Atmega328p Breakout PRO

The Atmega328p Breakout Board has been out of stock for a while. I have half of the new components in hand, and the PCBs have been shipped and are on their way. The rest of the components will be ordered in the next couple of days and, if it’s like the last time I ordered, it will arrive the next day. Friday is Good Friday so I have to keep that in mind, and hope that everything comes in by then. I’ve made the decision that I will no longer sell unassembled kits so I hope I can use this long weekend to put them together so I have a decent stock ready for the next week.

Anyways, while I’ve been waiting for the new batch, I’ve been working on something else…

draft1To the right is the first draft of the Atmega328p Breakout Pro. The current base version will likely drop the ISP header. The new Pro version will sport the ISP header, in addition to a voltage regulator circuit. As I talked about in the last post about voltage regulators, I’ve been using my AMS1117 voltage regulator boards with my Atmega328p Breakouts in my own projects. With the built in regulator on this Pro version, I won’t need that extra board. The regulator I’ll be using this time is the NCP1117.

I believe the NCP1117 is the same regulator as the one on the Uno, or at least similar. It can output a fixed 5v at 800mA, even though at 800mA it’s best to just use another supply if you’re driving things that need that much current. When I was learning about PLCs, I was taught to separate the power supplies between the control unit (the PLC) and the actual peripherals (sensors, indicator lamps, etc). I don’t see why that lesson can’t be applied to Arduinos, even if they draw less current than a PLC.

I’ve added in the reverse input voltage protection diode so the total drop out is roughly 2v, just like on the Arduino. You’ll need to supply it at least 7v to get the 5v, and I’d limit the input to 12v tops just because of heat dissipation.

I’ve been trying to find out if it’s acceptable to have an external voltage applied on the output of the regulator. I want to be able to apply an external supply to Vcc (the output of the regulator, and the input power supply of the microcontroller). That way, you could use a battery or supply that’s already in the operating voltage range of the Atmega328p (1.8-5.5v). I’ve been looking at some Arduino and Adafruit schematics and it looks like you can, if you consider USB Vcc as an external 5v supply. They have it connected to the same 5v net as the output of the regulator (although the Adafruit schematics use a different regulator). I’ll keep researching and probably put together a prototype demo circuit and see what happens.

That’s it for now! Thanks for reading and I hope you’ll stop by my Tindie store and pick up some of my Atmega328p Breakout Boards when they’re back in stock!

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Let’s talk regulators

IMG_20140918_193021As you probably know by now, I have released a few of my “old” circuit boards for sale on Tindie. Actually, they’re all revisions of previous boards I’ve shown off on the blog before. The one board you have not seen revised yet is my AMS1117 3.3&5v fixed voltage regulator board, pictured on the left. I’ve been looking over the design, while also straying away from it looking at other low drop out (LDO) regulators.

Functionality of the original board was not a problem. I still use these boards for prototyping and testing, and also in my final project builds like in my 24/7 powered ESP8266 project. The worst part of the board are the capacitors because they’re so close to everything else on the board including each other. I didn’t leave enough room between the larger capacitors so they’re awkwardly pressed up against each other. It’s so bad that I used hot glue to keep them solid in place because some of the capacitors aren’t sitting flat on the board. This can be easily fixed in the next revision by moving to SMD parts, which has been the plan for all of the boards since I decided to revise them all.

IMG_0767With the drop out voltage of the diode (reverse input voltage protection) and the regulator itself, you’re required to supply at least 7v to get 5v out of it. That’s the same thing as everyone’s favorite LM7805 which has a drop out of 7v, without a protection diode which would add another ~0.7v to the total drop out of your regulator. With that said, I pretty much only use 9v batteries with my AMS1117 board because it meets that minimum input voltage without being too much over. I have the ESP8266 project powered 24/7 so I’m obviously not using batteries but a 9v wall power supply.

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SPX1117 schematic in Eagle – “Improved Ripple Rejection” circuit from datasheet

Speaking of wall power supplies, it introduces another “issue” if you use one with a voltage regulator. I don’t own a bench power supply or oscilloscope so I can’t get down into the fine details of  better monitored current draw or frequency response. You don’t have problems with frequency response with batteries because they output a solid DC voltage. However, with wall power supplies, the power from the wall is a rectified sine wave which is bound to have ripples in the output. I’ve been considering the change to the SPX1117 regulator which has a circuit in the datasheet to reduce the ripple… but then I wonder how much this actually matters to anyone. For hobbyist projects which is what these boards are made for, it’s really not going to have any major affects to it, as demonstrated in my projects that have worked well with the regulator board for extended periods of time.

I’m not really sure which regulator I’m going to go with. The main reason for looking at the SPX regulator is because they’re more readily available from my go-to suppliers than the AMS regulator. I may even just put the regulator circuit on the boards that would need them, like the ATmega328p breakout board. That’s the biggest motivation for designing these regulator board anyway. In that case, I probably wouldn’t need a regulator that can put out as much current (800mA)… We’ll see! Thanks for reading!

Debut [of sorts]: “How we do it”

The light show that never was… Enjoy these 15 seconds!

Another scrapped #arduino light show…

A post shared by Matt (@mwhprojects) on

The challenge of this one was to see what I could come up with using my updated shift register boards (which are available  on Tindie!). In the previous light shows that used my older shift register boards, I couldn’t use any PWM because those boards didn’t have the Output Enable pin broken out to use. My new ones do so I really want to see what I could do with them. Each color has its own shift register board, with an extra shift register board dedicated to all colors of the LEDs attached to the servos. I like some of the effects I made up and I hope to continue working on it so I can come up with something better with another song in the future. It’s “How We Do It” by Lights, by the way.

Thanks for visiting the blog!

Maybe I just need to market better

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My ATmega328p Breakout Board was featured in a Tindie email newsletter. As soon as that email went out, orders started coming in, including one that picked up all 30 assembled boards that were in stock at the time. It sold out in just 24 hours and I’m currently in the process of restocking it. At the time of this post, the PCBs are being manufactured and half of the components are on their way. I’m planning on assembling the majority, if not all, of the boards before they’re put back in stock. I’d estimate them being back in stock within the first couple of weeks in April.

My other products on Tindie haven’t had as much interest. In addition to more Atmega328p PCBs, I also threw in a simple LED bar PCB that is specifically designed to work with the shift register boards. There are 16 individual SMD LEDs in a row. They’re all numbered so it would be a great tool for debugging and as system indicators in your project. I hope that bringing three of my products together (shift register board + LED bar + Attiny85 Programmer & Breakout) will spark some more interest in all of them.

A quick Saturday programming project: VB Converter

After the attention my Tindie store had recently, I ran out of envelopes. I was thinking of ordering a bulk of envelopes and supplies from Uline in the hopeful case that my store continues on. The Uline site uses inches which I don’t use often because I’m Canadian. I found that having tabs open to convert the length and widths of different products was getting too cumbersome so I decided to write up a quick program in Visual Studio. It turned out to be a whole Saturday of overthinking it. It happens every time I program in VS…
screenshotIt originally started with just the small conversion window but since I was converting two values at a time (lengths and widths of envelopes), I wanted a way to save those conversions so I could see both values at the same time and compare between different sizes. That’s where the History & Saved window came from. It uses My.Settings to save a few things, including up to 6 conversions.

It currently does conversions between inches and centimetres, and mils and millimeters (I use millimeters in Eagle). That’s all I really need right now. It shouldn’t be too hard to add more conversions later on if it’s ever necessary.

Check it out on GitHub if you’re interested in trying it out!

New products you already know

Yesterday I released two “new” products. They are both revisions of projects you’ve seen on the blog before.

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They are both the second revisions. They are the Attiny85 Programmer & Breakout Board and the Atmega328p Breakout Board. They’ve both been completely redesigned (ie. manually routed this time) with new features!

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Remember this clunky old thing? This is the original Attiny85 Programmer & Breakout. I really wanted to go for something more compact and breadboardable.

1I really like how the new one turned out because my measurements worked out! The board can sit on the edge of an 830-point breadboard so that the programming and breakout pins fit into the prototyping area, with the input power pins fitting nicely on the side power rails.

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To the right is the old Atmega328p Breakout. There’s not much change to the way it looks but the new board does have a few nice changes to it.

1The new board now breaks out the reset pin so that you can add an external reset.

Both boards now have LED power indicators, SMD components, and 6-pin ISP headers.

Head on over to my Tindie store to check them out!

So that’s what’s been going on. I’ve been meaning to do a new light show (possibly sans fountains for now). I mostly just want to use my new shift register boards with the PWM control it now allows… Stay tuned and thanks for visiting!