Embedded programming 🚀

Assignment Objectives 📜

This week’s assignment was all about getting up close and personal with microcontrollers. The tasks included:

📖 Browsing the datasheet for a microcontroller
💻 Writing and simulating a program that:
🎛️ Interacts with local input/output devices
📡 Communicates via wired or wireless connections
⚡ Extra credit: Testing it on a development board
💾 Extra extra credit: Experimenting with different languages and development environments

My Microcontroller Journey 🛠️

I've spent years working with Arduino Uno, crafting conceptual projects like:

🎶 A device that taps into brain waves to generate music
🤖 Depth-sensing robots using IR sensors
🚗 Line-following bots powered by ultrasonic sensors

But this week, I stepped out of my comfort zone and explored new boards and environments. My mission? Write some code, simulate output, and see where things break (and hopefully get fixed).

Group Assignment: Exploring Different Boards 🔍

As part of the group assignment, we explored different microcontroller workflows. Here’s a quick overview of the boards we worked with as documented by Samruddhi:

Arduino Uno 🏗️

Processor: ATmega328P (8-bit)
Ease of Use: Beginner-friendly, massive community support
Programming Environment: Arduino IDE
Strengths: Simple, reliable, tons of libraries
Weaknesses: Limited processing power, lacks built-in Wi-Fi/Bluetooth

Xiao ESP32 C3 📡

Processor: ESP32-C3 RISC-V (32-bit)
Ease of Use: Moderate, some learning curve with ESP-IDF
Programming Environment: Arduino IDE, ESP-IDF, MicroPython
Strengths: Wi-Fi and Bluetooth built-in, small form factor
Weaknesses: Fewer I/O pins compared to full-size ESP32

RP2040 ⚡

Processor: Dual-core ARM Cortex-M0+
Ease of Use: Moderate, requires understanding of PIO (Programmable I/O)
Programming Environment: Arduino IDE, MicroPython, C/C++
Strengths: Fast, flexible, powerful GPIO handling
Weaknesses: No built-in Wi-Fi/Bluetooth, more complex setup

Comparing Development Workflows ⚙️

Feature	Arduino Uno 🏗️	Xiao ESP32 C3 📡	RP2040 ⚡
Processor	ATmega328P (8-bit)	ESP32-C3 RISC-V (32-bit)	Dual-core Cortex-M0+
Wi-Fi/Bluetooth	❌ No	✅ Yes	❌ No
GPIO Pins	14 Digital, 6 Analog	11 Digital, 4 Analog	30 GPIO
Programming Environments	Arduino IDE	Arduino IDE, ESP-IDF, MicroPython	Arduino IDE, MicroPython, C/C++
Best For	Simple projects, prototyping	IoT applications, wireless projects	High-performance embedded projects

Datasheets

I went through the datasheet of both the microcontrollers that I used in this week. You can check them out here:
SEEED XIAO RP2040
XIAO ESP32

Pinouts

ESP32 ES{32 pinout} RP2040 RP2040 pinout

RP2040: Blinky Beginnings ✨

🏁 Started with the RP2040 board

Interface of the working environment

🔎 Explored project templates to understand pin configurations

💡 Made an LED blink as a basic first project
🎮 Configured an accelerometer to change Neopixel colors based on orientation

Circuit diagram

🤦‍♂️ Debugging ensued, but no output—will revisit in Electronics Week

Code error

Failed to find library

Xiao ESP32 C3: Getting in the Groove 🌈

🎛️ Played with the default LED sequence

📝 Modified the text output

🔀 Changed the LED order to better understand the board

📜 Tested Neil’s push-button code in Wokwi (didn’t work 😐)
🔧 Added an external push button to get a text output on press

💡 Attempted to use the button to light an LED, but Wokwi had traffic overload

Traffic went down

Now that Wokwi has a little less traffic, its time to pickup where I left off. This time i will only be working with the ESP32 and using ChatGPT to help with the code, with some manual debugging ofcourse!

Basic Input

I connected a push button on Digital pin 2 of the ESP32 and connected the other end to the GND pin. I also activated the internal pullup by adding it in the code. And this is how it went:

Code

Input.cpp

#define BUTTON_PIN D2  // GPIO pin connected to button

void setup() {
  Serial.begin(115200);
  pinMode(BUTTON_PIN, INPUT_PULLUP);  // use internal pull-up resistor
}

void loop() {
  int buttonState = digitalRead(BUTTON_PIN);

  if (buttonState == LOW) {
    Serial.println("Button Pressed");
  } else {
    Serial.println("Button Released");
  }

  delay(200); // debounce delay
}

Sensors and output devices

Next I paired a Light dependend resistor (LDR) module to sense light around and mapped its readings to the colour output of a neopixel ring. I did the colour change in a sweep movement and when I simulated the code I tried the output on extreme sides of the light exposure.

Code

Sensors & Output devices.cpp

#include <Adafruit_NeoPixel.h>

#define NEOPIXEL_PIN D5
#define NUM_PIXELS   16
#define LDR_PIN      D1  // A0 on Xiao ESP32-S3

Adafruit_NeoPixel strip(NUM_PIXELS, NEOPIXEL_PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  Serial.begin(115200);
  strip.begin();
  strip.show();  // Initialize all pixels to 'off'
}

void loop() {
  int lightLevel = analogRead(LDR_PIN);  // 0 to 4095
  Serial.print("LDR Value: ");
  Serial.println(lightLevel);

  // Map light level to base hue
  int baseHue = map(lightLevel, 0, 4095, 0, 65535);  // Full 16-bit hue range

  for (int i = 0; i < NUM_PIXELS; i++) {
    // Add hue offset per pixel to create a gradient
    uint16_t hue = (baseHue + (i * 1000)) % 65536;
    uint32_t color = strip.ColorHSV(hue);
    strip.setPixelColor(i, color);
  }

  strip.show();
  delay(100);
}