Bad Day

Posted by Erin, the RobotGrrl on Thursday, August 7th, 2008

It was a pretty bad day at my research lab today (aka: my desk next to the kitchen table, the kitchen table itself, and the floor) xD .

I was playing around with the Pololu uSSC’s, they were working great after I set the servo numbers!

But, I was a little troubled by two things.
1) When the program is sent to the Arduino, the Pololu uSSC gets a fatal error because of all the goobley that goes on the TX line when transferring the program to the ATmega.

2) When I pressed on the servo, the voltage drain was visible when the boards flashed on and off

For the first problem, I tried so many things with switches and crazy circuits … but it didn’t work. So I just used a jumper from the Arduino TX to another row where the SIN’s would be on the Pololu uSSCs so that I would only have to unplug one wire instead of two each time I was trying a program. That was OK.

For the next problem, I supplied 3 more volts in the form of two rechargeable AA’s. But… after looking at a breadboard for so long your eyes start to go crazy… I inverted the poles.

It wasn’t even a second later when the board became so hot that I panicked, tearing it out of the board. But, a cloud of smoke lingered in the air. At that time I knew it was toasted… even one of the batteries was smoking.

So at the end of the day, I have one extremely dead Pololu uSSC, one that doesn’t work, and one dead RBBB. I *think* the RBBB isn’t working because the ATmega isn’t working

So… yeah… pretty bad day. The lack of sun week after week after week doesn’t help either. It’s like living in a groundhog hole You get some sun, but once you go out, it disappears.

Posted in: Projects, Robot.

RBBBs and Pololu SSCs

Posted by Erin, the RobotGrrl on Tuesday, August 5th, 2008

I received the two RBBB’s, 1 FTDI TTL USB cable, and two Pololu Serial Servo Controllers (SSC) I bought a few weeks ago. Since then… I’ve been tinkering with them quite a bunch. I learned an incredible amount too from just a tiny board!

Building up the RBBB wasn’t too hard. At first, I printed off the wrong ‘instructions’ – which mind boggled me a bit until I noticed that they were indeed wrong. Once I had the right instructions printed… it was more simple. I was worried about the polarity of the bigger capacitors. After I had it all finished… I went and looked up the FTDI-USB cable specs. This cable is pretty interesting if you think about it, 1 wire turns into 6 more colourful wires -Gnd, CTS (clear to send), +5V, TX, RX, RTS (request to send). I downloaded the Blink program without any problems… until I wanted to test it. The LED wasn’t blinking! After about 5 minutes of intense thought, I realized that there was no LED on pin 13. That was a stupid mistake!

Another stupid mistake, but this one is funnier, was when I was trying to test the other RBBB.
… I forgot to put the chip into the IC socket. =D That really made me ‘lol’ for 10 minutes.

Then, I was trying to fit it into the breadboard… lets just say it took a longer than normal time.

When the Pololu SSCs showed up, I was pretty excited! Then when I saw them… they are REALLY tiny! It was a big challenge to solder these without them flying out of my hand. I don’t have a 3rd hand tool to hold it steady, so I would sometimes have to hold the ‘pinchy-things’ with my elbow and hold the solder and soldering iron with my hands. The headers were extremely difficult too…

Getting the Pololu to work with the Arduino is pretty aggrivating. I think I’m almost there, I just have to switch the input to the logic level side as I was using the RS-232 one. I thought that the Arduino used RS-232 on its TX line, but it doesn’t. It uses a non-inverted logic level (er well, that’s at least what I read). Tomorrow I plan on looking up the difference between the two

Here are some pictures… I finally threw the desoldering pump out the window (joking) and bought solder wick. Also finally bought NON-LEAD SOLDER! =D

Other than playing with these, I’ve been flow-charting A LOT of AI programs, and learning more first-order predicate logic. I really like logic and the probabilities and Bayes and everything!!!!! Also having fun thinking about random and bell curves… More back-dated Stanford blog posts to come (so many photos hahah)!

Posted in: Programming, Projects, Robot.