Protect your MicroPython sourcecode

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I am/was working on a large project. The project consisted of a microcontroller with some sensors. That microcontroller sends it's data to a dedicated app on an Android phone. Both the microcontroller and the app have to do some complicated calculations.
As I want to show the prototype to several people who might be commercially interested I don't want them to have the opportunity to peek at my software.

I am a lazy developer. So to speed up things I wrote the software for the microcontroller in MicroPython. It works flawless but is not hidden for anyone who connects a computer to the microcontroller. So I had to find a way to hide the program. At least to make it unreadable.

Sidenote.
When you write the programs for your microcontroller with the Arduino IDE it is almost impossible for someone to get the code out of the controller to examine it. Next to that the C++ code you wrote is compiled into machine language by the IDE which is unreadable for most. These two properties keeps your code quite safe. So maybe (when there is time) I will rewrite the program in Arduino language.

How MicroPython works.

MicroPython is an interpreted language. So you write your program in MicroPython and send it to the microcontroller. The code is stored on the microcontroller before it runs. The microcontroller has the  MicroPython interpreter on board that converts the code into something the microcontroller understands. So your sourcecode is stored on the Microcontroller ready for anyone to retrieve.

An interpreted language like MicroPython is, is therefore significant slower as the machine language the Arduino IDE produces.
The MicroPython developers found a solution to speed things up.
The MicroPython program is first converted into bytecode. The step between bytecode and machinelanguage is easier and therefore your program will run faster. Still not as fast as pure machinecode, but a lot faster as full MicroPython.

The solution

Bytecode is unreadable by us mere humans. And that offers opportunities for obfuscating the source code.

Here is a simple MicroPython program:



I just wrote this in Thonny and saved it to my computers harddisk.



And this is how the bytecode looks.
I am sure that most people that would get this code in their hands would not have a clue on how to alter this or examine it.

So what we need is a program that takes our MicroPython source code and compiles it into bytecode. And lucky for us this software exists.

Download mpy-cross

The program we need is called mpy-cross and you can get it here:
https://gitlab.com/alelec/mpy_cross/-/packages/7514584

As you can see I used this first when I still was running Windows. You might know that I switched to Linux as my operating system. There is a version of mpy-cross for Linux to and I will discuss how to use that in a future article.

At the time of this writing version V1.20.0 was the latest version. Always check for the latest version and use that.



Click on the latest version and a new window opens.



Scroll down on that page till you find the version for your computer. Mine is:
mpy-cross-v1.20.0-win_x86_64.exe

Download it and install it on your computer in a dedicate directory.
Your computer might give a warning that the software might be unsafe. I tested the package with my virus scanner before installing it and it was totally safe.

My version downloaded and had the name: mpy-cross-v1.20.0-win_x86_64
I altered the name in just mpy-cross

Using mpy-cross

Start with copying your MicroPython program into the directory where the mpy-cross program is.



The program mpy-cross needs to be started from the command line. Just double clicking it will not work.
To achieve this here is a nice trick.



Click on the yellow icon in front of the path to the directory where the mpy-cross program and your python code is.



Now type cmd



And the commandline window opens with the prompt at the right directory.

In my directory there were only two files: mpy-cross and test01.py
And the test01.py file is the file I wanted to compile.

Use the command

mpy-cross test01.py

Just replace the name test01.py with the name your MicroPython source code has.



Press enter and after a (short) while the prompt returns. The time it takes to compile your code depends on the complexity and size of your sourcecode.



And there is the bytecode file. It has the name test01 and looks like a text file but as you have seen in the second picture in this article it is nothing like a text file.

How to use the bytecode file



The file test01.mpy is uploaded to Thonny. Clicking on the name of the file produces an error. MicroPython does not seem to recognise the program code.

This is what you need to do:



Make a program containing just a single line:

import test01

That's all. It will load the file test01 and run it. You can see the result in Thonny's shell.

It does not need to be a program with a single line. The test01.mpy code can be part of a larger program. You just treat it like it is a library.

Concluding

This will not stop people from copying the bootcode file from your MicroPython device. But it will prevent most to analyse your program.

Please be aware that a bytcode file can not be used as main.py to automatically run your program at start-up. So make a one-line file (as discussed above) as your main.py file that calls the bytecode file.

Till next time
have fun

Luc Volders

Ubuntu problem with ESP8266 and Thonny solved

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As you might know I have migrated from Windows to Linux. My computer is getting old and slow. Slow is mostly due to running Windows as Windows constantly does all kinds of tasks in the background. Linux does not have that problem and is therefore a lot faster.

There are many flavors of Linux and I am running Kubuntu 24.04. LTS stands for Long Time Service meaning it is supported until june 2027.

So far so good. All the standard programs work as expected. But then I ran into a problem.

MicroPython on Kubuntu

I am using Thonny as my standard editor for MicroPython programs and that works as a charm. I connected the Raspberry Pi Pico, Pico W and ESP32 without a problem.

Only the ESP8266 (Wemos D1 Mini) would not work. Although it worked previously on my Windows setup.
It was not recognised in Thonny.



The above screendump shows that I chose the ESP8266 in the tools menu.



Nevertheless I got this error. And also several other errors.
So I started an internet search.

I found that Kubuntu installs standard a utility that is called BRLTTY This is a service that provides access to the console for a blind person using a refreshable braille display.

Fortunately I am not blind and I do not need this service. So I could delete it without consequences.

sudo apt purge brltty -y

This the command to remove brltty from Ubuntu permanently. Copy it and paste it in your Terminal program. Use sudo as you need Super User privileges to remove and install software. Linux will ask you for the administrator password.

sudo usermod -a -G dialout $USER

Then use this command to get full access to the USB port

And here is the result:



The ESP8266 comes up in the list with available Python versions.



Problem solved !

Till next time
Have fun.

Luc Volders

Overclocking the Raspberry Pi Pico in MicroPython

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This story is about overclocking (and underclocking) the Raspberry Pi Pico with MicroPython.

Sometimes you just want your program to run faster. Well you can gain speed by using C++ (Arduino language) in stead of MicroPython. But not everybody wants that as MicroPython is far easier to learn and use.

MicroPython runs on the ESP8266, ESP32 and of course on the Raspberry Pi Pico. And if you use the Picom or Pico W,  you are in luck: the Pico can be overclocked !!! And without altering anything or adding extra hardware !! The internal clock can be software wise altered !!

Overclocking

Overclocking means that you can alter the speed on which your microcontroller (or computer) works.

The documentation of the Raspberry Pi pico says that it runs normally on 133Mhz but the speed can be increased to 400Mhz.

There are two things to consider:
- The onboard SPI flash memory may give trouble when working above 260Mhz
- Overclocking might shorten the lifespan of the Pico

For most projects the Pico just runs fine. But there might be some time critical programs in which you could need a bit more speed. The lifespan shortening sounds troublesome, but until now I have not heard or read on the internet anyone who had a Pico giving up due to overclocking. Just be warned.

Overclocking in MicroPython

Overclocking is standard facilitated in MicroPython. You do not need to download extra libraries. You just need the machine library which is standard included in MicroPython.

So let's first start by examining the standard frequency. We just need two commands for that which you can put in Thonny's shell.

import machine
machine.freq()



And there it is. Standard sets MicroPython the clock-frequency to 125.000.000 which is 125Mhz. That is a bit lower as the 133Mhz the Raspberry documentation states.

Test program

Let's buid a small test program so we can see if overclocking has any effect at all.

import time

start = time.ticks_ms()
print("Micropython tips")
for x in range(1000000):
   x=x
end = time.ticks_ms()
print(end - start)

The program does nothing special. It puts the start time into a variable, then puts 1 million times the value of variable x into itself and then stores the end time. Lastly startime is subtracted from endtime and then we know how long it took.



And here is the result. our small program took about 8 and a half second to finish.

Now let us increase the clockspeed.



The command to alter the clock frequency is machine.freq(x) in which x is the frequency you need. I set the speed at 260000000 which is 260Mhz. Then I ran the program again.



And what an increase in speed !!! The program now just took 4 seconds.



The highest speed I could get was 285000000 Hz which is 285Mhz. Any higher speeds would block the communication between Thonny and the Pico. Like stated before, increasing the speed might affect your interfaces with I2C, SPI and UART. And here it shows that above 285 Mhz it definitely affects the UART communication.



At 285Mhz the program just needed a bit less than 4 seconds.

You could test if anything beyond 285Mhz might work as no Pico's is created 100% equal and you might get lucky.

I recommend not to go over 260Mhz.

Lowering the speed.

Next to increasing the speed you can also decrease the speed. Lowering the speed at which a program runs might prove usefull in debugging.



The lowest I could go was 20000000 Hz which is 20Mhz. Any lower and I lost contact with Thonny.



At 20Mhz the program took almost 53 seconds to finish.

Please test thorough !!!

Increasing the speed to the max or decreasing the speed to the minimum might influence communications with sensors and actuators working with I2C or SPI. It also may influece communication over the UART ports.

So if you need to permanently increase the speed for one of your projects please test thorough before putting it in a real life situation.

Till next time
Have fun


Luc Volders

Raspberry Pi pico with Bluetooth

For an index to all my stories click this text.

Some time ago I published a story on how to have the ESP32 communicate over bluetooth with your android Phone. Normally we use Wifi to communicate with the ESP32 but there might be circumstances in which you do not want that or can not use Wifi. You can re-read that story here: https://lucstechblog.blogspot.com/2024/08/esp32-bluetooth-classic-part-2.html

As you might know I wrote a book on the Raspberry Pi Pico which is a great microcontroller made by the Raspberry Pi Foundation. The Pico is not a linux computer but a Microcontroller like the Arduino's or ESP series. It has excellent features and a really good price-tag. A Pico can be had locally for around 5USD.  One of the readers of my book who is also a follower of this blog asked if it was possible for the Raspberry Pi Pico to communicate with his phone.
Well that is not directly possible as the Raspberry Pi Pico has no communication means on board. There is standard no Wifi or Bluetooth like the ESP8266 or ESP32 have.
There is however a solution available.

Back in 2016 as faithfull readers of this blog might remember I wrote a story on how to attach an ultrasonic distance meter to an Attiny85 and send it's data to a phone using a HC-06 bluetooth module. These modules are cheap and easy to get.

We can use that same module and attach it to a Raspberry Pi Pico to send data to your phone or receive data and commands from your phone. And that is exactly what we are going to do. You can use a HC-05 or HC-06 for this. Just use that what is most easily available.

The story written in 2016 about the Attiny 85 used C++ (Arduino language). For the Raspberry Pi Pico I am going to write a program in MicroPython.
The Phone App is written in MIT's App Inventor. You can find App Inventor here: https://appinventor.mit.edu/  

App Inventor has been featured in several stories and tutorials on this weblog which you can find here: http://lucstechblog.blogspot.com/p/index-of-my-stories.html

Bluetooth communication.

The Pico has so called UART connections. An UART is a, in this case build-in, hardware module that converts the data into a serial stream. The Pico has two UART's build in UART0 and UART1. I am using UART0 in this case.

To have the Pico communicate over bluetooth we need to attach a Bluetooth adapter that can convert the electrical signals from the Pico into a wireless transmission. The module often used for that is the HC-05 or the HC-06. So the HC-06 is connected to the internal UART. The breadboard setup shows how it is done.

The hardware setup



The Raspberry Pi Pico has ample I/O pins so for this test I am using 2 I/O pins for the communication with the HC-06 bluetooth module, and I use 4 I/O pins to attach leds.


The HC-06 is attached to the GND (pin 38) and 3V3-OUT (pin 36) for getting it's power. The TX line of the HC-06 is attached to the RX line (pin 2) of the Pico. The RX line of the HC-06 is attached to the TX line (pin 1) of the Raspberry Pi Pico. So the RX and TX lines are crossed. This makes sense. The Pico sends (TX) data to the Bluetooth module that receives that data (RX) and the other way round.

Next the 4 leds are connected to GND using a current delimiting resistor of 220Ohm and connected to the Pico's pins 15, 16, 17 and 19 which are GPIO 14, 13, 12 and 11.

Last year I made a Raspberry Pi Pico pin layout which you can print and lay on top of the Raspberry Pi Pico for easy reference. You can find that here: http://lucstechblog.blogspot.com/2021/03/raspberry-pico-pin-layout-help.html

The App

To have your Pico and Phone talk to eachother you need an App on your phone. The App I am going to show how to develop is for an Android Phone. As App Inventor nowadays also can be used to develop Apple app's you could adapt the program for an Iphone. However you're on your own here as I do not own an IPhone and am not willing to buy one due to it being terribly overpriced.

Unfortunately I do not have the space and time here to give you a complete App Inventor course. App Inventor does not have a steep learning curve and spending some hours with the program should get you going. Next to that there are several tutorials and examples on this weblog and App Inventor itself offers several tutorials. Check those here http://lucstechblog.blogspot.com/p/index-of-my-stories.html and here: https://appinventor.mit.edu/



This is how the screen will look eventually. At the top there is a ListPicker used for picking the right Bluetooth device. Below that there is a Tablearrangement. Inside the TableArrangement I placed 8 buttons that send commands for setting the led on or off.
Below that you see an empty square. That is a label (Label2) in which texts received from the Raspberry Pi pico will be shown.
And below that Label is Label1 with a ridiculous copyright notice.

Arrange the items to your own linking and give them the looks and colors of your choice. Play with this to learn how to use App Inventor and it's possibilities and functions.

There are 3 non-visible components at the bottom of the designer screen. The first one is the BluetoothClient component, the second is the Notifier component and the last is the clock component. You can find these in the menu on the left side of the designer screen (not shown here).
Drag them into the phone simulation screen and they will be placed at the bottom like shown here.

Now switch over to the blocks section.


This is a picture of all the necesary blocks. It may look complicated but if you get the hang of it, it really isn't.


Start with a Listpicker and put all the names and Bluetooth adresses in the list.

When the ListPicker has all the Bluetooth data and the user presses (clicks) on the desired Bluetooth device connect to it. When connected set a message on the screen (with the notifier) that the connection has succeeded or failed.


Create a block for each button that sends a particular text over Bluetooth when the button is clicked.


Here you can see the blocks that are used to set the first led on or off. When Button1 is clicked first the Bluetooth connection is tested. No use to try to send a command over Bluetooth when the device is not connected...
Then we send on1# if Button1 is pressed or off1# when Button2 is pressed.
The # is attached to the text as a means for the Pico's Python program to detect if receiving the message is completed.

The blocks for Button3 to Button8 are identical and only differ in the message they are going to send.

This last block uses the clock function to check every second wether there is a message received over Bluetooth. If a message is received it is displayed in Label2.

And that completes the App for your phone.

If you do not want to compose all the blocks yourself I have a copy of the above code available for you to download here:

https://www.mediafire.com/file/554kyre473onlh0/Pico_bluet_SR.aia/file

The Python program for the Pico.

Now we have a complete app available that can send and receive data over Bluetooth let's look at the Pico side. Here is the complete MicroPython program.

import os
import utime
from machine import UART, Pin

#print sys info
print(os.uname())

L1 = Pin(14,Pin.OUT)
L2 = Pin(13,Pin.OUT)
L3 = Pin(12,Pin.OUT)
L4 = Pin(11,Pin.OUT)

#indicate program started visually
led_onboard = machine.Pin(25, machine.Pin.OUT)
led_onboard.value(1)     # onboard LED ON for 0.5 sec
utime.sleep(0.5)
led_onboard.value(0)     # onboard LED ON for 0.5 sec

uart = machine.UART(0, baudrate=9600,
                    bits=8, parity=None, stop=1)
print(uart)

uart.write("hello")
utime.sleep(1)
uart.write("The temperature is : ")
uart.write(str(35))

L1.value(1)
utime.sleep(1)
L1.value(0)

L2.value(1)
utime.sleep(1)
L2.value(0)

L3.value(1)
utime.sleep(1)
L3.value(0)

L4.value(1)
utime.sleep(1)
L4.value(0)

while True:
        b=""
        a=""
        c=""
        while a != "#" :
           a = uart.read(1)
           c = (a.decode('utf-8'))
           a = c
           if (c != "#"):
             b = b + c
             print("received chars: ",len(b)," = ",b)
            
        if "on1" in b:
            L1.value(1)
            uart.write("Led 1 On")
        if "off1" in b:
            L1.value(0)
            uart.write("Led 1 Off")
            
        if "on2" in b:
            L2.value(1)
            uart.write("Led 2 On")
        if "off2" in b:
            L2.value(0)
            uart.write("Led 2 Off")

        if "on3" in b:
            L3.value(1)
            uart.write("Led 3 On")
        if "off3" in b:
            L3.value(0)
            uart.write("Led 3 Off")
            
        if "on4" in b:
            L4.value(1)
            uart.write("Led 4 On")
        if "off4" in b:
            L4.value(0)
            uart.write("Led 4 Off")

As usual I will show how this program works by highlighting certain parts.

import os
import utime
from machine import UART, Pin

First we import all the necesary libraries.

L1 = Pin(14,Pin.OUT)
L2 = Pin(13,Pin.OUT)
L3 = Pin(12,Pin.OUT)
L4 = Pin(11,Pin.OUT)

The four led's are defined and the I/O pins where they are attached to are set as OUTput.

#indicate program started visually
led_onboard = machine.Pin(25, machine.Pin.OUT)
led_onboard.value(1)     # onboard LED ON for 0.5 sec
utime.sleep(0.5)
led_onboard.value(0)     # onboard LED ON for 0.5 sec

Then we blink the Pico's internal led as an indication that the program has started.

uart = machine.UART(0, baudrate=9600,
                    bits=8, parity=None, stop=1)
print(uart)

These lines define the serial communication's settings and display them in Thonny's shell when the program runs.

uart.write("hello")
utime.sleep(1)
uart.write("The temperature is : ")
uart.write(str(35))

This is a test in which we send a fake message to the phone. First the word "hello"is send and next "The temperature is 35" As you can see the last line converts the number 35 into a string that can be send over Bluetooth.

L1.value(1)
utime.sleep(1)
L1.value(0)

L2.value(1)
utime.sleep(1)
L2.value(0)

L3.value(1)
utime.sleep(1)
L3.value(0)

L4.value(1)
utime.sleep(1)
L4.value(0)

The leds are all set on and then off as a test so we can see they are working and attached to the right I/O pins.

Then comes the most important part of the program. It is where an incoming message from the Phone is read and decoded.

while True:
        b=""
        a=""
        c=""
        while a != "#" :
           a = uart.read(1)
           c = (a.decode('utf-8'))

The program starts with defining some helper variables and making them empty.
Next a test is done wether the variable a comntains "#" if that is the case it is the last character received and it should be ignored.

If it is not "#" the next character is read from the uart and decoded to a normal ascii value.

           a = c
           if (c != "#"):
             b = b + c
             print("received chars: ",len(b)," = ",b)

Again we test wether the received character is "#" and if not the character is added to the variable b. Then we print in the shell the received characters and the length of the total received characters. This is just a test to see if everything send from the phone is indeed received.

        if "on1" in b:
            L1.value(1)
            uart.write("Led 1 On")
        if "off1" in b:
            L1.value(0)
            uart.write("Led 1 Off")

When "#" is received the command is now complete and stored in the variable b. Now we can test which command is received and set the appropriate led on or off.
Then we send "Led 1 On" or "Led 1 Off" back to the phone so the phone can check if the command really has been received and the command is executed.
These lines are repeated for all 4 leds.

In the field

When te App is started firrst press on the field with the text "Pick your Bluetooth device" and make sure Bluetooth is activated on your phone.

A new screen opens showing all Bluetooth devices available and the ones that you have used in the past. The top one has the Bluetooth adress and name (HC-06) we want to connect to. Press on that line and the connection is made.

Now you can use the app and switch the led's on and off.

This clearly demonstrates how to receive data from Bluetooth and how to send data over Bluetooth.

Of course this is just a framework to send and receive all kinds of data from your phone to the Raspberry Pico and the other way round.

For more detailed info on the Raspberry Pi Pico, a short course on MicroPython and using all kinds of sensors with the Pico please buy my book Raspberry Pi Pico Simplified: https://lucstechblog.blogspot.com/2021/08/raspberry-pi-pico-simplified-now.html

Till next time
have fun

Luc Volders

Raspberry Pi Pico reset and bootselector

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Anybody who has worked with the Raspberry Pi Pico knows that sometimes you will have to upload a new version of MicroPython.



The common way to install a new version of the language is to press the bootselector switch and then insert the USB connector.

There is however another and more elegant version.

For testing purposes I always connect a reset button to my Pico. That is easy to do. Just connect a pushbutton to pin 30 (reset) and GND. No need for full up resistors.

The sequence is to press the bootselector switch and hold it. Then briefly press the rest button. The Pico will then immediately switch to flash mode and will be available as a flash disc on your computer.

And just sometimes the bootselector breaks. If that happens just connect a button to J6 which is located at the bottom of the print like this story shows:
https://lucstechblog.blogspot.com/2025/04/repair-defective-bootselector-switch-on.html

Till next time
Have fun


Luc Volders

Repair a defective bootselector switch on a Raspberry Pi Pico

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I wanted to install the latest version of MicroPython on a Raspberry Pi Pico W when disaster struck. The bootselector switch broke.



This is how the bootselector normally looks



This is how mine looked.

The bootselector switch is the switch you have to press, and connect USB at the same time, to get the Pico in a state where you can upload new firmware. No bootselector: no new firmware !!! So this is a rather important switch.

So I wanted a solution and started looking at the Raspberry Pi forum. It seems that a couple of guys had the same problem. But they offered no solution.

Then I turned to the Pico's datasheet. Everyone seems to see manuals and datasheets as a last resort, but it should be the first......... Here is a link to the datasheet: https://datasheets.raspberrypi.com/picow/pico-w-datasheet.pdf

 

At the bottom side of the Pico there are several contacts. TP4 TP5 and TP6.



And the datasheet shows that TP6 is the contact to the bootselector switch.



And this is how it looks in the real world. So the solution is easy. Solder a wire to TP6.



The TP6 pad is large enough to solder with a normal soldering iron with a small tip.

And yes: I am a sloppy solderer and the wire is too long.

The easy way is to start with putting some solder on TP6. Then put some solder on your wire. Then solder the wire to TP6.

When all your projects are breadboard based sacrifice a dupond wire for this. I used a simple flexible wire so I can use that on a breadboard but also solder it to a pushbutton when needed.

To get the Pico in bootselector mode just connect the wire to GND and plug in your USB cable. Then disconnect the wire and you can upload the new firmware.

Till next time
have fun


Luc Volders

Linux webserial and webusb problem

For an index to all my stories click this text.

Lately I have been looking into web-based programs that allow to program a Raspberry Pi Pico or ESP32. There are two block-programming based programs called Ioty and Bipes. They work a bit like MIT's App Inventor.

Another thing I have been looking at is Viper Ide. This is an editor for MicroPython programs. I normally use Thonny for creating programs in MicroPython. Thonny is a program that you download onto your computer and then run it. Just like all regular programs.

Viper IDE runs in your browser. You do not need to download anything. Just point your browser to https://viper-ide.org/ and start programming.

This all sounds fine, however I ran into a problem with these web-programs.

Webserial and Webusb

At one time or another you need to connect your microcontroller to your computer with a USB connection. This is to transfer the program from your computer to the microcontroller. And to use USB from your browser, the browser must be able to use Webserial or Webusb. So you can not use Firefox. Chrome does the job.

I am not running a Windows computer (anymore), my system runs Linux. So there is no Chrome browser but there is a derivative called Chromium.

And there I was stuck. Viper IDE told me that it wanted to connect but no compatible devices were found.
As Thonny operated flawless I knew there was nothing wrong with my USB ports. So there must be something wrong with the communication between the webbrowser and the microcontroller.

Safety first

Linux is an operating system that focuses on safety and user rights. Users can not access files, folders and ports without first getting the rights to access them from the administrator (root). And then root can grant access to only read or read and write. This may seem like an annoyance but it makes sure that nobody can get to your data, or delete it, without explicit permission.

And that is what here is the case. We have to grant the webbrowser access to the USB ports. That can be done as follows:

sudo snap connect chromium: raw-usb

This is the command for Kubuntu. Kubuntu is based on Debian so, I presume, this will work on  most Debian derivative distributions.

It works

And now it works.

Chromium lists all USB ports and the Raspberry Pico was the first listed,

Play it safe

Although Linux is a really safe operating system it is always better to be safe then sorry. A lot of hackers are around who want to do nasty things on your machine. So what I do is to disconnect the USB port from the web-browser when I am done programming. The command for that is:

sudo snap connect chromium: raw-usb

That's all for now
Till next time


Luc Volders

Print your own USB connector

For an index to all my stories click this text.

Sometimes I find something on the web that is so usefull that I want to share it with you.

Powering your circuits.

When testing and building a small circuit with just one or two sensors you can use the power that your microcontroller supplies over it's 5V pin. Both the ESP32 and the Raspberry Pi Pico have a 5V and 3V3 power out pin.

But when I need more power I use an USB breadboard connector to power the project.

An example is this circuit where two TM1637 7 segment displays are connected to a Raspberry Pi Pico. The Raspberry pi pico is powered through it's USB port and on the left-top side you can see a breadboard USB connector attached to a USB power plug.

Nothing wrong with this but I always seem to run out of breadboard USB connectors.

3D printer to the rescue

Then I found this on the web:
https://www.instructables.com/Minimalist-USB-Connector-No-Special-Hardware-Requi/

This is a 3D printed USB connector. The photo shows the assembled version.
But does it work ????

Works like a charm !!!
As you can see the USB connector is plugged into a powerbank and the multimeter shows that a nice 5V is supplied.

The STL files

The connector consists of 2 parts.

You can find the STL files in the original story which you can find here:
https://www.instructables.com/Minimalist-USB-Connector-No-Special-Hardware-Requi/

The first part is the bottom in which you need to insert the wires. The second part is the top which you should glue and press on to the bottom part when the wires are placed. The top part has ridges that help keep the wires in place.

This is how the files look in my slicer. I use Cura.

Set the quality at 0.2mm and supports on. As these are small parts you could set adhesion also on.

Assembling

I used solid copper wire with a diameter of 0.5mm. That worked very well.

I took a slightly different approach to assembling as what the original developer described.

First I stripped the wires.

Then I pulled the stripped part through the holes.

Then I glued the lid on.
The last step was to cut off the excess wire.

The blue wire at the top is GND.
The red wire at the bottom is VCC (5V).
Please test before you actually put it to use to make sure the wires are not twisted. If you mix the wires up you might/will blow up your circuit so test, test, test !!!

The wires are thick enough to fit direct into a breadboard.

You can make the wires any length you want. Short to connect to a powerbank and fit on your desk. Or make them long to connect to a wall outlet with an USB power plug.

I have printed several of these. They are ready to use in my drawer. A really great design.

Til next time
Have fun

Luc Volders