ATTiny44 / Arduino programming pin connections

The MIT High-Low Tech tutorial on using an Arduino board as an ATTiny programmer has a diagram for connecting an Arduino to program an ATTiny45, but not for programming an ATTiny44. So I cross-referenced the corresponding SCK, MISO, and MOSI pins with the package pins, and came up with this:

That is, connect Arduino pins 10, 11, 12, and 13 to the ATTiny44 package pins 4, 7, 8, and 9 as shown. Ground goes to ground, and the Vcc pin on the Tiny connects to the 5-volt pin on the Arduino power header. (And of course, when I say ‘Arduino pin’ I really mean ‘Arduino header hole,’ but you knew that!)

I tested this with an ATTiny44A-PU and got an LED to blink, so I think this is good. I haven’t tested an ATTiny84, but assume it’s the same thing. Let me know if there are problems.

Grisbot Light Above Two Demo

Here is a demo video of grisbot performing in ‘Light Above Two’ Mode. This could be the basis of a game, in which the object is to steer the robot as close to a marker as possible within a limited number of moves.

Light Above 2 User Interface

This is the Scratch-programmed user interface for the second mode for grisbot to obey commands from a flashlight shined from above.

When a flashlight is shined on the robot with an intensity greater than user-selected value (a), the robot turns:

When the light intensity drops below (a)-100, the robot travels in a straight line and stops at user-selected distance (b):

The user challenge is an exercise in geometry/trigonometry to move the robot toward a target position by a series of turns and moves:

I’ve programmed this procedure in both Scratch and Arduinoese (aka ‘Wiring’) so that it will work on the test bed, but the robot has chosen now to break down. I think that while moving the microcontroller onto the breadboard today, I jiggled the wires so that they are either loose or crossed. So trouble shooting the hardware is where I’m at today.

Grisbug circuit test

Grisbug is like a hexbug, only with programmed features. It is programmed to blink its eyes when a flashlight shines on it. When the flashlight comes closer, grisbug ‘wakes up’ and the eyes glow continuously and the motor runs. When the flashlight is removed, grisbug still glows and makes noise for several seconds before going back to ‘sleep.’

(NOTE: In the video, it appears that on of the LED ‘eyes’ isn’t working. It is, but it’s very dim.)

What’s next: fitting it into a smaller, lighter enclosure. Then I’ll think about adding user programmability.

Mice Eating Watermelon!

Sammy and Sam Sam eating watermelon. Engineer bloggers are allowed to be off topic if it’s Sunday and if it’s cute.

grisbug instamorph

On Friday morning the bathroom sink plugged up and while looking in the cabinet underneath for the snake, I spied a siphon clip that I had made with instamorph. How fortuitous! I had completely forgotten — Instamorph, of course! Just what I needed for making the grisbug enclosure. (Well, perhaps.)

In case you’re not familiar with this stuff, it’s a plastic-like material that melts at 140 degrees F, can be molded into a desired shape, then hardens as it cools. And I thought it would make an excellent enclosure for grisbug, since being formed by hand it tends to end up in organic-looking shapes anyway.

I carefully weighed out an ounce (about $1 in bulk price), heated up a sauce pan of water, poured in the instamorph pellets for warming, and molded a mock-up like so:

I’ve laid out all the components here to show that there’s more than enough room inside to accommodate them. Indeed, I might be able to squeeze in a mini breadboard. I also have a free pin on the ATTiny, so that I could add another LED for internal color.

Grisbug: first concept

I’m sure everyone is familiar with hexbugs, which are selling for about $6. Well, I’m working on a design for a ‘grisbug’ which will aim for roughly the same price point but have expanded capabilities.

I priced the ATTiny at $1 (in bulk), the 2 LEDs at $.30, the two photocells at $.64, and the motor at $2.50, for a total of (check my math) $4.44. After checking Ebay, I found that button vibration motors are going for $1, which would bring the price down below $3.

Of course we’re assuming a kit, and that the casing cost is negligible. But it looks like I can match the price point of a hexbot — and make something that lights up and is programmable.

As you might guess from the dual photocells, grisbug would be programmable by holding it up to a computer screen and flashing commands. As to what to program, I was thinking that the user could program things like the light level at which the eyes blink on, then also the light level at which the motor runs. And maybe the motor could be programmed to beat out a tune, too!

In another mode, it might be possible to program the bug so that if light levels change abruptly, it reacts by flashing its eyes in warning, then buzzing. This might form the basis of a game in which the user tries to snatch an object away from the bug without moving too fast or too slow while a randomized time limit ticks down.

Well, at this point, I’m not even sure that an ATTiny will accept screen-flash programs. But if so, then grisbug could be an entry level product for young roboteers, with grisbot as its older brother.