Shrinking Arduino Projects using ATiny85 update

Introducing the ATtiny85 ISP! -a breakout prototyping board for ATtiny85/45/25.

Previous version Shrink your Project

The ATtiny85 ISP! is an open source, Arduino IDE compatible hardware project, that uses the ATtiny85. Port your smaller Arduino projects to a cost-effective platform with ease.

Specs:
Easy to use 6-pin AVR ISP header (for use with many ISP programmers or Arduino itself as an ISP)
Open Source Hardware!
Use with standard Arduino IDE or AVR Studio
Allows FULL use of the 8K memory on the chip (no bootloader needed!)
All pins broken out for use, none restricted
LED power light informs you that the board has power
Reset button on board
Easy to assemble due to through hole construction
Easy to replace chip if you "let the white smoke out"
Also easy to take your programmed chip and put it in a final more permanent project
Able to use external crystals, resonators, or none if you wish
Small enough/inexpensive enough to be left in a final project
How it all began:

I love the Arduino and while Arduino is powerful, some projects just don't warrant the power (and cost) of a full fledged ATmega328. If you need to make a temperature sensor that connects to an LCD and clicks a relay, the ATtiny85 is more than up for the task. Want to run a few LED's, or an RGB LED...no problem. I needed a solution that can be used to prototype and also take the final prototype chip and embed it in a project. Simply pop it out of the ATtiny85 ISP! and you can embed it in your final project.

As I became more and more involved with Arduino, I saw the immediate need to actually bring my Arduino projects onto a breadboard. Breadboarding is a great way to easily change and tweak your circuit and prototype quickly. When I first was using the ATmega328P on a breadboard, I thought to myself, "how can I make this project smaller?" Delving deeper into the world of Atmel's ATtiny chips, I saw the true potential of this tiny series and the idea came to me to try and make it easy to use for existing Arduino users to use.

The problem is that trying to program a bare ATtiny85 looks like the picture below. Also you need to remove the chip from your connected circuit each time you want to upload a new sketch.



Working with a bare ATtiny85 is a hassle!

Following cues from other projects that brought the ATmega328 to a breadboard, I hit my CAD software and was able to construct a few prototypes which originally looked like this:

This was a good start, but I really felt a power LED indicator were a good thing to have. Additionally, some refinements to make it dead-simple to solder were now in the works. I was thinking about using a power jack and onboard regulator, however most ISP programmers have 5v power and ground right on the connector. That means most simple projects do not require a power source when hooked up to your programmer (the programmer supplies power) as the programmer will get +5v off the USB port. The result is that I could make it smaller, while still retaining useful functionality. Smoothing capacitors, reset button, ISP headers, and a power LED are all right on board in a very small package.

ATtiny85 ISP! in action:

My idea is to allow Arduino users to take advantage of the ATtiny85 chip's potential while using the familiar Arduino IDE (and super awesome support from the Arduino community). Lots of existing Arduino code ports over easily, and where it doesn't there are special libraries (TinyWire, I2C LCD etc) modified for use especially with the ATtiny series. When I first started exploring the options of using ATtiny85 in projects, there were a few challenges to get the chip to work with the Arduino IDE, however the most challenging for new users is the physical wiring of the ATtiny85 chip itself. There are just so many wires that have to be put in the correct place each time you want to program. ATtiny85 ISP! solves that problem, and makes it easy.

I did some basic research and it is a fact that there are some other ATtiny85 boards out on the market and I must say they are simply great. The main common theme I kept seeing with these types of boards is that they use USB to make it easy to connect to a computer. This is great, but the underlying issue is that by using onboard USB to load your sketches, you need a bootloader which resides in the flash memory of the chip. The bootloader takes up around 2K of precious space on the ATtiny85. Since the ATtiny85 only has 8K of flash for sketches, this is 25% of your total storage! This is not acceptable to me to lose a quarter of your available space when you only have 8K to start with. Every byte counts!
Some ATtiny85 boards require a bootloader...that means 2K you can't use

ISP programming is the remedy to this solution, and does not require a bootloader. This gives the user full access to the flash memory on the chip for sketches. It also makes it easy to change the clock speed or set custom fuses for special applications.
Easy to Build!

I considered surface mount construction, however the layout wouldn't have been much smaller. I ended up going with through hole components allows just about anybody with even mediocre soldering skills to assemble the ATtiny85 ISP! Also, through hole construction allows easy replacement/swapping of the chip itself.

Assembly of ATtiny85 ISP!

Through-hole also makes it easy to replace a damaged ATtiny85 chip (in case you let the white smoke out...) or to take your final project chip out of the board and place it into its more permanent home.
Open Source...for life!


Open source hardware is a huge part of the Arduino and it's all about people helping people. This is a great concept and the ATtiny85 ISP! board will be available for everyone. The goal is not to make money, but rather bring the ATtiny85 capability to all Arduino users. All design files and schematics of the ATtiny85 will be immediately released to the public upon successful funding of the project goal.
Where are we at?

We are pretty much done with the R&D. Final prototypes are made and verified working. The last thing is that colors of the final PCB board and power LED are subject to change. Let's see where we are at:

Prototyping....DONE!



Design and testing...DONE!

ATtiny85 ISP! running an I2C LCD display

The latest prototype revision board works, and it works great! What is left is to get a bunch of them made and get them out to the Arduino community. That is where I need your help.  The different levels of pledges will allow users to get anything from a bare board, to a complete working board ready for you to prototype with and get started shrinking your favorite Arduino projects to the ATtiny!
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