small footprint arduino nano with usb charging circuit (li ion or lipo) that can turn itself off (soft latch power) - small lithium ion battery

When I started my first Arduino project I realized I needed to use a small one
Format the Arduino so that I can put it in my device.
As a newbie to Arduino, I didn't realize all the challenges in battery management!
After a few weeks of testingand-
Error, read some "my stuff" and watched how
For the video, I came up with a solution that I thought was great and I wanted to share --
Both hope it helps others, and also hope you have some good ideas on how I can take it to a new level.
The basic idea is simple-
I need an Arduino, and a rechargeable battery and battery management with a relatively small and flexible format, easy to build and easy to troubleshoot and modify.
More than the prototype, less than the final PCB.
My solution is not the only one, the process I go through to solve this problem is personal --
Your will be different, and before you find the right solution for your project, my "visible" may be one of the many people you will read.
Material: For the purposes of this note, I assume that you are already familiar with it: assuming there are normal safety warnings about electricity and welding here, you will find these warnings when you study these topics.
Also, one thing I want to point out is that any lithium ion or lithium polymer battery will issue a warning on the box when it is shipped.
If you don't properly handle or abuse them enough, they burn up in a violent way.
If you charge them too muchbeyond 4. 2V)
, Or use a voltage below its minimum recommended voltage (3. 0V)
They may deform and catch fire.
If you're curious, search youtube for lithium-ion battery explosions.
The circuit I'm introducing here has a component that manages the charging and discharging of the lithium ion battery model I'm using here, theoretically preventing overchargingand under-
Voltage conditions, but you should do your own research before proceeding to get comfortable levels with this technology. Adafruit -
Choose the right battery for your project. and low-
Voltage protection for each device I build before I have unsupervised use.
After a lot of attempts and mistakes, I ended up with this design and I wanted to share some of the learning process I went through and the design I completed.
Power the first Arduino project in ArduinoMy using a 9 v battery directly connected to the standard
Size of Arduino Uno.
This works well during prototyping, but the final result is not for anything.
Also, I quickly found that the 9 v battery was not as long as I thought.
Next I try to use more batteries.
I bought a battery stand that can hold 8 AAA batteries and I figured out how to connect it to my new Arduino Nano.
While I could fit it into my project, I was really surprised to find that it didn't have a 9 v battery long to use.
After scratching my head for a while, I found out that this is because Arduino only needs 5 v, and anything above 5 v is "burned" by something built in --
In the "split" input voltage and release any Heat about 5 v under any wattage the Arduino draws from the battery-total waste!
Since I like RC cars, I am on lithium polymer (Lipo)
Battery and use 1-cell (1S)
Lipo delivered from 3. 3 -4. 2V.
After doing some researchMainly Google search)
, I found a 5 v power regulator with 3. 7V (average)
Output from the battery and convert it to the 5 v required by Arduino.
To use the Lipo battery I know I have to have a low battery
Voltage protection circuit.
I studied for a while and found the Tenergy lithium ion battery protection circuit.
I used this in my next version of the project and while it works fine, I was not happy with having to weld the connector to the pad and soon found it no longer available.
When I started working on other protection circuits, I learned that most people are using a charging circuit that also prevents low voltage for lithium-ion batteries.
I ordered these from eBay and converted my project, but I was worried about using them on my 1 s Lipo battery.
I did more research on the common use of charger modules, learned about 18650 batteries and decided to give it a try as they are a more friendly form factor, can easily get in and out of the project, allow me to use my own connector, the charging module is specially designed to use the battery
This gives me comfort that my project will not catch fire! Total Turn-
In the same time frame, I also realized that Arduino was generating power all the time, and when someone pressed the button, my target project at that time ran for a fixed period of time and stopped when it timed out.
I think it would be great if Arduino was able to turn off completely!
I went back to Google, where it would be different to know to search for the right words!
It took a while, but I know what I need is a soft
Lock the power circuit.
This circuit uses an instant button to "lock" the power supply.
By properly integrating with the Arduino, the Arduino program can be completely turned off using one of the digital pin "signal" power circuits-
Zero consumption on the battery.
The only problem is that these circuits are relatively complex.
Especially someone like me who has never designed a circuit.
I did figure out how to build one from a video tutorial, but in the process I also found that one made by Pololu was better than anything I could build.
With these concepts in mind, I showed you my (current)final design!
Please see the attached design image, which number matches the list below: again, after a lot of attempts and errors, I found a build process that fits me.
By soldering the female head pin to the prototype PCB board, all components are simply "plugged in" and All My Circuits are soldered to the bottom of the board using coil magnet lines.
You will notice in the prototype image here that there are several additional titles on the motherboard that the main components do not use, and in my final project design, these are used to hold diodes and resistors, I will not discuss it here.
I like to use headers for all components, because it's very simple to swap components or recycle components when I finish the project.
The attached drawing shows the layout of the head pin and the wiring diagram along with the circuit in the previous step.
Note that the drawing is drawn from the bottom of the angle of view of the plate, which is the angle of view that I often use when welding the head and wires in place.
Wire the coil magnets in length with enough leftovers so you can wrap them around each other without welding other wires.
With a razor or thin-
Sand sandpaper strips the coating from 1/8 "at each end of the wire, holds it in place with clay, and uses tweezers to place the stripped wire portion at the top of the solder joint, the spring tension in the wire creates a certain amount of pressure.
In this way, you just need to gently touch the solder joints to melt the existing solder joints, which will pull the wires into and connect to the solder joints.
Using this method, I have achieved 100% success.
Use your multi-tool to test the continuity of the circuit between the ends of the wire, zero resistance means you have a good connection!
When I started walking along this road, it was really much easier than I thought.
Being patient in the setting and alignment of the wires is equal to being easy to weld and improving the chances of success!
These pictures show the progress from aligning the assembly and using clay putty to hold them in place, welding the assembly, using clay to hold the wire in place while welding the wire, and the final result.
USB charging Carrey wanted to charge the battery without removing my project so I used micro USB maleto-
Female connector, cut a small hole to install and wire the cable and glue it in place with Gorilla Glue.
One more question.
There are two key LEDs on the 18650 charging control board showing "charging in progress" and "charging completed ".
These are small surface mount LEDs and I can't see them when Assembly boards are installed in my project!
After doing more Google search, I learned that there are very cheap plastic fiber
The kind used for craft display-
These are relatively easy.
Each thread is about 1 m long, I cut it into 6 equal lengths, stick them together every once in a while, apply 1/4-
Make it dry with epoxy inch segments.
I then cut in the middle of each Epoxy segment to produce three or four segments of 6 fibers, glued together at both ends.
I dropped a small drop of epoxy on each LED light and used the "helper "(shown in pics)
Hold the fiber bundle on each LED until the epoxy group.
Then I drilled a small hole in my project, wired the fiber and stuck the other end in the proper position so I could see the light from the LED outside the project.
The final contact of the connector is to connect the connector to the pad in order to power the project, connect the connector to the wire using the JST curl connector-
Make sure you always use the female connector on the battery and the male connector in your project.
Curl the end of the wire
You will notice from the photo that I use small pieces of heat
Shrink the wires to fix them on the connector, just to make sure there is no extra precaution for the lithium ion fire caused by accidentally short-circuiting the pulled out power cord.
Soon, I will post another Post showing how I can use this concept for the custom Minecraft torch I created for my kids.
However, I plan to use this method in many of my future Arduino projects.
The battery is easy to use, the form factor allows a lot of flexibility, and the features provided by the soft lock switch solve a basic disadvantage of Arduino.
I hope that the path I share about my learning of these skills will help others, and the way to help me is for others to post their lessons here and on other websites.
I am also well aware that I still have a lot to learn, and I hope that some of the people who read this will comment, coming up with more ideas, components, this will also help me to take my skills to a new level.
Please let me know what you think! Happy making!