Let's Make Robots!

Attiny-Duino or whatever?

Hi geeks ;-)

I am thinking about to shrink some of my projects. That's the deal. I am planning to build a Attiny-Duino.

What would you think about it's usage? For myself I would use it in the Insect bot to reduce the weight, costs and power comsumption.

UPDATE June 8 2012:

My first PCB since 1988 and I will call it AT-LUMI-TINY ;-) This board is still far from perfect (see the jumper wires) but it's my first 1-layer board created on the computer. 

It's 27mm x 27mm and contains 1x ISP port, 1x 6x3 header (two rows for the power supply one for the signal) for attaching servos, 1x LED on pin 0 and one port for the power. This will be improved later since the soccer board was etched tonight ;-) Happy drilling tomorrow...

UPDATE:

As I already wrote, the PCB is far from perfect. There is a version 2 with separated I/O pin headers 2x(3x3) for better routing on the board. This reduced the size of the board to 25mmx25mm. Pictures will come later.

UPDATE JUNE 19:

Birdmun did not let me rest ;-) I got the board even smaller (ok, I cheated with adding one jumper wire)

See picture.

and here in 3D

I am just trying how small is possible. This is not a competition but I have to say that birdmun gave me a hard time after releasing his  24.4 x 21.6 wonder :-) 

The board with that Attiny will be bigger in the final design since we need it also a bit handy and may add some more useful components. we are trageting a board with app. 30mm x 50mm.

If you get that one even smaller, then show it here ;-) but I doubt that it can be much smaller since the compoments set the minimum size. With all those standard 3x1 pin arrays I see no way to shrink it more.

Edit: As you can see in the comments birdmun found a error. That happens when you do things in a hurry ;-) I changed the resistor and doing this i was able to even shrink the board more. Now it's 20.3mm x 21.6mm.

On OddBot's request here is the schematic.

Click to enlarge the picture:

Schematics corrected!

 

UPDATE July 16:

Last night I etched the PCB for the first test. After drilling and soldering all the components I had a short circuit on the board which prevented the programming via ISP port but not the execution of the program when uploading it to the Attiny on the breadboard.

We tried the servos and got 3 of them working. However, the servo on Pin 3 was not moving at all. The connection from the Attiny is correct, power is there but no movement. I am not sure why but I guess it's something in the library and/or the programming. 

Also the timer is srewed up. A delay(1000) for example flashes the LED like delay(50) under normal conditions. But this can be adjusted in the programming. Tomorrow is the troubleshooting and debugging, if the PCB is ok then we are going to send the files to the factory. Pictures and short movie coming soon...

 

This is the PCB we etched and tested.As you see the size is bigger than before. The reason is not to build the smalles board (this we proofed in our little competition) but to build a board which is handy and can be used in different projects.

Circuit diagram (click the pic for big):

The LED on pin 0 is missing in the circuit plan since it was added directly in the BRD file.

I an still sure that we can improve a lot but that's it now. If we don't find something to improve or to change we will send the to the factory. Video is uploaded and ready to go. In the Video are just two servos connected since the USB does not power that much load. With the external power supply we attached 4 servos...but only 3 are moving for above mentioned yet unknown reasons.

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Oh, there's enough room to squize in a TO92 v-reg (about 250mA) on Lumi's board. As for yours, you can make it smaller if you use a 2 layer board. It all depends on your needs. Of course, if you use SMD, you can make it smaller than a quarter. But anyway, both boards look nice, congrats both of you!

I was shooting for single layer for my first foray into toner transfer. I didn't want to make my life too hard to start with. :)

sorry, double post...

@Max: Yes, i did programm my Tiny's with help of this page.

@OddBot: Yes i know, but I want to build my own one ;-) Also want to use it as a educational board for our workshops.

@mogul: Yes i know that too. We had already trouble to fit the program into that tiny memory. But on the other hand, it's only for projects which does not require more than the Tiny can offer. I don't want to build a 4-leg walker with that. For programming purpose, we are going to include a standard 6-pin ISP header.

Here is the 6-pin header already included, buit the µC is an Attiny2313, not the 85 

Soon I will modify my insect bot with this new board to lower the costs for the workshop and make the build even more easy.

The insect bot is running with 2 servos and one ultrasound sensor and just a coulpe of lines code, good to use the Tiny.

I have been down the ATtiny road, and I would say it's not worth it. At least not for my purpose. True the chips are cheaper and smaller, but it's only a few dollar saved on each chip and the compactness completely disappeared then I soldered the smd converter board on a piece of perf-board.

If you are going to mass produce gadjets on manufactured boards, SMD tinys probably will be an excellent choice.

On the software side, coding for a tiny chip is simply harder than for a mega chip, so many constraints, and forget about using more than a single arduino library in your code.The serial software upload through the bootloader is a nice feature too.

I have no hard facts to back me up on the last issue, the power consumption, but I think you will be able to run a ATmega328P-PU ($4 @ ebay) at similar low power as the tiny's


Perhaps you should consider SparkFun's new breakout board for the ATmega32u4. This is the chip being used in the new Leonardo boards and has a USB socket built in.

One of Lumi's goals were cost. The SparkFun board is $20, compared to $4 for a ATmega328P-PU.

The size is definitely bigger too.

You can even use them just like Arduinos with fewer pins, of course.

http://hlt.media.mit.edu/?p=1229

I used a 45 to build my first walker.  It had epileptic fits.  That wasn't because of the tiny though-it did the same thing with the Arduino for brains.  The problem was the mechanical engineering.

I never shared it here.

The real advantage is the size of course, but you lose a lot of that if you put the USB serial on it.  Using the HLT method above you can program on the breadboard and solder an 8DIP socket into place and switch it out as you see fit.

 

Can't you just isolate the required pins with resistors, diodes, or jumpers? Or, are you saying the USB serial will cause issues due to memory usage? The board I have drawn up and etched is using an 8 pin PIC and I have isolated the required ICSP(In Circuit Serial Programming) pins with resistors and diodes. I am hoping my choice will work.

I was talking about the physical size and weight that adding a chip and the actual USB outlet added to the board.  What you're doing should work. I have one running currently as a "second brain" to an Arduino-based robot that uses its TX/RX pins for I/O.  I just make sure the unit is off when I connect it.