Archive for February, 2008

Day 29: Thing 29: One more thing

Friday, February 29th, 2008

(Archive of:

Today I “made” my 12 year old son program his own robot on his own computer.

It’s not a thing necissarily but a culmination of things (1,10,24,and,26). I didn’t take photographs of him doing it but I had him download the arduino platform and then walked him through running the blink example program and then he modified it to blink for random times. After that we wrote a program together which tested the touch sensor (thing 24) by driving slowly until it touches something.

After which we were exausted and he went to sleep.

It was good way to end the month.

Day 28: Thing 28: Charley plexed display

Thursday, February 28th, 2008

(Archive of:

Today I made the software for some hardware that I built a while ago.

The origional question was if I got 15000 leds for next to nothing and it costs 4-15 per 8×8 array (with the 4$ solution also needing 4 to eleven additional parts) to drive them are we getting anywhere? I looked at 2 solutions before realizing that the leds were to dim to do much of anything that interested me. One solution was to drive the led rows with cmos shift registers and sink the columns using TPIC6 based shift registers.

The other solution is called charlyplexing.

The idea is to multiplex a series of leds in a way that maximizes the leds per io pin avaliable. The led connections are paired and driven one at a time depending on the direction of the output pins. The remaining pins are tri-stated out of the way. It is a pretty intense software complexity vs hardware problem.

As only one led in the array is on at a given time, multiplexing the leds into an array reduces the brightness significantly making my near free leds impractical for this application. (These are 5×6 array, the fonts i used were for 5×7 displays)

Day 27: Thing 27: The last of the 4 led arrays

Wednesday, February 27th, 2008

(Archive of:

And then there were 4. Since this is finally the end of this particular resin.

I also went to get the right casting resin.

Now to wire them up….

Day 26: Thing 26: PC Based Arduino Programmer.

Tuesday, February 26th, 2008

(Archive of:

Since Aidan’s main computer is my old Del Lattitude running XP I realized that I should build a programmer for his system as it has a serial port. Basically its a max232 in a translucent plastic box with a buffer to drive some blinking lights so you know things are transmitting and recieving. Like my usb based programmer it has a cap on the DTR line to reset the board. The biggest problem I had building this was fining a db9 cable where pin4 was actually wired. The one I found was a bit bulky. The leds are “amplified” using a couple of chunks of plastic tubing.

Day 25: Thing 25: AntiSocial(ism)

Monday, February 25th, 2008

(Archive of:

I went to radio shack about a month ago and bought an utrasonic distance sensor made by parallax called a ping))).

I have been feeling cranky and anti social lately so I thought I should make something that didnt want to be bothered.

I am considering adding an air horn for people who dont respect its limits but think that the neighbors might not appreciate it much.

Day 24: Thing 24 — Mouse Whiskers (touch sensor)

Sunday, February 24th, 2008

(Archive of:

Two weekends ago Aidan and I went to radio shack and he was looking at these $9 bug bots which have a sound sensor, two touch sensors (antennae) and 6 legs. He was very interseted in both the walking mechanism and the touch sensor. We decided that we should add one of those to his arduino based mouse (A168).

Day 23: Thing 23: DELETED!!! (Button and screen)

Saturday, February 23rd, 2008

(Archive of:

After the last two days of disaster I got a new board in the mail.

It has one of the new atmel USB avrs on it which I would like to work with instead of the the ftdi chipset for programming avrs and arduinos. Rather than attempt to do another complicated and ambitious project I decided that my first project with this board should be to run the example keyboard code that atmel provides and modify it to send a “<shift><command>B” sequence followed by a “<CR>”. The sequence I use to “bounce” the 5o or so pieces of e-mail that get past my already overambitious mail filters.

I needed a button!

So I used the rem from resin for the displays to cast this one.

I thought a “Display” might not be a bad idea either.

Day 22: Thing 22: The $15 Wiring Board

Friday, February 22nd, 2008

(Archive of:

Since I had so much trouble yesterday porting with getting the bootloader on a new processor I though I should try something easier (these are things that I have been meaning to do for some time so it seemed appropriate to try them on a timeline).

Recently someone published the code for an Stk500v2 based bootloader for the new wiring platform. I have wanted to run wiring on several of the systems I have using the mega128 and the olimex header board that sparkfun sells. Between sparkfun and Ebay my per board cost is about 11 bucks. With the ftdi ft232rl usb to serial chip at $4 that would make the wiring platform affordable :)

On top of the latest wiring platform not running at all on my g4 I could not get the bootloader on either the sparkfun board or the et-avr-stamp that I had on the bench.

It turns out that part of the solution to this was in the next rev of the wiring software which fixed the bootloader issue. Once I got the bootloader to work with wiring I realized that the wiring platform requires a 32khz clock crystal to be connected to tosc1 and tosc2. Once this was added to both boards things started working.

Day 21: Thing 21 — Fred 644 (an attempt to port Arduino to another processor)

Thursday, February 21st, 2008

(Archive of: )

I wound up on the bus for much of the day so I took my laptop and ported the arduino “Core” to atmel’s Mega644 which has 4 times the memory of the new arduino as well as almost twice the number of pins avaliable. When I got to the bootloader I failed. This was a bit ambitious so I suppose I shouldnt be suprised. I will do another thing and post it here if I don’t get the bootloader working by the end of the month.

Day 20: Thing 20: Arduino on a (simm) Stick

Wednesday, February 20th, 2008

(Archive of:

In response to a conversation I had with “lady ada” in which she asked me “what is an arduino?” I have been pushing the question “What isnt?”. I have a bunch of stuff that I have built around the simstick platform which I wanted to reclaim so I put a 168 on a dt107 (dontronics) board and adjusted the IDE to see it. (this is in preparation for bigger and better mods)