Ambitious ATtiny85 Board Tests a Beginner’s Skills

[Chris O’Riley] has been playing around with Arduinos for around a year, and decided he wanted a breadboardable ATtiny85 in order to prototype using the actual controller that would be used in the final project. He wants to use it to interface with a Bosch BMP280 pressure sensor, but for now it stands alone.

It’s a simple board with the Tiny85, 3.3 V and 5 V regulators, a power LED, as well as the usual resistors and caps [Ed: not resistor sand caps]. The double-sided PCB [Chris] milled himself — he’s an illustrator and photographer by day, so it’s no surprise the board turned out gorgeous. He designed the board in Illustrator after taking a stab at Eagle, then ran it through his CNC to mill the circuits using a .017 inch end mill as well as drilling the vias. He add solder paste using the tip of a knife, but after messing around with an iron, he ended up investing in a hot air rework station.

We love our Tiny85s here on Hackaday. Check out the ATtiny85 gaming console, the NTSC-generating ATTiny85, and making DIY I2C devices with the chip.

31 thoughts on “Ambitious ATtiny85 Board Tests a Beginner’s Skills

        1. I’ve gotten them on eBay and Amazon and they seem ok. For these, I generally buy the cheapest ones I can find since they snap so easily. Keep an eye on Amazon, every once in a while they have them real cheap, I was able to buy 4 of them for about $5 each.

          1. I have some ebay cheapos and tried to shorten one to cut down the run out and a dremel cutting disk had a hard time on them. must be made of something good.

    1. I’m still going to learn Eagle or another suitable program, but milling the board myself, I had some limitations (distance between traces, etc.) that I couldn’t figure out how to configure in Eagle. And as I wanted to make progress on the board itself, I just went with what I knew. Sometimes the best tool for the job… is the tool you at least know how to use!

    1. It’s not for the LED, but for other things that I’ll ultimately be powering off the 5 volt regulator. The datasheet for the regulator indicated a 1uf cap was needed to smooth the output. I couldn’t fit it on the bottom right next to the input, so I put it on top. Areas like this is where I probably break generally known best practices of electronics, and why I readily admit my lack of knowledge!

      Is there a problem with doing it like this? I could always extend the board so as to fit it on bottom, I was just trying to keep it as small as possible.

  1. The PCB itself is beautiful. Nice art!

    ATtiny85 boards can be found on eBay for about US$1.50 (including shipping). They are “solderless breadboard” friendly, except for the power and ground pins. Search for “ATtin85 Digispark”.

    Peace and blessings.

    1. Thanks! I have some Digisparks and a few Olimexinos. My ultimate goal is a single integrated board with the Bosch pressure sensor and a few other odds and ends. The plan is for an automatic release system for a parachute. I’ve made my 8 year old son little parachutes to throw, and it’s always hit or miss getting them to open just at the right time. With the controller, I plan to have it continually read the pressure as it’s thrown, and trigger a servo when it detects the pressure starting to increase. So, a single integrated board to go inside a small case to attached to the parachute. This way, no matter how high it’s thrown (high when I’m throwing it, not so much when he’s throwing), it’ll open at the ideal height.

      Also, I enjoy the challenge of making stuff, and it’s been a good project to interest my son in electronics. It’s not a field that I’ll ever be particularly proficient in, but exposing my son to it at his age is good.

  2. Just a maker-to-maker tip for the next time, Chris: DO learn a CAD tool (KiCad, Eagle, etc), it pays off on more safe and well-designed clearance and spacing rules; as a bonus it gets more shareable and editable with the community

    1. I totally agree, and it’s a longer term goal. I started to get the basics of Eagle, but as I usually only get a few hours at a time to work on projects like this, for now, Illustrator gets me further down the road at the moment. But yea, learning a proper PCB design program is on the list.

      1. I’d give KiCad a try, it’s a bit… quirky. But it’s pretty beginner-friendly in my opinion and once you get the workflow down (schematic –> footprint association –> netlist –> PCB –> Gerbers/other mfg format) and figure out how to make your own libraries it’s pretty intuitive.

    1. The bottle is covered with icons of flames and skulls, so yea, it’s probably not terribly nice stuff! All the boards I’ve made so far have been small enough to fit through the neck of the bottle, so I’ve just hung them in and it only takes a few minutes. It says to pour it into a plastic container to submerge the board to tin.

  3. I recently finished a project with the ATTiny85 and BMP280. Had to interface them over SPI and wrote some minimized libraries for the ATTiny. Am going to open-source them, but haven’t gotten around to it yet. Let me know if you’re interested, then I’ll bump up the priority.
    Nice board!

    1. I would definitely be interested. I have the code working with an MPL115A2 sensor board that I made and a Digispark using, I believe, the Adafruit library. They (Adafruit) and Sparkfun sell BMP/BME based sensors and I assume have libraries for those as well, I just haven’t gotten to the point I’d need to verify that. Memory is at a premium on the little Tiny, so yea, if you’re willing to share, a minimal library would be great!

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