Attiny85 Programmer/Breakout RevB2 Preview

A little while ago, I posted about some updates to my Attiny85 Programmer & Breakout PCB that showed off a new design with a breakaway Programming section of the board. I threw that out and started over again. There’s still some work to be done but I wanted to show where I’m going with this.

render_frontThis is a render of what the board looks like. The program I use to render places the design on a rectangle so keep in mind that the purple outline would be the edges of the board.

The Power In and Attiny85 have swapped places. I’m going with an SMT LED and resistor for the power indicator to open up some more room on the board (labels are in the design, won’t be printed on the board).

The board is designed so that the Program section would be broken off once you’re ready to use the the board as a breakout. What if you realize later on that there’s something wrong in your code? You could connect up your Uno using the Breakout section, but you’d still need another capacitor for the reset pin on the Uno, and this kind of defeats the purpose of the board. I’m working on an experimental idea to make it easier. The pads next to the Power In area is a temporary programming area where you’d connect the Program section. The problem is making the connections. You can’t really connect the Program section back directly using headers because then you have no way of making another set of connections to the Uno. The best way would be to make the connections on a breadboard. It’s not ideal, but it’s still easier than looking up which pins of the Attiny85 go where on the Uno.

render_backI’ll put a URL to an updated manual on the board again. I still want to get some instructions on the board with the space I have but the small size of the board makes it difficult to put anything really specific. I’m on the fence on whether the text on the Program side will stay (the lines it’s referring to are on the top side of the board, I need to add lines on the bottom side too).

I’ve been making an effort to getting the sizing of text (and traces) right since I made the text on my AMS1117 board a bit too small.  I use mm to design my board, but a lot of help resources and parts of Eagle use mils. I made a table of conversions between mils and mm. I put it up for download as a Word document and pdf in case you’re interested. I got the table from here but formatted it to print.schematicI redid the schematic, chopping it up into sections and adding labels. Everything was directly connected to each other in the first schematic. It was messy, but not having things directly connected to each other does worry me in case something isn’t connected properly. I’m constantly checking connections and working on the other details of the board I talked about above so I’m taking my time. There were people watching the Attiny85 Programmer and Breakout Rev A board on eBay so hopefully that means there is some legitimate interest in these boards. I would like to get them manufactured.

Just a note for people who are Googling around for the warning, “Segment of net [name] has no visual connection”, I deleted the label of that net and placed a new one to clear the error. I couldn’t find much help when I was searching around so hopefully people land here if they run into the same warning.

Anyways, thanks for reading!

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#NoPrototypeChallenge

That might as well be the name of my “Wastebin Project” category. I haven’t done a Wastebin Project in a while so I’m shaking off the dust on this blog category today. This category is for those small random projects that only last for a day. They usually happen without proper thoughtful prototyping. It’s just about getting the creative juices flowing, experimenting, and having fun thinking on the fly.

Anyways, today I wanted to try something I’ve been meaning to do for a while, and that is try to create the smallest mobile robot I can. I also wanted to challenge myself to see what I could come up with in an hour.

I’ve done a couple of mobile robots before. My first robot was “Frank” who won the hearts of many. My second robot, “Greg”, was what I liked to call the Mobile Billboard because it was a rectangular bot with an LCD strapped to it. With my PCB designs that I’ve been posting about for the past little while, I can get a mobile robot to get into an even smaller form. Spoiler: It doesn’t work out, but seeing what doesn’t work along the way was interesting to me.IMG_20140924_154601This was it at the end of the project. If things did work out, I’d swap out the jumper wires for shorter soldered wires to neaten things up. What really was the final nail in the coffin was a wire between the 9v battery holder and my AMS1117 Voltage Regulator Board broke. But that was just one nail, among a few others.

The big thing I learned was that the servo library doesn’t work with the Attiny85 microcontroller because the servo library relies on 16-bit timers while the Attiny85 has 8-bit timers. I’ll have to look into it, but upon some light research it looks like it’s possible. After I realized that, I swapped out my Attiny85 Breakout Board with my Atmega328p Breakout Board. I got the servos rolling, but there was no control or logic behind it.

I wanted to try using a photoresistor instead of the ultrasonic sensor to be the eyes of the bot. I didn’t test the photoresistor so I couldn’t calibrate it. I was just guessing values but none of them worked so I don’t even know if the photoresistor was working at all. I still have the circuit so I can play around with it.

IMG_20140924_155017I kept the chassis because I want to try this again. This is how I always make my chassis but it’s a lot smaller compared to my previous robots.
IMG_20140924_155031This is the photo resistor circuit, as well as the power supply outputs (the headers) for the servos. I’ll play around with the photoresistor and maybe this could be back again in round two.

Thanks for reading! I’m still working out plans for my next project. It should be a light show… Stay tuned!

ATmega328p Breakout Test Results

In my last post, I talked about the tests I did with the AMS1117 Board. Now it’s over to the ATmega328p Breakout Board. The testing was a lot simpler, and included the AMS1117 board.IMG_20140919_121331This was it. The test was just to run a sketch on the ATmega328 microcontroller, uploaded using an Arduino Uno. The sketch was some patterns that used all 17 outputs (the 11 (not using RX or TX), plus the analog in pins used as digital outputs). The chasing patterns made sure that that the pads were connected in order. Here’s a video:

IMG_20140919_154612I used my multimeter to do some other tests. I tested the other pads on the board (RX/0, TX/1, and the Vcc and GND pads) with the multimeter. I also measured the curent flowing between the AMS1117 and the ATmega328 board. The reading in the picture above is from when all of the LEDs are on.

One thing I realized is that the 1A fuse for the uA and mA setting on my multimeter is blown. I went looking for them and the cheapest I can find is a 20 pack for ~$5… The A setting works just fine so I can live with it. The fuse on the A setting is 10A so it should last a while and would be the one I’m more willing to replace if it does blow someday.

Anyways, thanks for reading! I’m still planning out some projects so stay tuned!

AMS1117 Board Test Results

In my last post, I talked about assembling my two new PCB designs. In this post, I’ll talk about the results of some tests with the AMS1117 dual fixed voltage regulator board.

As I was assembling the board, I had realized that I hadn’t accounted for the voltage drop of the diode. It wouldn’t be an issue, except that  I wrote that the maximum drop out of the AMS1117 is 1.3v on the back of the board. Theoretically, there’s a dropout of 2v with the reverse polarity protection diode in the circuit, which is about the same dropout as the LM7805 voltage regulator. I’m glad I put in the diode though, since I’ve accidentally connected the battery backwards a few times already.

Anyways, I don’t have a variable voltage supply so I built an LM317 variable voltage regulator on a breadboard for this test. The test was to ramp up the voltage to see when the 3.3v and 5v outputs would appear so I can measure the dropout.IMG_20140919_101619

You can find my test notes here. Basically, I found that the total dropout with the diode for the 3.3v regulator to be 1.74v and 1.59v for the 5v regulator. I’d round up the total dropout for both to 1.9v, or 2v to make things easier. I chose the AMS1117 instead of the LM7805 because of the lower dropout, but I forgot about the protection diode. I’m still glad I went with it because it reduces the board size significantly, and the SMD soldering is fun.

Test results for the ATmega328p Breakout Board should be posted soon. It was a pretty basic test, which it passed. Yay.

Thanks for reading!

New PCBs! (AMS1117 regulators & ATmega328p breakout)

I’m excited to finally have my second round of PCBs here! The designs are an AMS1117 regulator board and an ATmega328p breakout. I already have notes to share from soldering one of each to start testing them. The notes in this post are just from assembling them. I will have a separate post that goes into detail about my tests with them.IMG_20140918_193548This is how the boards were designed. They are meant to split apart easily with the tab between them. I got a little excited and went for it without scoring it first, so I destroyed one ATmega328 breakout since the weakest points in that area are the pin pads 2-4. No worries though, I got a few extras in this batch of PCBs, probably because they don’t take up the complete 5x5cm area I have to work with. I tried splitting another board by scoring both sides with a knife and they split cleanly without damage to either design.IMG_20140918_193021This is the AMS1117 board that has two fixed voltage AMS1117 voltage regulators. One produces 5v, the other produces 3.3v. It is a tight squeeze because the capacitor footprint is smaller than the actual capacitors, but it doesn’t seem like it’s an issue. On the back side is a note, written in text that’s a bit too small, that the dropout is 1.3v so you have to supply it with at least 4.6v for 3.3v or at least 6.3v for 5v. I forgot to include the drop of the diode which should be 0.7v, but most applications would probably use a 9v battery as the input to this board. It will be part of the testing, though 1.3v is the maximum dropout so results may vary between the regulators. We’ll see how the tests go.

It was fun placing the SMDs and trying to align them properly. It bugs me when my components end up in some awkward position so I feel the pressure with these small SMDs. I got to solder SMDs back in school where we used a flux pen, solder paste, and a toaster oven. I have none of those things so it’s hand soldering for me.
IMG_20140918_192836This is the ATmega328p breakout board. (The crooked oscillator is bugging me.) I really bumped my head with that terminal block for the power input. The terminal block I used on the board is 3.5mm while I’m sitting here with 5mm (0.2″) terminal blocks, which are the ones found on my Attiny85 board. It’s not a big deal as I can always go and buy them, or I can just solder wires like I did with this one.

The boards have proven to be functional, together no less. Again, full test results will be coming up shortly. Stay tuned! Thanks for reading!

Brainstorming for Fountain Show 1.1

IMG_20140917_135652Ever since I wrapped up the first fountain show, I’ve been trying to come up with ideas on how to improve the show. The focus of the next stage, if it ever gets off the ground, is creating some kind of backdrop. I found that there were too many times where the stage was completely dark so a lit up backdrop would fix that, in addition to opening up more kinds of lighting effects which, as it is right now, is limited with just 5 fountains sitting there.
IMG_20140917_120624This is probably the easiest upgrade I can do because it doesn’t involve setting up any vertical elements like my other ideas have. It’s basically lining the basin with RGB LEDs which would make for some cool chasing patterns, but that’s about it. It’s not the idea I’m likely to go with but it’s a cheap option.IMG_20140917_120631This idea would be kind of a spin on Light Show 3 with the lit up towers, except that they’d be horizontal.

The issues I’m having are coming up with materials and figuring out how I’m going to set things up. I don’t have an abundance of cardboard any more so I don’t have the materials to make the backdrop. The original set up was somewhat temporary. I’d leave the basin filled with water, but I’d put it on top of a table to avoid bugs on the ground in my basement. I don’t think I’d be able to do that with a backdrop attached to it so I may end up building it completely separate of the basin. We’ll see.

I was contemplating putting the fountain show on a hiatus until next spring, but Halloween is coming up and I’d like to do some kind of LED project for it so it could be a Halloween themed fountain show. I always end up waiting until the last week before deciding to do something. If I can’t figure out a plan for the fountain show, I may just have to put it on hold and go back to my “traditional” light show, or something else completely, for Halloween. I also have plans (not on paper yet) for Christmas that’s separate from the fountain show. So yeah, the fountain show is in bit of a limbo right now.

Thanks for reading!