zarnochwf1.com The ramblings of a sleep deprived college student.

The Wi-Fi truck project started in the early first quarter of 2007 when my cousin gave me a dead no-name brand large scale R/C monster truck.

The control board on the truck was dead, the voltage regulator having shorted out due to moisture and deciding to take the entire board with it. As there was no salvaging the board (all functions were carried out by one custom ASIC that was unobtainable on the surplus market) I began brainstorming a new controller for the truck, since i figured it would be an easy thing to do.

Around the same time in February(not sure if this was before or after i got the truck, i really should have kept a journal earlier on in the project) i had sent away for 2 Fon La Fonera wireless routers. The Fon router, if you don't already know and if you do i'm sorry to re-hash this, is a card-deck sized router that runs linux, has a single ethernet port, and a single 802.11g/b interface. It also has 5 easily accsesable 3.3V GPI/O lines and thanks to Lefinnois can do bit-bang I2C using 4 of them.

Having used I2C somewhat in some of my earlier microcontroller projects and wanting to "jump up" to embedded Linux programing I decided to use one fon as the controller of the truck, taking commands over a wifi bridge to my home network.

For the hardware interface controller i chose a Cypress PsOC mixed signal array development kit that i had ordered around the same time as the fon routers. It's main purpouse was to be the interface to the trucks rear motor and steering gearbox.

While i was waiting for an I2C driver to get ported to the Fon router, I had the truck temporarily controlled by a tethered optical mouse, which was fun, but I had to run after the dang thing with a mousepad in my hand. I also had to be careful when steering, since unlike the original controller board which had integrated in a servo controller, i was just dumping power straight to the steering gearbox motor. The reason for not using a standard servo controller is because the steering gearbox doesn't actually have the electronic guts of a standard hobby servo, it only has the pot and the motor.

After the tether experiments, i started working on the H-bridge that would control the rear drive motor.
I ended up making a monster bridge capable of taking 75A continuous. I know it's overkill, but i was tired of the l298's going into current limit mode, and the smaller fets i was using nuking each other.

I got to the point where i had a reasonable open loop PWM system going, including a rudimentary remote control system using the fon, but i had yet to get the steering to work right,

About that time the project was shelved, since i was in my first semester of college.

I am going to start actively working on the project once more, having recently bought an openservo V3 board for the steering servo in the front of the truck.

So, now that you've read all that, your probably wondering where the pictures are? Sadly, there arent any right now, unless i can pull a few off of my imageshack account. Seems i'm not good at documenting my work.

I do have a full system interconnect diagram i sketched out that i will post once i find the scan.