So Let it be Written, So Let it be Done!

April 9, 2007

Almost Five Days Left

Filed under: kamakula,robot,trinity firefighting — kamakula @ 12:44 am

This are not looking good.

  • Broke a gear tooth with a superglue – gearbox accident. Luckily, Publix sells nail polish remover (acetone) which fixed the motor. But now I must next day air a couple spare gearboxes on Monday.
  • Spent hours tweaking the makefile until I got the PLL correct. . .
  • Wrote up lots of code. . . but a lot depends on displaying stuff over serial. However, it turns out implementation of stdio is incomplete in WinARM. There are work arounds. . . but I get the feeling they will take a long time to work through.

Hopefully, when things pull together, work will progress quickly. Just need to figure out a way to pull it.

Things left to do:

  1. Cut out lexan for structural components.
  2. Test out encoder circuitry.
  3. Write quadrature encoder code.
  4. Write accelerometer code.
  5. Write ultrasonic sensor code.
  6. Test A2D (infrared sensors).
  7. Design tone detector circuit.
  8. Get serial code to work.
  9. Test PWM
  10. Figure out competition strategy/algorithm (chances are this will be be partially coded on my flight to Hartford).

I suppose I could work around the serial stuff by cutting and pasting from the sample code. . . I was hoping to have ISR driven print capability that was light-weight. . . but I guess I can sacrifice that for development time. After all, with the PLL, it’s running at 60Mhz and I’ve got plenty of code space. . .

April 7, 2007

One Week Left

Filed under: kamakula,robot,trinity firefighting — kamakula @ 11:52 pm
Tags: , ,

Herein we join the adventure already in progress, where kamakula (that’s me!) has one week left to complete his robot (appropriately and presciently named LastMinute) in time for the Trinity Firefighting Competition. I’m a little pumped since I just completed a 5k run (32:04) – my first such in pretty much ever and my first week running in almost half a year.

LastMinute is supposed to be a two wheeled balancing robot that utilizes the ubiquitous Tamiya motor gearbox for locomotion. It will sport homebrew optical encoders (to determine it’s pose and speed), an accelerometer (feel that tug – it’s gravity!), ultrasonic sensors (echolocation like a bat), infrared (I can’t remember which animal sees in infrared. . . but I know you’re out there!) for distance measuring and to detect (hopefully) the bright spot of the candle (fire!). We’ve also got the cheap SN754410 quadruple H-Bridge to drive those motors. What ties all this together is a Philips LPC2131, an ARM7 controller in the package of a TiniARM from New Micros.

At this point, everything is pretty much in pieces. The ARM7, H-bridge, an accelerometer are on a breadboard. . . but not hooked up together. I’m still getting up to speed using WinARM to compile programs for the controller, so that still needs to be worked out. I’m not sure if I can get the optical encoders to work and I’ve never used the accelerometer before.

However – the goals for this evening:

  1. Setup timer interrupts correctly on ARM7 by creating a clock application that counts up H:MM:SS accurately (displayed over a serial link).
  2. Layout and solder optical encoder circuit then test it detects black/white transitions using an LED (and inverter as a buffer).
  3. Test quadrature encoder code by outputting over the serial link counts per second and direction.
  4. Layout H-Bridge circuitry on breadboard and test capability of driving gearbox motors with PWM output from ARM7.
  5. Test closed loop speed control of a wheel.

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