For an index to all my stories click this text

This story is about the rigid led filament. There is also a flexible version which will be discussed in an upcoming story.

I saw on the internet something that looks like a small led strip. They have several names: Led Filament, Cob Led Filament and Edison bulb led parts.

# -------------------------------------------
# simple test for setting filament on and off
# -------------------------------------------
from machine import Pin
import time
filament = Pin(16, Pin.OUT)
while True:
 filament.value(1)
 time.sleep(1)
 filament.value(0)
 time.sleep(1)

# -------------------------------------
# test program for dimming led filament
# with PWM
# -------------------------------------
import machine
import time
filament = machine.PWM(machine.Pin(16))
filament.freq(1000)
while True:
 min = 0
 max = 65536
 for i in range(min,max):
 filament.duty_u16(i)
 time.sleep(.00015)
 time.sleep(1)
 for i in range(max,min,-1):
 filament.duty_u16(i)
 time.sleep(.00015)
 time.sleep(1)

For an index to all my stories click this text

After my story about Dweet.cc and Freeboard I got some mails from readers of that wanted to know how to send data to Dweet.cc and retrieve data from Dweet.cc with MicroPython.

Well here we go.

Sending a dweet to Dweet.cc

The API call I used to send a temperature value to Dweet.cc with the thingname lucstechblog is as follows:

https://dweet.cc/dweet/for/lucstechblog?temperature=25

To use that API call in a MicroPython program you can use the following code:

import network
import urequests
# Router credentials
ssid = "YOUR_ROUTER_NAME"
pw = "PASSWORD"
print("Connecting to wifi...")
# wifi connection
wifi = network.WLAN(network.STA_IF) # station mode
wifi.active(True)
wifi.connect(ssid, pw)
# wait for connection
while not wifi.isconnected():
 pass
# wifi connected
print("Connected. IP: ",str(wifi.ifconfig()[0], "\n"))
# Replace 'lucstechblog' with your actual thing name
# Replace valuename with the name of the value you are sending
# Replace value with the actual value
thingname = 'lucstechblog'
valuename = 'temperature'
value = 25
value = str(value)
url = 'https://dweet.cc/dweet/for/'
url = url + thingname
url = url + "?"
url = url + valuename
url = url + "="
url = url + value
response = urequests.get(url)
print(response.text)
response.close()

thingname = 'lucstechblog'
valuename = 'temperature'
value = 25
value = str(value)

url = 'https://dweet.cc/dweet/for/'
url = url + thingname
url = url + "?"
url = url + valuename
url = url + "="
url = url + value

import network
import urequests
import ujson
# Router credentials
ssid = "YOUR_ROUTER_NAME"
pw = "PASSWORD"
print("Connecting to wifi...")
# wifi connection
wifi = network.WLAN(network.STA_IF) # station mode
wifi.active(True)
wifi.connect(ssid, pw)
# wait for connection
while not wifi.isconnected():
 pass
# wifi connected
print("Connected. IP: ",str(wifi.ifconfig()[0], "\n"))
# Replace 'my-thing-name' with your actual thing name
thing_name = 'lucstechblog'
url = 'https://dweet.cc/get/latest/dweet/for/'
url = url + thing_name
response = urequests.get(url)
print(response.text)
response.close()

url = 'https://dweet.cc/get/latest/dweet/for/'
url = url + thing_name

import time
import network
import urequests
import ujson
# Router credentials
ssid = "Ziggo2903181"
pw = "ptzbB2ohKbgs7agp"
print("Connecting to wifi...")
# wifi connection
wifi = network.WLAN(network.STA_IF) # station mode
wifi.active(True)
wifi.connect(ssid, pw)
# wait for connection
while not wifi.isconnected():
 pass
# wifi connected
print("Connected. IP: ",str(wifi.ifconfig()[0], "\n"))
# Replace 'my-thing-name' with your actual thing name
thing_name = 'lucstechblog'
#url = 'http://192.168.178.62:8000/get/latest/dweet/for/Kit-pow'
#url = 'http://dweet.me:3333/get/latest/yoink/from/Man-temp'
url = 'https://dweet.cc/get/latest/dweet/for/'
url = url + thing_name
response = urequests.get(url)
print(response.text)
print ("============================================")
# Parse the JSON string
data = ujson.loads(response.text)
# Extract the temperature value
tempvalue = data["with"][0]["content"]["temperature"]
# Display the result
print("Temperature is:", tempvalue)

data = ujson.loads(response.text)

tempvalue = data["with"][0]["content"]["temperature"]

print("Temperature is:", tempvalue)

For an index to all my stories click this text.

In a previous story I informed you (as if you did not know) that Dweet.io stopeed working. They suddenly ceased their service and left many users in the dark. Their IOT projects just stopped working. You can read that story here:
https://lucstechblog.blogspot.com/2025/08/dweet-is-dead-long-live-dweet.html

For an index to all my stories click this text.

I fall for it every time, and this time I have had enough.
Read on if you want to know what this is about.

It started a few year ago.

First there was Blynk.I was using Blynk for several projects. You could use their free service on which you could use a limited amount of IOT devices. But you could also install your own Blynk server on a Raspberry Pi and then you could use unlimited devices. And suddenly they switched to Blynk 2. The free server was removed from Github and the accompaning App was removed from Android Play.
Blynk 2 had at that time just a very limited free use. So that was the end of it.

Then there was IFTTT. They suddenly stopped allowing users to use free webhooks. You needed a payed subscription for that. So for using IFTTT with your IOT projects you suddenly needed a payed subscription. So that was the end of it.

Appybuilder, which was an app-building system based on MIT's App Inventor ceased working some time ago.

And the list goes on and on. Several services start giving their customers free access and then suddenly become paid services or quit alltogether.

And now Dweet

I have made some projects with dweet.io and published several stories about this service on this weblog. If you have no clue about what Dweet is read this story first:
https://lucstechblog.blogspot.com/2019/05/dweet-volatile-iot-cloud-service.html

And just January this year they quit too.

For an index to all my stories click this text

In the previous story I wrote how you can make your MicroPython sourcecode unreadable for most users. I did that for trying to protect my program. The way to do this is to convert your program into bytecode. You can read that story here:
https://lucstechblog.blogspot.com/2025/06/protect-your-micropython-sourcecode.html

After I published that story here on my weblog I received a mail from a reader that asked if the bytecode was actually faster as standard MicroPython. The question is valid as bytecode is actually easier to interpret as MicroPython code.

So I did some tests.

Prime numbers

I took a smal program that calculated and printed a few thousand prime numbers. Here is the code.

import time
start_time = time.ticks_ms()
def is_prime(n):
 if n < 2:
 return False
 for i in range(2, int(n ** 0.5) + 1):
 if n % i == 0:
 return False
 return True
count = 0
n = 2
while count < 5000:
 if is_prime(n):
 print(n)
 count += 1
 n += 1
end_time = time.ticks_ms()
elapsed_time = time.ticks_diff(end_time, start_time)
print("Elapsed time:", elapsed_time, "milliseconds")

import time
start_time = time.ticks_ms()
def is_prime(n):
 if n < 2:
 return False
 for i in range(2, int(n ** 0.5) + 1):
 if n % i == 0:
 return False
 return True
count = 0
n = 2
while count < 5000:
 if is_prime(n):
 count += 1
 n += 1
end_time = time.ticks_ms()
elapsed_time = time.ticks_diff(end_time, start_time)
print("Elapsed time:", elapsed_time, "milliseconds")

For an index to all my stories click this text

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

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.