Week04 | Embedded Programming

1. Objectives

• Study and analyze the RP2040 microcontroller datasheet to understand architecture, GPIO configuration, memory structure, and peripheral interfaces.
• Explore and compare different programming environments including MicroPython, CircuitPython, Thonny, and Arduino IDE.
• Perform practical soldering of components to prepare and verify the microcontroller board functionality.
• Develop and upload test programs using Arduino and MicroPython to validate input/output operations.

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Thonny IDE Setup and MicroPython Configuration (RP2040)

For this assignment, I explored different development environments including MicroPython, CircuitPython, Arduino IDE, and mBlock. After testing, I decided to primarily use Thonny IDE for MicroPython development with the Raspberry Pi Pico (RP2040), as it provides a clean interface and direct serial interaction with the board.

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Step 1 – Installing / Updating MicroPython Firmware

To begin, I installed MicroPython firmware on the Raspberry Pi Pico using Thonny's built-in installer.

• Open Tools → Options → Interpreter
• Select MicroPython (Raspberry Pi Pico)
• Click Install or update MicroPython
• Put Pico into BOOTSEL mode and install firmware

The firmware was successfully installed (MicroPython v1.27.0 on RP2040).

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Step 2 – Configuring Interpreter

After installation, I configured the interpreter inside Thonny:

• Select MicroPython (Raspberry Pi Pico)
• Choose the correct COM port (Board CDC)
• Enable auto-detection

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Step 3 – Accessing MicroPython Shell

Once connected, the MicroPython REPL (Shell) becomes active. This allows direct interaction with the microcontroller.

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Step 4 – Testing GPIO using machine.Pin

I explored the machine library from MicroPython documentation. Specifically, I used the Pin class to control GPIO outputs.

Basic LED test on onboard LED (GPIO 25):

from machine import Pin
import time

led = Pin(25, Pin.OUT)

while True:
    led.on()
    time.sleep(1)
    led.off()
    time.sleep(1)

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Step 5 – Saving Code to Pico (main.py)

To make the program run automatically after reset, I saved the script as main.py directly on the Raspberry Pi Pico.

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Results

• Successfully installed MicroPython on RP2040
• Configured Thonny interpreter and COM port
• Tested onboard LED blinking
• Tested external LED (Neon light)
• Saved auto-run script as main.py

At this stage, I was able to successfully implement blinking LED and neon light control. Further experimentation with input devices and advanced peripherals will be continued in the next phase.

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MicroBlocks – Programming Xiao RP2040

For this assignment, I explored MicroBlocks as a visual programming environment for the Xiao RP2040 board. MicroBlocks allows real-time interaction with the microcontroller and is useful for rapid testing of input and output devices.

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Step 1 – USB Connection

The board was connected via USB. From the top-right menu, I selected Connect → connect (USB). The device appeared as Board CDC (COM7), confirming that the serial communication was working correctly.

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Step 2 – Board Selection

After establishing the USB connection, I verified that the selected board was Xiao RP2040. This ensures correct pin mapping and compatibility with the RP2040 architecture.

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Step 3 – Adding NeoPixel Library

To control the RGB LED (NeoPixel), I opened the library manager and added the NeoPixel (WS2812) library. This provides blocks for controlling RGB color values.

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Step 4 – Writing the Program

I created a simple program using block-based logic:

• When started
• Attach 1 LED NeoPixel strip to pin 12
• Set all NeoPixels to a selected RGB color

This basic program allowed me to test output control of the NeoPixel LED.

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Result

The NeoPixel LED responded correctly to the programmed instructions. This confirms:

• Successful USB communication
• Correct board configuration
• Working output device (NeoPixel)

Status: Completed ✅

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Week 04 – Programming XIAO RP2040 (Arduino)

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1. Installing Board Support

After installing Arduino IDE (v2.3.7), I added the RP2040 board support package using the Additional Boards Manager URL.

File → Preferences → Additional Board Manager URLs

https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json

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2. Selecting Board and COM Port

After installing the board package, I selected:

• Board: Seeed XIAO RP2040
• Port: COM9

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3. Installing Required Core

Arduino prompted installation of the Raspberry Pi Pico / RP2040 core. The installation was completed successfully.

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4. Blink Program (RGB LED Test)

I wrote a simple program to blink the green LED of the RGB LED.

#define PIN_RED 17
#define PIN_GREEN 16
#define PIN_BLUE 25

void setup() {
  pinMode(PIN_RED, OUTPUT);
  pinMode(PIN_GREEN, OUTPUT);
  pinMode(PIN_BLUE, OUTPUT);

  digitalWrite(PIN_RED, HIGH);
  digitalWrite(PIN_GREEN, HIGH);
  digitalWrite(PIN_BLUE, HIGH);
}

void loop() {
  digitalWrite(PIN_GREEN, LOW);
  delay(500);
  digitalWrite(PIN_GREEN, HIGH);
  delay(500);
}

Result: Green LED blinking successfully.

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5. OLED Display Test (SSD1306)

I tested an SSD1306 OLED display using Adafruit libraries and I2C communication.

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define SCREEN_ADDRESS 0x3C

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

void setup() {
  Serial.begin(115200);
  delay(50);

  display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS);
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
}

void loop() {
  display.clearDisplay();
  display.setCursor(28, 25);
  display.print("Hello world!");
  display.display();
}

Result: OLED successfully displayed "Hello world! (need attention)"

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6. Compilation and Upload

The sketch compiled successfully. Memory usage and flashing process were verified during upload.

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Learning Outcome

• Installed RP2040 board support in Arduino IDE
• Configured Board and COM Port correctly
• Programmed GPIO pins
• Controlled RGB LED
• Interfaced OLED display using I2C
• Understood compilation and upload workflow

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