4. Embedded programming¶
During our group assignment, we all went through several micro-controller boards. Group Assignment - Embedded programming
Board Info¶
Here is the manufacturer spec list of the MKR1010 board I will be using.
| Microcontroller | SAMD21 Cortex®-M0+ 32bit low power ARM® MCU (datasheet) |
| Radio module | u-blox NINA-W102 (datasheet) |
| Board Power Supply (USB/VIN) | 5V |
| Secure Element | ATECC508 (datasheet) |
| Supported Battery | Li-Po Single Cell, 3.7V, 1024mAh Minimum |
| Circuit Operating Voltage | 3.3V |
| Digital I/O Pins | 8 |
| PWM Pins | 13 (0 .. 8, 10, 12, 18 / A3, 19 / A4) |
| UART | 1 |
| SPI | 1 |
| I2C | 1 |
| Analog Input Pins | 7 (ADC 8/10/12 bit) |
| Analog Output Pins | 1 (DAC 10 bit) |
| External Interrupts | 10 (0, 1, 4, 5, 6, 7, 8,9, 16 / A1, 17 / A2) |
| DC Current per I/O Pin | 7 mA |
| CPU Flash Memory | 256 KB (internal) |
| SRAM | 32 KB |
| EEPROM | no |
| Clock Speed | 32.768 kHz (RTC), 48 MHz |
| LED_BUILTIN | 6 |
| USB | Full-Speed USB Device and embedded Host |
| Length | 61.5 mm |
| Width | 25 mm |
| Weight | 32 gr. |
Mu (Circuit-Python Programming)¶
First I started with Python. To get this to work we need to do a few things:- 1- Download Mu Python 2- Download CircuitPython for your specific board 4- Download the latest Library Bundle from CitcuitPython to extend functionality (optional)
To get CircuitPython on our board, we simply need to do the following: 1- Double tap the reset button on the MKR 1010 2- Click and drag the M2U file on the board 3- The device should disconnect and reconnect with CircuitPython ready to go
Last step, open the code.py Mu (file can be found on your MKR 1010 drive). We can simply write our code, and save it, it will then instantly update on the MKR 1010.
I am somewhat familiar with coding but it’s my first time using python, so instead of just simply blinking the LED manually, I wrote a code that takes a morse code text and blinks it automatically.
import board
import digitalio
import time
led = digitalio.DigitalInOut(board.D6)
led.direction = digitalio.Direction.OUTPUT
def blinkLED(code):
duration = 0 #Reset Blink Duration
space = 0.5 #Reset Space Duration
if code == ".": #if Dot
duration = 1
elif code == "-": #if Dash
duration = 2
elif code == " ": #if space, it will count it as a new letter gap
space = 3
time.sleep(space)
if code == "." or code == "-": #if its a morse code, then blink it
led.value = True
time.sleep(duration)
led.value = False
time.sleep(space)
while True:
for x in "... --- ... ---": #Example Morse Code Input. It will break the string into characters
blinkLED(x)
print(x)
Arduino IDE (C Programming)¶
Next we will use the Arduino IDE and write a whole bunch of test code on it. To get started: 1- Download the Arduino IDE 2- Connect the board (you may be prompted to download additional files, which might be required so everything can run)
Blink LED but with randomized values (1 to 5 seconds on button press)¶
Wiring diagram (I used the Uno R3 just for the diagram)
Here is the first example, my comments are found in-line.
int button=0; //Button
int delayTime=1000;
void setup()
{
pinMode(LED_BUILTIN, OUTPUT); //Set the Builtin LED as an Output
pinMode(7,INPUT_PULLUP); //Usually you need to use a resistor to make the button not trigger uncontrollably. However you can also use PullUp feature instead
}
void loop() {
button=digitalRead(7); //Read the button status, 1 is open, 0 is pressed
if(button==0) //check if the button is pressed
{
delayTime=random(1000,5001); //Generate a random number between 1000 and 5000
Serial.println("Button press detected");
}
else //if the button is not pressed, then continue to use the delayTime generated
{
digitalWrite(LED_BUILTIN, HIGH); //Turn on the LED
delay(delayTime); //Set Delay
digitalWrite(LED_BUILTIN, LOW); //Turn off the LED
delay(delayTime); //Set Delay
}
}
LED as Photodiode¶
All LEDs can actually also act as photodiodes, and the same is true of speakers acting as microphones. We can test this by using the LED as an input rather than an output.
int delayTime=1000; //1 second delay
int light=0; //initialize the light value
void setup()
{
pinMode(LED_BUILTIN, INPUT); //set the builtin LED as an input (photodiode)
}
void loop()
{
light=analogRead(LED_BUILTIN); //read the value at the LED
delay(delayTime);
Serial.println(light);
}
Morsecode on button press¶
int button=0;
void setup()
{
pinMode(LED_BUILTIN, OUTPUT);
pinMode(5,INPUT_PULLUP);
}
void loop()
{
button=digitalRead(5);
if(button==0)
{
dotPulse(); //Made the dot and dash functions to simplify the code
dotPulse();
dotPulse();
delay(3000);
dashPulse();
dashPulse();
dashPulse();
delay(3000);
dotPulse();
dotPulse();
dotPulse();
delay(3000);
}
}
void dotPulse()
{
digitalWrite(LED_BUILTIN, HIGH); //Turn on the LED
delay(1000);
digitalWrite(LED_BUILTIN, LOW); //Turn off the LED
delay(500);
}
void dashPulse()
{
digitalWrite(LED_BUILTIN, HIGH); //Turn on the LED
delay(2000);
digitalWrite(LED_BUILTIN, LOW); //Turn off the LED
delay(500);
}
User Defined LED Blink (using serial monitor)¶
int delayTime=1000; //initialize the delay timer
void setup()
{
pinMode(4, OUTPUT);
}
void loop()
{
delayTime = Serial.parseInt(); //take the user input from the serial monitor and convert it into a number
digitalWrite(4, HIGH);
delay(delayTime);
digitalWrite(4, LOW);
delay(delayTime);
}
Full Word to Morse Code app (with visualizer in the Serial Monitor)¶
I wrote this final app to make it work with any word (alphabet letters only, but it can easily be extended further). This code doesn’t catch errors..etc as it’s just a quick fun code I wrote.
Wiring Diagram
String keyWord=""; //Variable to store the current keyword entered
int buzzer=6; //setting the buzzer pin
int longBlink=400; //all these values can be easily customized
int shortBlink=50;
int letterDelay=350; //if the delay is too fast the buzz is not heard clearly
char letters[]= {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'}; //This is so we can get the index number of the letter
//This is the Alphabet morse code, it can easily be extended further
char morseCode[26][4] = {
{'1','2','0','0'}, //A
{'2','1','1','1'}, //B
{'2','1','2','1'}, //C
{'2','1','1','0'}, //D
{'1','0','0','0'}, //E
{'1','1','2','1'}, //F
{'2','2','1','0'}, //G
{'1','1','1','1'}, //H
{'1','1','0','0'}, //I
{'1','2','2','2'}, //J
{'2','1','2','0'}, //K
{'1','2','1','1'}, //L
{'2','2','0','0'}, //M
{'2','1','0','0'}, //N
{'2','2','2','0'}, //O
{'1','2','2','1'}, //P
{'2','2','1','2'}, //Q
{'1','2','1','0'}, //R
{'1','1','1','0'}, //S
{'2','0','0','0'}, //T
{'1','1','2','0'}, //U
{'1','1','1','2'}, //V
{'1','2','2','0'}, //W
{'2','1','1','2'}, //X
{'2','1','2','2'}, //Y
{'2','2','1','1'}, //Z
};
void setup()
{
Serial.begin(9600);
pinMode(LED_BUILTIN, OUTPUT);
pinMode(buzzer,OUTPUT); //buzzer pin set to output
}
void loop()
{
while (Serial.available() == 0) //Wait for a user input
{
}
keyWord=Serial.readString(); //Parse the value as a string
MorseCodeMatch(keyWord); //send to our function
}
void MorseCodeMatch(String keyWord)
{
keyWord.toLowerCase(); //to avoid any issues with case sensitivity
int wordLen=keyWord.length()+1;
char keyChar[wordLen]; //create a character type value array, of the length of the word we are processing
keyWord.toCharArray(keyChar,wordLen); //Break the string into characters
for (int i=0; i<wordLen;i++) //go through each letter of the kerWord
for (int j=0; j<sizeof(letters);j++) //go through the alphabet to find that letter.
if(keyChar[i]==letters[j]) //trying to match it
blinkCodeLED(morseCode[j]); //send the letter to be blinked
Serial.println("morseCode Function Done");
}
void blinkCodeLED(char morseMessage[])
{
for (int i=0;i<4;i++) //Length of the Morse code per letter is 4, so loop 4 times
{
if(morseMessage[i]=='1') //if Dot
{
digitalWrite(LED_BUILTIN, HIGH);
tone(buzzer, 5000, shortBlink);
Serial.print("."); //Dot
}
else if(morseMessage[i]=='2') //if Dash
{
digitalWrite(LED_BUILTIN, HIGH);
tone(buzzer, 5000, longBlink);
Serial.print("-"); //Dash
}
digitalWrite(LED_BUILTIN, LOW); //Reset LED and put a delay between letters
delay(letterDelay);}
Serial.print(" "); //Space
delay(500);
}