Week 9

Programming the Board

Burn the bootloader to the PCB

In order to burn the bootloader to the PCB, I first needed to install the ATTiny44/A drivers on my laptop.

I used the drivers provided by Adafruit at this link

After installing the drivers, I opened the Arduino IDE, selected the "Tools" menu and navigated to the boards manager.
This can be found when hovering over "Board" , above "Processor".

When the manager window pops up, I filtered the ATTiny boards, by entering attiny in the search bar.

ATTiny boards installed

Now, we can configure the IDE to burn the bootloader to our board and in order to configure the IDE, we need to have read the datasheet at least once in order to understand what we are doing.

The settings are as following:

• Board: ATTiny 24/44/84
• Processor: ATTiny 44
• Clock: 20 MHz
• Programmer: USBtinyISP

Double check, to see if your settings are correct and select Burn Bootloader

I recieved and error, stating that the connections might the issue.

Error burning bootloader.

After checking the solder, it seemed that there was a damaged track. After soldering a piece of leftover Cu, the bootloader was succesfully installed.

Blink the LED

In order to get aquinted with the programming, I opened a few samples, that come with the IDE.

These can be found under the File Examples and built-in examples.

I loaded up the sketch code, just out of curiosity if the LED would do as it is told and sure enough, it was blinking.

Quick look at the code.

Program the LED to turn on or off with a switch/button

Again, you can use the built in examples to learn and understand. Loaded the code up to the board and the LED turned on as long as the button was pressed.

The Button example.

Using the PWM of the ATTiny44

After the examples, I decided to use the PWM for simulating an analog potentiometer. With this I can controll the LED brightness with a few clicks.

I had some issues, with the button not alwasys turning on the LED. I concluded that it was a button bounce, which created this and used a bool (true,flase) param, in order to elimante this.

Here is the code in text:

int switchPin = 3;
int ledPin= 8;
boolean lastButton = LOW;
boolean currentButton = LOW;
int ledLevel = 0;

void setup()
{
  pinMode(switchPin, INPUT)
  pinMode(ledPin, OUTPUT);
}

boolean debounce(boolean last)
{
  boolean current = digitalRead(switchPin);
  if (last != current)
{
  delay(5);
  current = digitalRead(switchPin);
}
return current;
}

void loop()
{
  currentButton = debounce(lastButton);
  if (lastButton == LOW && currentButton == HIGH)
{
  ledLevel = ledLevel + 51;
}
lastButton = currentButton;

if (ledLevel > 255) ledLevel = 0;
analogWrite(ledPin, ledLevel);
}
                    

And here is the .ino download link:

The PWM Code

Hilfe Mich. Programming the LED to flash S.O.S Morse

I wanted the LED to flash Morse code, S.O.S and in order to do that I first had to read up on the conventions of Morse Code.

Morse Alphabet.

//SOS for LED, when pressed by Button:
int ledPin = 8;
int switchPin= 3;
int val = 0;
int s = 300;
int o = 800;

void setup() {
  pinMode(ledPin, OUTPUT);
  pinMode (switchPin, INPUT);
}

void character(int speed) {
  digitalWrite(ledPin, HIGH);
  delay(speed);
  digitalWrite(ledPin, LOW);
  delay(300);
}

void loop() {
  val = digitalRead(switchPin);
  if (val==HIGH) {
  digitalWrite(ledPin, LOW);
  for (int x = 1; x <= 3; x++) {
  character(s);
}
delay(100);
for (int x = 1; x <= 3; x++) {
  character(o);
}
delay(100);
for (int x = 1; x <= 3; x++) {
  character(s);
}
delay(2000);
}
else{
  digitalWrite(ledPin,LOW);
}
}
                    

I will go a bit into detail how I wrote the code and how some statements have been used.

The “for” statement
The “for” statement is used to repeat a block of statements enclosed in brackets. An increment counter is usually used to increment and terminate the loop. The “for” statement is useful for any repetitive operation, and is often used in combination with arrays to operate on collections of data/ pins.
There are three parts to the “for” loop header:

• Initialization
• Condition
• Statement

So for the “for“ statement in the sketch:

for(int x = 1; x < 3; x++){

}
                                      

Step 1: Integer (whole numbers) value of variable x as 1
Step 2: Evaluate if x is less than 3.
Step 3: If it is valid, execute the following statement
Step 4: x increases and becomes 2.
Step 5: Repeat Step 2 less than 3.
Step 6: Repeat step 3
Until x = 3, the condition of x < 3 is not valid then the program skips over the code.
We set x < 3 to have it repeat 3 times. Calculating from 0 to 2, it repeats 3 times.
If we wanted it to repeat 100 times, we can use the following code: for(int x = 0;x < 100;x++){}
Some comparison operators like ">", " < " are frequently used in programming conditional statements. They will covered in more detail in the next section.

This is a section of a tutorial found here: DFrobot blog

I combined the button code with the Blink code, in order to flash SOS whenever the button is pressed.

Download the The SOS Code here.

Embed C using VSCode and PlatformIO

I decided, that the Arduino IDE is a good way to code for your Arduino based platform, but wanted to know if there was an alternative with VSCode, just to keep it in line with one IDE.

Surely enough an online search brought me to PlatformIO

This is an open source ecosystem fo IoT development in mind. It is cross-platform so jumping from OS to OS makes it much easier for IoT developers.

In order to install it, I could just lookup PlatformIO in the extensions section of VSCode, install it and run it.

Install PlatformIO VSCode.

Create New Project

Select the MCU, Framework and of course the name of your project

Wait for Initialization to complete.

Initialization completed.

Now we can code the code, that we want to upload to the board. This uses c/cpp extensions.

It is rather quick to upload your code to your board as it is mostly automated process, but for sanity and a more granular control's sake, we can always edit the config if and when needed.

Wait for Initialization to complete.