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Input Devices

Temperature

I still want to make a pancake printer for my final project, I'll simplify to just 2 dimensional and in light of this assignments exposure of my horrible, yet improving, skills with electronics I might just have four preset shapes you can print. Of course those shapes will be turtle, dolphin, narwhal, and triangle. But I need to know how hot things are, and by things I mean the extruder, the griddle, and the elctronics next to all these hot parts so I need to have a temperature sensor. I'm tempted to build a mechanical solution, but as scary and hard as electronics are I want to know how to create them. So I chose to make a temperature sensor. More specifically I decided to create a derivative of Neil's temperature sensor that's on the class website.

Who Needs Eagle When You Have Illustrator

I was out for most of last week and had to make a few simplifications to catch up on both this assignment and the molding and casting assignment from last week. The first simplification I made was drawing my circuit instead of cadding it on Eagle. This might not sound like a simplification or a good idea, but I'm more familiar with Illustrator so it sped up my process and really taught me a lot about how Eagle works. I started by getting to scale images of the traces for individuals parts into Illustrator. I then grouped these images together and gave them their proper names in a master document containing all the parts I'd need. It was actually tons of fun and I learned about layers in Illustrator and how to use those and how to set names for groups. There's a tab on the right side that says layers and in it you can make layers the sameish way you would in Eagle and you can toggle their visibility to export just the layer you want. After creating a library of parts in Illustrator I looked at the size for my routed wires and copied the size into Illustrator's pen tool so I would be creating lines of roughly the same size but a little thicker because of all the problems I've had over the semester with tiny traces, I found that it correpronded to lines roughly 1-1.2pts thick. Then all the was left was to connect the neccessary pieces together which Illustrator made super quick and easy, and I forgot to mention this but you can also name elements in a group so for example I named both the group of connections for my Attiny45, tiny45 and the individual pins with the names given for them on the data sheet. And I got to make cute swirly lines (that the mill hated but I like) instead of straight ones. All together a win win win, and I easily made a cute shape for my board.

Milling and Soldering: AKA the part where everything goes wrong

To make a long story short the mill wouldn't connect to the computer and it took me hours to figure out why but with a little course 6ing I figured it out and fixed the problem. I'll write it here for future generations or Archshoppers. The deviceserver file was in the wrong location so when you type in the code to connect to it you get a "not found" error. You might want to search for it yourself to confirm, but I found it in the modules/js folder so instead of typing "node deviceserver.js ::ffff:127.0.0.1 1234" you type "node modules/js/deviceserver.js ::ffff:127.0.0.1 1234" and if that doesn't work you close out and type "sudo chmod a+rwx /dev/usb/lp0" changing the /usb/lp0 for whatever it may say in mods. Then it will work... you're welcome. After that milling went smoothly and I had my TurtleTemp board, but apparently turtles are rounder so it's a TortoiseTemp board but I don't listen to the haters so it'll always be a turtle in my heart. Soldering also went really smoothly and is hardly worth mentioning except to say that the tips of the soldering iron don't work if they're really burnt and dirty.

Oops: AKA I was being dramatic before but here everything everything really went wrong

To make a long story short I used the wrong template circuit and made the helloload board for step response, luckily my handy Illustrator library saved me and I quickly editted the layout and remilled (I started it up correctly immediately so it went a lot faster). I was rushing a bit and had to use an exacto knife to fix some traces that had combined, I didn't mention this before but I took minimum distance down at the start so my lines would never be too close. Finally I had a working TurtleTemp board. Now for the hard part.

Coding and Understanding

Thanks to a lot of help from Anthony I now understand the board. It uses a wheatbridge which acts like an op-amp to amplify the difference between the voltage between two 10k ohm resistors and a 10k ohm reisistor and the sensor which is nominally 10k resistance but that change by very small amounts with the temperature. Temp increase=resistance increase, temp decrease=resisance decrease. I was not however able to get my board working because of the microcontroller, Attiny45s are ancient and aren't easy to use with current technology. I had to run it through the Atmel-ICE whilst powering it form the other side. I also had to search the deep crevices of the internet for an ATtiny45 arduino board setup. First I got a you nees a programmer error, then I pressed ctrl+shift+u which means upload with a programmer, then I got a board not found error, I switched the wire around and still no luck. I hope to fix this later, but the best solution is honestly just to use a better microcontroller, one that can interface with USB directly.