EAGLE suggestions

I just learned how to use eagle, so I decided to create a breakout board for the ATtiny family of 8pin microcontollers. I have attached my schematic, suggestions appreciated. It is my first one, after all. I also attached an image for those of you w/ out eagle.

Thanks!
baum

Screen shot 2011-04-11 at 6.38.27 PM.png

ATtiny.sch (117 KB)

Huh! The 7805 is probably bigger than the uC :slight_smile:
Why not ditch that and add connections for a 3xAA or AAA or 3.7V LiIon battery pack.

3.7V LiOn ? 5V for ATtiny 3xAA= 3x1.5= 4.5V ? 5V for Attiny.

And I can get a smaller [smd] reg, like the one on the arduinos.

Is that the ATTiny 13?

Speed Grade – ATtiny13V: 0 - 4 MHz @ 1.8 - 5.5V, 0 - 10 MHz @ 2.7 - 5.5V – ATtiny13: 0 - 10 MHz @ 2.7 - 5.5V, 0 - 20 MHz @ 4.5 - 5.5V

3.7V & 4.5V look okay to me.

No, its an ATtiny85. And I want to be able to power peripherals off of it. A wall wart + vreg can provide the voltage and current I need.

I also have a question about boards. 1. Can I make irregularly-shaped boards? (like the arduino) 2. How do I add silkscreen?

I think if you open a .brd file, then View, and Display Layers, playing around there seems to show that layers 25/26 are part of the silkscreen layers, others part of that also. Some of those also describe the board shape, play around. Using the arduino reference designs, you can figure out a lot of things like that.

OK. But how can I make the board look something like this: [attached]

Or how could I add a silkscreen element in that shape?

board.png

• Operating Voltage – 1.8 - 5.5V for ATtiny25V/45V/85V – 2.7 - 5.5V for ATtiny25/45/85 • Speed Grade – ATtiny25V/45V/85V: 0 – 4 MHz @ 1.8 - 5.5V, 0 - 10 MHz @ 2.7 - 5.5V – ATtiny25/45/85: 0 – 10 MHz @ 2.7 - 5.5V, 0 - 20 MHz @ 4.5 - 5.5V

I still think the 3.7V & 4.5V will work, if you have the room add a couple of holes for some other future use. Same for a xtal & caps.

I would add pullup resistor on reset, and switch to hard ground, vs relying on the weak pullup. Then have the reset go to the pin so that external signal can reset also by pulling low.

The board shape looks like layer 20.

I would add pullup resistor on reset, and switch to hard ground, vs relying on the weak pullup. Then have the reset go to the pin so that external signal can reset also by pulling low.

What do you mean? Isn't this how it is on the arduino?

Nope - pin 1 is pulled high, goes to external pin for reset, and thru a cap to the USB interface for a reset.

But isn't reset active low?

Yes - so pull it high fairly solidly with 10K pullup, then can have wires hanging off and will stay cleanly high until you want it low. Just like the arduino’s do.

The reset switch is in the wrong place; it won't allow an external device to reset the tiny via the connector pin, nor will is pass the reset signal to shield-like devices that need the signal (in fact, it'll keep them reset.) The arduino reset circuit has the AVR pin connected directly to the connector pin, with a 10k pullup to 5V, and the switch between the signal and GND.

  1. I fixed the reset pin (stupid mistake) :(

The board shape is generally OK, except for that long thin sliver in the upper left corner. That is going to be a problem on several counts. It will be difficult to manufacture which will make it expensive and hard to source. And it will be fragile and easy to break. Re-consider why you want to make such a thing and how you can use a more conventional design.

And perhaps it isn't important, but the inside corners will likely have some amount of radius from the router bit used to cut the board.

That was an arbitrary shape. I just wanted to know how I could change the board shape (but I figured it out: Split tool)

But how about arbitrary silkscreeens?

But how about arbitrary silkscreeens?

You can draw whatever you want in any of the existing silkscreen layers (tPlace, tNames, tValues) or define a whole new layer for your special pieces. When you generate the Gerbers, you pick which layers will be "merged" onto the silkscreen gerber, and can include whatever you want. Don't draw silkscreen items on the Dimension layer (although the Dimension layer is sometimes included in the silkscreen), because "Dimension" affects things like routing and polygon fill.

But how do I draw?

How can I draw shapes on the silkscreen? The only way I know so far of creating silkscreen is with a script that puts values, placement, etc. in the silkscreen layer.

What tool do I use to draw? I know what layer to draw on, just not how to actually draw things.

OK. I see that. But can I insert images (like a logo, etc.)?

Thanks for the help so far!

baum

p.s. the tutorial I took on youtube was excellent, except it didn't cover silkscreen all to much.