Wednesday, June 13, 2012

AVC: Test Runs, Propeller Serial to I2C

Test runs went a little better last night. I went in a little earlier tonight and left earlier too. The drive in was a little spooky with the smoky haze from the fire near Boulder.

The good news? The robot made it around twice in a row! However, during the last several runs the robot was back to drifting into curbs. I'm still analyzing why and what I can do to improve the estimation.

Meanwhile, on the obstacle detection front...

Propeller in 0.6mm pitch QFP, 8-SOIC EEPROM
I've built a board that makes AVRcam serial data available to the mbed over the  I2C protocol. It's based on a Parallax Propeller. If I'm lucky it might actually work, too.

Plenty of room for cute logos...
Maybe it's just me but I greatly prefer  I2C protocol over serial since many devices can be daisy-chained to a single port. It's a sad state of affairs when you run out of UARTs.

The software to run the Propeller board uses a slightly tweaked i2cslave object (Tim Moore and AiChip Industries) from the Propeller forums. It also uses a slightly tweaked FullDuplexSerial.

One cog is dedicated to controlling the AVRcam, sending the colormap for tracking and then putting it into tracking mode and gathering bounding box data.  Another cog makes the collected data available to the  I2C master.

There's a diagnostic serial port on the board so I can see what the thing is up to. And of course an FTDI programming port for obvious reasons. The bi-color LED is used to indicate system status.

Eagle files: Schematic, Board
Source code (latest)


  1. Scattered T-Storms

    Potential for severe thunderstorms
    Chance of rain:

    Yesterday i waterproofed my speed controller with some liquid electrical tape.

  2. There was water in the crater last night from some light rain.

    Good idea re: liquid electrical tape! I may have to do that, too.

  3. I'm bringing saran wrap and tape! I drove through the full crater and the only water entry I got was a big drop on the magnetometer.

    Maybe they should start an autonomous boat or submarine category in the canal/pond?



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