Mesmic 2125

Was looking around Radio Shack last Friday and found a Mesmic 2125 accelerometer in the sensor bin, I also found a PING module from parallax too. Got the accelerometer, but not the PING module. I like to stay within a budget and I think I can find the sonic module cheaper online with S&H included. Got it home, got it hooked up, wrote a sketch to look at the data stream.   So may have to do some data sampling. Writing some procedures to do some data logging. I will find out tomorrow evening if they are worth the time it took to write them.

Working on bumpers and redoing the design

Well got the rocker switches for the bumpers. Just need to put a few pull down resistors, screw them in and attach the bumpers. I did find a Mesmic 2125 accelerometer at Radio Shack for $32.99 plus tax, but found a 3 axis one at adafruit.com for $20 plus S&H. The latter is out of stock though and has been for a couple of weeks now.

I did order the magnets for the tachometer part of Leo today as well. Using 1/4" rare earth magnets on the front wheels coupled with analog hall effect sensors. Will probably order them this week or find them on ebay.

Just need to mount the switches and redo the bumpers on Leo. I was thinking about putting the IR ranging sensors in the drive part of the body, but starting to run out of room in there with batteries, switches, the drive board and still need to put another or change out the battery packs altogether. A few different options, especially if I make Leo an autonomous being and therefore able to charge himself when he needs to. That is sometime down the road.

The drive unit will be using up 7 out of 11(I don't count the tx and rx pins) digital I/O pins and 5 analog pins. I have 3 clones that I bought from Dale and need to build them up, but need to get a lot more familiar with the arduino I already have.

Well off to do something, even if it's wrong!

I found the brain!! and I didn't drop it!

I didn't say I found my brain, that's still not found, probably next to my common sense too. Ah well on to the bot!

So far have a body with a tracked drive and motors, an excellent start. It's MCU is on the way. I ordered an assembled AtMega 328 and a battery cable. This is the best choice I've come across, it's pre-assembled, can communicate via USB cable, has 14k available memory, built in PWM, and has quite a bit of I/O and it's open source. I spent $40 and got ahead by three weeks on build time, win-win situation on budget and time.

So far, I have a body for Leo and his brain is on the way. Need to get a cheap mouse for his encoders and pick up some light weight wood for bumper material and body mods, along with some bumper switches(reed or such). I have been toying with different thoughts on the bumper switches, do I use reed type, momentary push button or something else? A few thoughts on the body modification, need to protect the tracks without encumbering them when the bumpers are hit, need enough enclosure to fit the AtMega 328 Adriano, an H-Bridge, batteries and maybe a cooling system(ie small cpu fan or such, I think ice would be bad there), and whatever internal sensors(triple axis accelorometer, digital compass, battery monitors and some sort of communications module....ie I can dream can't I?). Yes, I've been browsing the bot pages and want lots of things to put in Leo, but need to take baby steps so that it's all done right and not buggy.

Decisions made and Money Spent

1. Body with tracked drive & extras $30 (already had it, so really free)
2. AtMega 328 Adriano based MCU $30 (August)
3. Nine volt clip $3 (August)

Decisions made and probable budget

1. Encoders for the drive wheels $5 (cheap mouse from frys)
2. 1/4" thick pine for the bod mods $10 (Home Depot)
3. Bumper switches $20 (frys, radio shack, etc)
4. H-Bridge for the motors $2 to $10 (various)
5. Sharp Sensors (5 probably) Need to find out
6. Rechargeable 9 volt batteries (2 at least) Need to find out
7. Rechargeable AA batteries (8) Already have

Wish List

1. Triple axis accelorometer
2. Digital Compass
3. GPS Module
4. Better bot programming skills
5. Bigger Budget!!!

Hopefully, this has been at the very least entertaining, if not a bit informative.