another board, with ready-to-use connectors. Even those connectors are too small, and this time this is twice the price (~ 65â‚¬).|
|So, what now ? Should I give up wireless robots ? When I’ve seen those bluetooth boards, the seller said: “Why don’t you use those tinyÂ XBee boardsÂ ? Problem is you’ll have to have another boards connected to your PC, since none handles theÂ ZigBee protocol“. And I said :”No way, I want a standard stuff”. Back to home, desperately giving up bluetooth, I’ve looked to those Xbee boards. ZigBee protocol seems to be a standard, but not well-known (Master FenyoÂ said: “It’s very usual, it’s also called theÂ professional bluetooth”. Quite nice ! ZigBee is also known to beÂ more reliableÂ andÂ uses less energy. Users report on forum those are very easy to use. And price is ok (~ 25â‚¬).Â Wikipedia showsÂ an interesting comparison, showing whyÂ ZigBee is a good choice for embedded systems:
ZigBee is my better choice. For now… The only problem is I need one on my PC. Next step is to check how this could be (very) easily done).