Long Story

So, for a whie now i've wanted to take a small motherboard, like a microATX or ITX, and put it on a (rather large) RC car. Add wifi, small control board, maybe cameras, and voila! You have an RC car that you can drive either up to 100 feet peer-to-peer from your PDA or laptop, or if you're in a place that has wifi you can use that to get a whole lot more range.

But there were some problems with that. 1) A new motherboard would be a few hundred bucks, and 2) the only car large enough to hold it would be a 1/6th scale Hummer or the like. Walmart sells the 1/6th scale Hummer, or used to, in three different colors, for $70. They're now out of stock in stores and online. It can't even be backordered. So there goes that idea.

Separately, I stumbled upon OpenWrt, a minimalistic Linux distribution for the WRT54G and various other routers. OpenWrt comes with a very basic core, and dnsmasq, a combination DHCP server and DNS forwarder, and ipkg, a very lightweight package utility that lets you downlaod and install additional packages. What more could I want?

There were also some mods that people figured out how to do, like adding a Secure Digital card, adding an LCD, two serial ports, a GPS, etc. But I wanted something even better than that. I figured, the router has a much smaller footprint than most small-motherboard PC's (actually, it's about the same size as a microITX: the router's circuit board is about 14x16cm; a microITX mainboard is 17x17cm). So... go to RadioShack, get an RC car for sale, and put the router in it! You can drive the car via WiFi, and using the GPIO pins, located by the developer of the SD Card mod, to drive the car! All you need is a small H-bridge chip like the SN754410, and you can hook that up directly to the motors instead of the car's RC circuit board.

The Car

So i stop by RadioShack to see what they've got. I made a paper cutout of the router, so I could have a size reference of the router. They had this one car, some Chevy pickup i think, just sitting there on the ground. I start looking at it - it's big enough to hold the router and a battery, it's got four wheel drive (but no differential), no remote, no box, nothing. So I ask one of the workers how much it costs. He says that I can't really use it without a remote. I'm like, "Oh, that's okay, I have other ways of powering it." The worker asks, "Kinda like a science experiment?" Me: "Sort of."

He goes over to talk to the manager. She tells the worker that it's got no remote. He tells her that I need it for a science experiment, and that I didn't need the remote. The manager says that I can have the car for ten bucks. Sold! It ended up being $10.60, because they still have to charge tax, according to the employee. I was expecting to pay about $20-$30 low end for a car that size; for my purposes, this car was perfect, and at $10(.60) it was a bargain!

Now I have to figure out which wires are which in the car, how to solder to the WRT54G without destroying it, and I have to get an SLA battery to power the router (it claims to want 12V 1A, but I doubt that; I'm still probably going to put in a 4 amp-hour SLA (they're about 4 lbs) so I can power both the drive wheels and the router off the same battery (some say that's a bad idea, when powering PC's and large motors off the same battery, but I figure, the router doesn't really care about the stability of the input power, and how much can these dinky little motors take, anyway?)

I'm off to build the Lizard, the wonderful Lizard made of the Linksys router running Linux and put on an RC car.



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