I've got a couple of 328ps but couldn't get them to work. Need to try again.

They're pretty easy to get working. Everything on that board will get it detected by AVRdude. You do need a USBasp to program it or upload a bootloader if it doesn't come with one.

But it should have have some caps and resistors and other bits to properly connect it all up.

I think I've got some of the correct caps and a ceramic resonator but couldn't get it working last time.

Still cheaper to buy an Arduino nano though!

Maybe it's cheaper to remove a load of the voltage regulator bits off a pro mini.

Really? Cheaper to buy a fully assembled board than a single chip? How much do you buy nanos for? My 10 Atmegas cost £20 so £2 each.

I did try disconnecting the voltage regulator and power LED from a mini but couldn't get the power consumption down far enough. Much easier with the DIP chips if you want to go low power.

I bought 5 Nanos for £9.57 early this year. £1.91 each.

I think if low power really is essential then the chip is the way to go.

Looks like you can get 10x nanos for ~£16 now.

Possibly even cheaper if you searched a bit harder - http://www.ebay.co.uk/itm/181880011056

Just found 10 pro minis for under a tenner.

http://www.ebay.co.uk/itm/201419551076

Wow, that's crazy cheap. How much do the official ones cost compared to that?

Cheapest I can find the chips on their own is about £1 each. No caps or crystals with that though. My other ones came with all that sfuff but I don't use them, and a DIP socket and reset button.

They're so cheap I pretty much see them as disposable now.

I might see what sort of power a pro mini uses with regulator and all LEDs removed. No USB chip to consume energy either.

Not sure if I posted this before but http://www.gammon.com.au/power is very helpful for power saving.

I have seen that before, but forgot about it!

Soldered up another board with a Li-Ion battery now. It's powering up but not sending the temps for some reason. I'll have to try and fix it tomorrow.

What's it all going to do in the end?

/Exciting stuff/... display a graph.

Screenshot attached of the current one doing its job in my living room. With other bits for turning my water and heating on.

Finally got round to changing my loft door over to reed switch from hall effect sensors. Open and close switches to prevent closing too far or opening too much and killing the motor/winder.

Whilst I was doing it I killed the original arduino, lovely smell of something electronic going pop. I had stupidly soldered the nano directly to the board meaning I couldn't swap it out easily. Tried to unsolder it but it wasn't budging. Ended up making a new board and added female socket headers so I can swap it out and reprogram without disconnecting the whole board.

 (bounce)

Nice work :) What do you use to activate the door? I think you did say. I've realised it's not goot soldering some parts in just in case they need changing. In fact the reason my temp sensor didn't work last night was because the actual temperature sensor on the board has stopped working.

It's made me make some changes to the software though. Before I was manually inputting the DS18B20 address before flashing, I had to reflash if I wanted to change the sensor. Now it finds the address automatically and lights the LEDs if it can't find one.

I've also changed the sensor interval to 5 minutes from 1 so should save 5 times less data now. Too many points on my graph I think.

So I finally have 2 working sensors. Have to decide where to put this one and also change the software on the Pi so it can show data from more than just one sensor.

My two boards side by side.