6. Embedded Programming

That's how we call the programms dedicated to the management of the microcontroller. For this week, we must use different languages with the translation of the same code with the aim of comparing their efficiency.

The other task requires understanding the characteristics of microcontrollers working in group, the complete documentation is found at the fablab Puebla page.

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I remember reading somewhere that there's an issue with circuitpython and the total usable memory is reduced to 1MB because of a missmatch with the real language space usage.

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The components for this week.

Using the PCB with the Seeed studio rp2040 i have: 3 working diodes with the correct resistor, 1 NEOPIXEL integrated that should always work, 2 buttons( one is soldered on the PCB, for the other one used the pins and female cables), 2 PC buzzer that were part of my father waste before and my cat as emotional support.

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Working with circuitpython

This week final code in circuitpython to download: code.py and the folder with the sounds sounds.zip.

I started the investigation with this language thanks to the circuitpython Essentials, In this page you can find what you need to build almost everything, then in the same learn adafruit page there's more complex task for circuitpython like this multi-tasking-with-circuitpython or debouncer-library-python-circuitpython-buttons-sensors.

For this week the first thing to do is learning to manipulate-interact-get to the components of the PCB, so with Mu editor opened i've created the next code:

# Import section
import board, time, digitalio, pwmio, neopixel
from audiocore import WaveFile
from audiopwmio import PWMAudioOut as AudioOut

# Audio buzzer section
audio1 = AudioOut(board.D2)
audio2 = AudioOut(board.D9)
path= "sounds/"
# Led section
led = digitalio.DigitalInOut(board.D6)
led.direction = digitalio.Direction.OUTPUT
led1 = digitalio.DigitalInOut(board.D7)
led1.direction = digitalio.Direction.OUTPUT
led2 = digitalio.DigitalInOut(board.D0)
led2.direction = digitalio.Direction.OUTPUT
# Buttons section
button = digitalio.DigitalInOut(board.D8)
button.direction = digitalio.Direction.INPUT
button.pull = digitalio.Pull.UP
button2 = digitalio.DigitalInOut(board.D1)
button2.direction = digitalio.Direction.INPUT
button2.pull = digitalio.Pull.UP
# Neopixel section
neopin = board.NEOPIXEL
num_pixels = 1
pixels = neopixel.NeoPixel(neopin,num_pixels, brightness=0.3, auto_write=False)


def color_chase(color, wait):
    for i in range(num_pixels):
        pixels[i] = color
        time.sleep(wait)
        pixels.show()
    


def rainbow_cycle(wait):
    for j in range(255):
        for i in range(num_pixels):
            rc_index = (i * 256 // num_pixels) + j
            pixels[i] = colorwheel(rc_index & 255)
        pixels.show()
        


RED = (255, 0, 0)
YELLOW = (255, 150, 0)
GREEN = (0, 255, 0)
CYAN = (0, 255, 255)
BLUE = (0, 0, 255)
PURPLE = (180, 0, 255)

# Functions section
def play_sound(filename, texit,butto):
    with open(path + filename, "rb") as wave_file:
        wave = WaveFile(wave_file)
        texit.play(wave)
        print(f"Playing {filename}")
        
        texit.pause()
        print("Waiting for button press to continue!")
        while butto.value:
            pass
        texit.resume()
        while texit.playing:
            if led.value == False:
                led.value = True
            else:
                led.value = False
            if led2.value == False:
                led2.value = True
            else:
                led2.value = False
            if led1.value == True:
                led1.value = False
            else:
                led1.value = True

        print("Done!")
# Loop section
x = True
while x:

    color_chase(RED, 0.1)  # Increase the number to slow down the color chase
    color_chase(YELLOW, 0.1)
    color_chase(GREEN, 0.1)
    color_chase(CYAN, 0.1)
    color_chase(BLUE, 0.1)
    play_sound("buop.wav", audio2,button)
    play_sound("wand.wav", audio1,button2)
				
				

This first code should show the entirity of the components working when pressing the 2 buttons, however there's one button doing nothing, and the program suddenly stop.

After an information odyssey and an electronics class, it turns out I dared to assume that I could connect a button to the ground, fortunately nothing serious happened when I landed the PCB and the ground. So I had the option of opening another door of my microcontroller or connecting another pin to the 3V path, I connected another pin.

For the other components: the buzzers obviously they're connected to the ground in the black wire, while the red is where the information will be sent, if it were a larger speaker would have another that would function as direct power.

To get the different sounds i found this website for short sounds, then to convert them to .wav or reduce the frequency to 22k i used the audacity software. The next code shows all the components and functions working as intended.

# Import section
import board, time, digitalio, pwmio, neopixel
from audiocore import WaveFile
from audiopwmio import PWMAudioOut as AudioOut
from rainbowio import colorwheel
# Audio buzzer section
audio1 = AudioOut(board.D2)
audio2 = AudioOut(board.D9)
path= "sounds/"
# Led section
led = digitalio.DigitalInOut(board.D6)
led.direction = digitalio.Direction.OUTPUT
led1 = digitalio.DigitalInOut(board.D7)
led1.direction = digitalio.Direction.OUTPUT
led2 = digitalio.DigitalInOut(board.D0)
led2.direction = digitalio.Direction.OUTPUT
# Buttons section
button = digitalio.DigitalInOut(board.D1)
button.direction = digitalio.Direction.INPUT
button.pull = digitalio.Pull.DOWN
button2 = digitalio.DigitalInOut(board.D8)
button2.direction = digitalio.Direction.INPUT
button2.pull = digitalio.Pull.DOWN
# Neopixel section
neopin = board.NEOPIXEL
num_pixels = 1
pixels = neopixel.NeoPixel(neopin,num_pixels, brightness=0.3, auto_write=False)

def color_chase(color, wait):
    for i in range(num_pixels):
        pixels[i] = color
        time.sleep(wait)
        pixels.show()
    

def rainbow_cycle(wait):
    for j in range(255):
        for i in range(num_pixels):
            rc_index = (i * 256 // num_pixels) + j
            pixels[i] = colorwheel(rc_index & 255)
        pixels.show()
        

#Define colors for color_chase
RED = (255, 0, 0)
YELLOW = (255, 150, 0)
GREEN = (0, 255, 0)
CYAN = (0, 255, 255)
BLUE = (0, 0, 255)
PURPLE = (180, 0, 255)
# Functions section
def play_sound(filename, sndexit,butto):
    with open(path + filename, "rb") as wave_file:
        wave = WaveFile(wave_file)
        sndexit.play(wave)
        print(f"Playing {filename}")
        sndexit.pause()
        print("Waiting for button press to continue!")
        while not butto.value:
            pass
        sndexit.resume()
        while sndexit.playing:
            pass
        if led.value == False:
                led.value = True
        else:
                led.value = False
        if led2.value == False:
                led2.value = True
        else:
                led2.value = False
        if led1.value == True:
                led1.value = False
        else:
                led1.value = True    
        print("Done!")
# Loop section
x = True
while x:
    rainbow_cycle(1)
    play_sound("buop.wav", audio2,button)
    play_sound("wand.wav", audio1,button2)
				

Now we can use the components to simulate a car ignition:

# Import section
import board, time, digitalio, pwmio, neopixel
from audiocore import WaveFile
from audiopwmio import PWMAudioOut as AudioOut
from rainbowio import colorwheel
# Audio buzzer section
audio1 = AudioOut(board.D2)
audio2 = AudioOut(board.D9)
path= "sounds/"
# Led section
led3 = digitalio.DigitalInOut(board.D6)
led3.direction = digitalio.Direction.OUTPUT
led1 = digitalio.DigitalInOut(board.D7)
led1.direction = digitalio.Direction.OUTPUT
led2 = digitalio.DigitalInOut(board.D0)
led2.direction = digitalio.Direction.OUTPUT
leds = [ led3,led1,led2]
# Buttons section
button = digitalio.DigitalInOut(board.D1)
button.direction = digitalio.Direction.INPUT
button.pull = digitalio.Pull.DOWN
button2 = digitalio.DigitalInOut(board.D8)
button2.direction = digitalio.Direction.INPUT
button2.pull = digitalio.Pull.DOWN

# Neopixel section
neopin = board.NEOPIXEL
num_pixels = 1
pixels = neopixel.NeoPixel(neopin,num_pixels, brightness=0.3, auto_write=False)

def color_chase(color, wait):
    for i in range(num_pixels):
        pixels[i] = color
        time.sleep(wait)
        pixels.show()
    time.monotonic()

#Define colors for color_chase

Pure_red = (255, 0, 0)
R1 = (230, 26, 0)
R2 = (204, 51, 0)
R3 = (179, 77, 0)
R4 = (153, 102, 0)
R5 = (128, 128, 0)
R6 = (102, 153, 0)
R7 = (77, 179, 0)
R8 = (51, 204, 0)
R9 = (26, 230, 0)
Pure_green = (0, 255, 0)
G1 = (0, 230, 26)
colors = [Pure_red,R1,R2,R3,R4,R5,R6,R7,R8,R9,Pure_green,G1]
colors_count = 0
def getting_ready(filename, sndexit,butto):
    with open(path + filename, "rb") as wave_file:
        wave = WaveFile(wave_file)
        for i in leds:
            sndexit.play(wave)
            print("Setting the engine")
            sndexit.pause()
            print("Waiting for button press to continue!")
            while not butto.value:
                pass
            i.value = True
            sndexit.resume()
            while sndexit.playing:
                while colors and sndexit.playing:
                    color_chase(colors[0],0.2)
                    colors.pop(0)
        print("Engine Set")
        
def lets_get_out(filename, sndexit,butto):
    with open(path + filename, "rb") as wave_file:
        wave = WaveFile(wave_file)
        sndexit.play(wave)
        sndexit.pause()
        print("Waiting for button press to scape!")
        while not butto.value:
            pass
        sndexit.resume()
        while sndexit.playing:
            pass
#Loop Section
getting_ready("car.wav", audio1,button2)
lets_get_out("ready.wav", audio2,button)
				

Video of the result:

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Arduino ide

This week final code in arduino to download: buzzer.ino.

Now that i have more experience with arduino there's some clearly advantages: Adding new boards via the board manager or aditional url manager in the file-preferences tab

And the ease of use of libraries with the library manager or the option to add via zip from github or other sources

Translating the previous code to the C++ arduino language, remember to replace the "" with >, the next code reassemble the circuitpython one, but using simple tones as it isn't as easy to manage flash memmory in arduino:

First we import the libraries with the #include and the name then we use the #define to give a name to the pin and the location i like to use the letternumber direction to avoid issues with many boards, with the execption of the built in things where the manufacturer especify it's pin number.

#include "Adafruit_NeoPixel.h"

// Pin definitions
#define AUDIO_PIN1 D2
#define AUDIO_PIN2 D9
#define LED_PIN3 D6
#define LED_PIN1 D7
#define LED_PIN2 D0
#define BUTTON_PIN1 D1
#define BUTTON_PIN2 D10


// Number of NeoPixels
#define NEOPIXEL_PIN 12
int Power = 11;
#define NUMPIXELS 1

// NeoPixel object
Adafruit_NeoPixel pixels(NUMPIXELS, NEOPIXEL_PIN, NEO_GRB + NEO_KHZ800);
				

In arduino, c, exist a more eficcient way to save resources calling static, unsigned, size of the element, that's why you found many types of int, char, bool, byte, etc..

// Led and button setup
int leds[] = {LED_PIN3, LED_PIN1, LED_PIN2};

// Color definitions
uint32_t colors[] = {
    pixels.Color(255, 0, 0), 
    pixels.Color(230, 26, 0), 
	pixels.Color(204, 51, 0), 
	pixels.Color(179, 77, 0),
    pixels.Color(153, 102, 0), 
	pixels.Color(128, 128, 0), 
	pixels.Color(102, 153, 0),
    pixels.Color(77, 179, 0), 
	pixels.Color(51, 204, 0), 
	pixels.Color(26, 230, 0),
    pixels.Color(0, 255, 0),  
    pixels.Color(0, 230, 26)
};
int colors_count = 0;
int total_colors = sizeof(colors) / sizeof(colors[0]);
				

Instead of the "def" function in python in arduino we have void functions with two special ones, the setup and the loop, it doesn't matter where you place them as the instructions will ever be first the program will run the setup function one time and then run whatever is inside the loop as a loop, in the setup function you usually set the pinMode of the pins, set some digital writes in the OUTPUTS and begin some libraries, also all the parts of the Serial family are used to communicate with the pc by USB.

void setup() {
    // Initialize pins
    pinMode(LED_PIN3, OUTPUT);
    pinMode(LED_PIN1, OUTPUT);
    pinMode(LED_PIN2, OUTPUT);
    pinMode(BUTTON_PIN1, INPUT);
    pinMode(BUTTON_PIN2, INPUT);
    pinMode(Power,OUTPUT);
    digitalWrite(Power, HIGH);

    // Initialize NeoPixel
    pixels.begin();
    pixels.setBrightness(75);
    Serial.begin(9600);

}
				

The fist function is used to change the color of the neopixels in your project.

void color_chase(uint32_t color, int wait) {
    for (int i = 0; i < NUMPIXELS; i++) {
        pixels.setPixelColor(i, color);
        pixels.show();
        delay(wait);
    }
}
				

The first function to prepare the engine as in the previous code with a delay for the loop function to give time for the tone to end, then we wait for the button to be pressed checking every 10 milliseconds, turn one led, play the tone and change the neopixel color until the three leds are on.

void getting_ready(const int toneFrequency, int buttonPin) {
    delay(1000);
    Serial.println("Waiting for button press to continue!");

    while (digitalRead(buttonPin) == HIGH) {
        delay(10);
    }

    for (int i = 0; i < 3; i++) {
        digitalWrite(leds[i], HIGH);
        tone(AUDIO_PIN1, toneFrequency);  // Start playing tone
        for (int j = 0; j < total_colors; j++) {
            color_chase(colors[j], 200);
        }
        noTone(AUDIO_PIN1);  // Stop playing tone
    }

    Serial.println("Engine Set");
}
				

Something similar but intended to play with a different tone to reassemble the sounds in python.

void lets_get_out(const int toneFrequency, int buttonPin) {
    Serial.println("Waiting for button press to escape!");

    while (digitalRead(buttonPin) == HIGH) {
        delay(10);
    }

    tone(AUDIO_PIN2, toneFrequency);  // Start playing tone
    delay(2000);                      // Let the tone play for 2 seconds
    noTone(AUDIO_PIN2);               // Stop playing tone
}
				

At last run the code infinitely, if you want to run it once you can place the functions in setup.

void loop() {
    getting_ready(800, BUTTON_PIN2);  // Tone frequency 800 Hz
    lets_get_out(500, BUTTON_PIN1);    // Tone frequency 500 Hz
}
				

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Final reflection

At first I didn't think about how comfortable it was to work with circuitpython to use the flash as non-volatile storage, since in most pcbs it's normal to use eeprom or a sd memory to store sounds or text files. I think that is one of the strengths of circuit python, in addition to that it is a limiting or advantage as the libraries that already come installed in the .uf2 are practically all you will find, while in arduino there is a much broader documentation for easily programming and installing the boards and libraries created by the community.