Week 7

Programming the Board

After soldering the board, what next?

After I soldered the board, according to the design, we test and see if the board is funtioning correctly, We used a mulitmeter to check.

The con with using only a multimeter, is if things are not connected properly, you cannot see it on the meter.

This is one of the reasons, I could not burn my bootloader at first try, but more on that later.

I read up on the datasheet for the ATTiny44A in order to locate the Pulse Width Modulation Pin.

I used pin 8 for the PWM and LED, so whenever Pin 3 gets activated by the button/switch, I can use the PWM feature of pin 8 via Arduino IDE

The Pin Layout of the ATTiny44A

Locating the PWM Pins

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

Troubleshooting

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.

Also always check to postion of your VCC and GND pins. Switching them around, only creates unnecessary stress.

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.

At first I did not understand how the PWM code worked, so I looked up a tutorial from Jeremy Blum

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

I did not edit the code, just for educational reasons, to better understand the code.

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.