SparkFun Forums

[konnichiwa]

I wondered if anyone had any tutorial on using 802.11b devices with an ARM/PIC chip. I want to control my R/C car with a camera by my PSP. I already have the cam/wifi psp interface setup, but i have not yet started on the car bit yet. any help anyone has on using/connecting with 802.11 devices would be great!

edit:

I suppose a simple solution would be to use a USB Wifi Dongle and connect to that via my chip.. would that be possible? Would i need a specific chip that supports USB, or would any of the I/O pins work? Is there any sample code for connecting to USB devices?

[SOI_Sentinel]

There's currently three ways I know to get this done.

One, the Wiport that you found in a different thread. $125 a pop for that.

Two, the EDTP Airdrop series. It' still somewhat in the early stages of development, but the test hardware appears promising. They're still developing the system, however. About $100 for the demo card, add a compatible compactflash 802.11b card. This is not just the hardware, but it gives you access to the software source. I haven't looked at it in the last half a year, though, despite being on the mailing list (all software was on a password protected FTP at that time, including people's code they were passing about on the list).

Three, a "gaming adapter". This is probably the bulkiest method. You can get them for $60-$80. Change the cord to something regulated from a battery (they're probably 5-12V). It'll mostly automatically bridge to a wifi network for you, you just need to use a 10baseT ethernet connection, which there are several options available there (Microchip's 28 pin part with a PIC - free TCP/IP stack available, the Xport series from Lantronics that provides a simple serial connection and has a few programmable IO too). This opton moves the connection and programming away from running a Wifi interface to an ethernet interface, which has more examples and hardware available online. Major issue is that it's by far the bulkiest and heaviest.

In any case, you're looking at $100-$150 to get a wireless connection at all.

A USB dongle would require a full USB stack to be built and a USB master chip. That would generally require something running Linux or Windows on your RC car. Can it carry a laptop? An actual option may be a power system, a Mini-ITX motherboard, and a 12V power system. You could then boot off a compactflash card or small hard drive and with the right drivers load USB drivers for your dongle. You could also use a PIC or something else with a serial (or even slave USB) interface to provide a way to toggle IO. Mind you, this is the most costly option, and will probably be as heavy and large as the Wifi gaming bridge option. It'd also put a big brain onboard your car.

Seriously, you have a large, complex project ahead of you.

[konnichiwa]

i'm expecting to loose whatever goes on the car (it has tendancies of smashing into walls at 50 mph) so i wouldnt want something that expensive on the car.

I guess i'll have to wait until they release Bluetooth 2 modules, V1 is much too slow for video.

[SOI_Sentinel]

Yeah, even then I'd be worried about your camera. You have one more option. If the camera is 802.11b, you might be able to find out if its hackable and perhaps piggyback the control signals that way.

Otherwse, make a mount on your current RC controller for the PSP somehow

Final option: use a different data radio and have it pipe into a local radio. From there convert the signal over either directly to Wifi (Wiport) or to ethernet via a small module and then via bridge to wifi. Not much more Rube Goldberg but you could place this somewhere, like the middle of your track or up high to help with possible interference and you could still use your PSP to drive it. This removes most of the bulk and expense from the car. It would add more delay to the commands, though.

And that's something I forgot: wifi has somewhere in the neighborhoot of 100 to 200ms minimum delays in it. You're going to have a tough time driving the thing if you already crash it into walls with direct control.

[jandirks]

Not really what you are looking for, I think, but this might be of interest for you: http://www.rcgroups.com/forums/showthread.php?t=456990