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[on:]

Here's a little toy I just built...

It's like a small Arduino based on the ATtiny84. It has a connector for a little OLED screen (the Tiny84 has no serial output so a screen is very useful!) and a ZIF socket for easy chip changes (handy if you need to program a bunch of chips for finished gadgets).

Photos below. If anybody wants more info, drop me a line.

Edit: The display is one of these:   http://www.ebay.com/itm/170842973484

[Reply #1 on:]

Hm any chance of a pic of back of board or schematic?
I'd like to do something similar for tiny85

It's literally just a case of connecting the pins from the ISP header to the tinyXX. It really is that simple...

I've done it with a Tiny85 for another device I built for driving some LEDs, see this thread: http://arduino.cc/forum/index.php/topic,125212.0.html

On the Tiny85 you connect to PB0/PB1/PB2 for MOSI/MISO/SCK.

PS: I'm going to do a Tiny85(duino) next. I don't think they make 8-pin ZIF sockets though...

[Reply #2 on:]

I was thinking of using one of those sockets and just wiring up 8 pins say at the top end
That way I could add to it later if need be I have one 6 pin plug with wires sprouting everywhere plugged into a small breadboard at present but I'm always putting the chip in the wrong holes!

I just leave it all attached to the usbtiny programmer so I was looking to tidy that up

[Reply #3 on:]

I was thinking of using one of those sockets and just wiring up 8 pins say at the top end
That way I could add to it later if need be I have one 6 pin plug with wires sprouting everywhere plugged into a small breadboard at present but I'm always putting the chip in the wrong holes!

I just leave it all attached to the usbtiny programmer so I was looking to tidy that up

Sounds like what happened to me...I was forever building and rebuilding this circuit on breadboards (switching between Tiny84 and Tiny85) so I decided to make something I could use over and over.

In theory you could make one with one chip socket and two ISP connectors - one ISP for Tiny84 and the other for Tiny85. That sounds risky to me though, better to have two boards and avoid breathing the magic smoke.

For the Tiny85 version I think I'll use one of those 14-pin sockets and cover up the bottom three rows of holes with something so I can't put the chip in the wrong place. I could even take step-by-step photos during the construction.

PS: One other thing I did while I was making this was put a power switch across the "power" jumper on my ISP programmer. That's turned out to be really handy. I can cut the power whenever I'm connecting/disconnecting the board it or changing the AVR chip. All ISP programmers ought to have one of those.

[Reply #4 on:]

Ive been plugging and unplugging with the power on . As long as the programming has finished it does not seem to do any harm. Probably reaching 1000 plug ins and pull outs this way with no bad results.

But then I am more of a risk taker than most

[Reply #5 on:]

Ive been plugging and unplugging with the power on . As long as the programming has finished it does not seem to do any harm. Probably reaching 1000 plug ins and pull outs this way with no bad results.

But then I am more of a risk taker than most

Atmel's AVR chips seem quite robust (read these forums for a while, the abuse is endless). I don't think it's a good habit to get into though, there's plenty of chips that die at the drop of a hat.

If you're only disconnecting the ISP cable then it might not be risky at all. When the programmer is inactive all the connections except +5V and GND are tristated (hopefully!). When there's only +5V and GND it doesn't really matter which one you disconnect first and the effect is the same as a power switch.

When I put the switch in I was more worried about using the ZIF socket when the board is powered on.


(nb. The above is only true if the ISP cable is the only power supply. If you have another power supply connected with common ground (maybe something needs 12V) then disconnecting GND before +5V is very risky indeed. You could easily generate a huge voltage difference between the +5V pin and the other supply's ground, or even a negative voltage). Don't do it.