The ATTINY44 is a low power AVR® 8-bit microcontroller based on the RISC architecture.It have 12 GPIO pin's. The Atmel ATtiny24/44/84 provides the following features: 2/4/8K bytes of in-system programmable flash, 128/256/512 bytes EEPROM, 128/256/512 bytes SRAM, 12 general purpose I/O lines, 32 general purpose working registers, an 8-bit Timer/Counter with two PWM channels, a 16-bit Timer/Counter with two PWM channels, internal and external interrupts, an 8-channel 10-bit ADC, programmable gain stage (1x, 20x) for 12 differential ADC channel pairs, a programmable watchdog timer with internal oscillator, internal calibrated oscillator, and three software selectable power saving modes. The best way to know about a microcontroller and Instruction set is reading its Datasheet.we will get all the information from the Datasheet , only problem is that its not beginner friendly.

With the help of the tutorial https://www.gadgetronicx.com/attiny85-gpio-input/ I tried how to get started with this 8 bit MCU, Attiny85 and how to use its GPIO pin as an output, how to configure its GPIO pins as input and how to read status of input pin. Here I used a push button to feed signal to digital input pin and a LED as output. The LED state will be toggled based on the button input.

The configuration of ATTiny85 GPIO input pins starts with DDRB register, you can refer the datasheet here. I used pin 2 of ATTiny85 as Input. Now according to the datasheet the pin 2 is PB3 of PORTB. In order to make it as an Input we need to write the DDB3 register bit as logic ‘low’ or 0 in the code. The below piece of code will do that.

DDRB &= ~(1 << PB3); // Set the pin PB3 as input

Similarly we need to define the pin 3 or PB4 as an output pin. Therefore the DDB4 register bit will be logic ‘high’ or 1. DDRB |= (1 << PB4); // Set the pin PB4 as output

Preparing the Schematic & Board for milling

STEPS FOR PROGRAMING & CODING FOR BLINKING OF LED

1. First of all in arduino IDE i Had to add ATtiny 44 Board to program my board:

2. Open Ardiuno IDE click File-> Prefrences

3. URL to add to the ‘Additional Boards Manager URLs’ field: https://raw.githubusercontent.com/damellis/attiny/ide-1.6.x-boards-manager/package_damellis_attiny_index.json

3. After adding the URL open Board Manager by clicking Tools >> Board >> Board Manager

4. Search for ATtiny44 in the following Window.(Make sure you have Internet connection).and Install the latest version.

5. Now you can select ATtiny44 under the ATtiny Microcontrollers in board Selection6Select the Clock as 20MHz.

6. Select the Clock as 20MHz.

7. We are using Fab ISP to programme the Hello-Echo board, so Select the Programmer as USBtinyISP.

8. Now Write the code in the in the ardiuno IDE

Blinking LED

Toggle LED

void setup() {
#define LED 8
#define SW 7
void setup()
{
pinMode(LED, OUTPUT);
pinMode(SW, INPUT);
}
void loop()
{
digitalWrite(LED, HIGH);
delay(1000);
digitalWrite(LED, LOW);
delay(1000);
}

====================

LED Pull Up

====================

const int ledPin = 7;

int BUTTONState = 0;

void setup()
{
pinMode(PA2, OUTPUT);
pinMode(PB2, INPUT_PULLUP);
}

void loop()
{
BUTTONState = digitalRead(PB1);
if (BUTTONState == 0
)
{
digitalWrite(PA2, LOW);
}
else
{
digitalWrite(PA2, HIGH);
}
}

#define LED PA2
#define SW  PA6

// toggle the led status upon button press

boolean prev_btn_stat=HIGH;
boolean prev_led_stat=LOW;
boolean current_btn_stat;

void setup() {
// put your setup code here, to run once:
pinMode(LED,OUTPUT);
digitalWrite(LED,LOW);
pinMode(SW,INPUT_PULLUP);
}

void loop()
{
prev_btn_stat = current_btn_stat;
current_btn_stat = digitalRead(SW);
if(!current_btn_stat && (current_btn_stat != prev_btn_stat) )
{
delay(5);   //debouncing with 1ms delay
if ( prev_led_stat )
{
digitalWrite(LED,LOW);
prev_led_stat = LOW;
}
else
{
digitalWrite(LED,HIGH);
prev_led_stat = HIGH;
}
}

//delay(200);
}