4. Embedded Programming
This week is my introduction to microcontrollers and creating codes to operate them. So far the most I have done regarding coding is doing very basic commands in Scratch. Even then, the outcomes weren’t great. For this week’s assignment, I will be learning about the Seeed Xiao RP2040 and the Xiao ESP32-C3 which are the micro controllers I intend to use in my final project. I hope to use the knowledge from this week to inform how best to integrate my coding and hardware for the coming weeks.
Seeed Xiao RP2040 Datasheets and Specifications
Seeed Xiao ESP32-C3 Datasheets and Specifications
Hardware Testing
The goal for this assignment was to make a blinking LED. To start the assignment I turned to my friend ChatGPT as I had no idea how to begin otherwise. My prompt was: please write a micropython code to make a LED blink using an RP2040 microcontroller on a breadboard.
Which resulted in the following response:
Link to ChatGPTHere’s a simple MicroPython example to blink an LED using an RP2040 (such as a Raspberry Pi Pico) on a breadboard.
Hardware setup
-RP2040 board (e.g. Raspberry Pi Pico)
-LED
-220–330 Ω resistor
-Breadboard + jumper wires
Wiring:
-GPIO 15 → Resistor → LED anode (long leg)
-LED cathode (short leg) → GND
(You can change the GPIO pin in the code if needed.)
MicroPython LED Blink Code
from machine import Pin
import time
# Set up the LED pin (change 15 if using a different GPIO)
led = Pin(15, Pin.OUT)
while True:
led.value(1) # Turn LED ON
time.sleep(0.5) # Wait 0.5 seconds
led.value(0) # Turn LED OFF
time.sleep(0.5) # Wait 0.5 seconds
How it works (quick explanation)
-Pin(15, Pin.OUT) sets GPIO 15 as an output pin
-led.value(1) supplies 3.3V → LED turns on
-led.value(0) cuts power → LED turns off
-time.sleep() controls the blink speed
Tips
-To blink faster or slower, adjust the sleep() values
-If your LED doesn’t light up, flip it around (polarity matters)
You can use the onboard LED instead by replacing the pin line with:
led = Pin("LED", Pin.OUT)
If you want, I can also:
-Add PWM fading
-Blink multiple LEDs
-Rewrite this for Thonny upload workflow
-Or adapt it for a custom RP2040 board
It took me way too long to make sense of everything ChatGPT was telling me so I decided to assemble the list of components it gave me.
Thankfully my lab had some used microcontrollers, pinned LEDs, breadboards, jumper wires, resistors and a multimeter. I also picked up a 3V cell battery and a few strips of copper tape to add to my experimenting.
ChatGPT said that I would need a 220-330 Ω resistor. I was able to decode the marking on the container of resistors I found in the lab and tested them with the multimeter to ensure I was using the right ones. I noted from my test that these seemed to be approximate values as the actual values I got were 219.1Ω and 326.9Ω
In my day job as a STEAM FabLab Educator, I teach kids about simple circuits both in parallel and series configurations. I was trying to see if that experience could help me build a basic understanding of how the breadboard works and the flow of electricity from positive to negative. My first test worked very well. I got the LED to light up and everything made sense. In the image you can also see how I connected the jumper wires to the battery using the conductive tape.
The big difference came when I tried using the resistors. The LED wouldn't turn on with the resistor and my best guess was that the power source was not strong enough to need a resistor and that the reduced power was too week to light the LED. Through other tests, I learned that LEDs of different colors have different power requirements. Red, green and yellow lights were easier to power, while white and blue needed more electricity.
Next I tried connecting the microcontrollers to my computer. I mentioned before that they were used and I didn’t know what they were programmed to do or if they even worked. To my surprise, they lit up and I could actually play with them. That said, I still didn’t know how to play with them.
Failing to Understand Programming
To dive deeper into the world of these microcontrollers, I needed to look at all of my available information simultaneously. The videos got me onto Thonny for the Micropython, I tried to understand the pinouts for the RP2040 and I crossreferenced the ChatGPT for more guidance… It didn’t work. I just got extremely overwhelmed and confused by the whole process.
Understanding the Concepts with Microbits
I did a hard pivot to the only form of coding I knew. Scratch was also a bad idea because I couldn’t get my Microbit to connect. This is a good time to mention that I was given a free microbit a few weeks before at the hack night event that happened in the lab.
Pivoting again, I decided to look into microbits and see if I could connect to a dedicated site for the controllers. I was so excited to find that Microsoft hosts a microbit site that was actually very easy to use https://makecode.microbit.org.
I started the code by using the ‘On button A pressed’ and ‘On button B pressed’ input components. Then, I added the ‘Show LED’ component to each input. For the ‘A’ input, I created an ‘A’ shape in the square grid. I did the same in the ‘B’ input swapping the ‘A’ shape for ‘B’.
Link to Microbit Code
When I finished my first 2 commands, I created a new input ‘On button A+B pressed’ with the prompt ‘Show string “Hello!”’I was then able to download my code to the microbit and test the output.