Jar of Fireflies

Step 14 Final Assembly

By this point you've completely assembled the circuit board and attached the LED strings and battery holder.

All that's left is to program the chip and affix the board assembly to the lid of your jar.

As to how to program the chip, I'm afraid that's a bit beyond the scope of this document and is heavily dependent on what platform of computer you're using and what development environment you're working with. I've provided the source code (written for GCC) as well as compiled binaries but figuring out what to do with them is up to you.

Thankfully, there are loads of good resources out there for getting started with AVR, here are a couple:

http://www.avrfreaks.net/ - This is the penultimate site for AVR. The active forums are indispensable.
http://www.avrwiki.com/ - I found this site quite helpful when I got started.

If there's sufficient interest I may put together a kit so that people don't have to get their hands dirty with the chip programming aspect.

As for attaching the board and battery to the lid, there are probably a million ways to do this but I'm not confident that I've found the best one yet. The methods that I've tried have been to use either epoxy or hot glue. I've already had a few instances of epoxied boards pop off so I wouldn't recommend using that. Hot glue seems to work ok but I have little faith that after a few hot/cold cycles it'll fair much better than the epoxy.

So, I leave figuring out how to attach the board and battery holder to the lid up to you as well. However I will offer a few tips:

-- Be careful that when you attach the battery holder that the two pins don't short out due to the metalic lid. Some lids are insulated, others aren't.

-- http://www.thistothat.com/ -- This is a website that offers glue recommendations based on what you're trying to glue. For glass to metal (the closest approximation I can think of for silicon circuitboard) they recommend "Locktite Impruv" or "J-B Weld". I haven't ever used either.

Comments

[Wilbur_Nether]

There is also that double sided mounting foam, which might work pretty well to mount the circuit board and battery holder.  This would probably also help insulate the battery holder from the lid as well.

By the way, I used Lady Ada's USBtinyISP to program my MCU along with AVRdude in Ubuntu.  I'm not sure what the actual correct settings should be used for the fuses though.  I used Low: 0x62, High: 0xDF, Extended: 0xFF.

[nolan_777]

I found there to be some lacking details as far as the programming of the attiny45. The details in this project to not note the clock speed of the processor to set. Or ever the programmer used, just a picture. Also have had issues with programming the chip via the hex file and AVR Studio and the AVR DRAGON. Can program the flash just once, after that, can't do anything with the chip, of course the programming fails!. Any thoughts would be helpful.

[f.l.u.x]

Keso, props for a very well done instructable. High level of detail and great pictures. My two cents. From work experience, I've got a suggestion for the type of adhesive to use. On our medical device, we use LOTS of "3M VHB" tape. There are varieties, but the one I like most is the #4910. It is essentially pure adhesive in a tape form. In other words, it's not tape with an adhesive agent bonded to it, but the adhesive itself as a thick jelly like substance able to stick to anything and fill itself into uneven surfaces. We use it to bond G10 (PCB material) to aluminum, for example. It is so strong and durable, there is very little hope of safely pulling the board off after you've set things in place. There is no cure time by the way- the adhesive sets immediately. For those using McMaster-Carr to order things, here is the part number for the 0.5" wide adhesive: 76665A84 - f.l.u.x

[ccarlson]

I used Lady Ada's USBtinyISP to program the ATtiny45V for this project, and ran into a small snag when trying to reprogram a chip that was already in a working circuit.

What it boils down to is this: When programming a chip that's already soldered to a finished circuit, don't let the programmer power the process via USB--remove the jumper and install a battery in the firefly circuit, instead.

(Thanks to Lady Ada herself for discovering the solution for me!)

[jason]

You might try an adhesive generically known as "silicone rubber". It's a non-conductive gel that sticks reasonably well to most things. Once dry it's semi-flexible (about the consistency of caulk). The down side it that it takes a few days to totally dry.