How to Use ATTiny85: Examples, Pinouts, and Specs

The ATTiny85 is a small, low-power microcontroller from Atmel's AVR family, designed for embedded systems and DIY electronics projects. It features an 8-bit architecture, 8 KB of flash memory, 512 bytes of SRAM, and 6 I/O pins, making it a versatile choice for compact and low-power applications. Its small size and ease of programming make it a popular choice among hobbyists and professionals alike.

• Wearable electronics
• IoT (Internet of Things) devices
• LED control and lighting systems
• Sensor-based projects
• Small robotics and automation systems
• Battery-powered devices

The ATTiny85 is a highly capable microcontroller with the following key specifications:

The ATTiny85 comes in an 8-pin package. Below is the pinout and description:

The ATTiny85 is a versatile microcontroller that can be programmed using the Arduino IDE or other AVR programming tools. Below are the steps to use the ATTiny85 in a circuit:

1. Setup the Arduino IDE:

   • Install the ATTiny85 board package in the Arduino IDE by adding the following URL to the "Additional Board Manager URLs" in the preferences:
     https://raw.githubusercontent.com/damellis/attiny/ide-1.6.x-boards-manager/package_damellis_attiny_index.json
   • Go to "Tools > Board > Boards Manager" and install the "ATTinyCore" package.

2. Connect the ATTiny85 to a Programmer:

   • Use an Arduino UNO as an ISP (In-System Programmer) or a dedicated USB programmer.
   • Connect the pins as follows:

     Arduino UNO Pin	ATTiny85 Pin
     10 (RESET)	Pin 1 (RESET)
     11 (MOSI)	Pin 2 (PB3)
     12 (MISO)	Pin 3 (PB4)
     13 (SCK)	Pin 5 (PB0)
     GND	Pin 4 (GND)
     5V	Pin 8 (VCC)

3. Select the Board and Programmer:

   • In the Arduino IDE, go to "Tools > Board" and select "ATTiny85".
   • Set the clock speed (e.g., 8 MHz internal oscillator).
   • Choose the programmer (e.g., "Arduino as ISP").

4. Upload Code:

   • Write your code in the Arduino IDE and upload it to the ATTiny85 using "Sketch > Upload Using Programmer".

The following example demonstrates how to blink an LED connected to Pin 0 (PB0) of the ATTiny85:

// Blink an LED on ATTiny85 Pin 0 (PB0)

#define LED_PIN 0  // Define the LED pin (PB0)

void setup() {
  pinMode(LED_PIN, OUTPUT);  // Set the LED pin as an output
}

void loop() {
  digitalWrite(LED_PIN, HIGH);  // Turn the LED on
  delay(500);                   // Wait for 500 milliseconds
  digitalWrite(LED_PIN, LOW);   // Turn the LED off
  delay(500);                   // Wait for 500 milliseconds
}

• Power Supply: Ensure the ATTiny85 is powered within its operating voltage range (2.7V - 5.5V).
• Clock Source: By default, the ATTiny85 uses an 8 MHz internal oscillator. For higher speeds, an external crystal or resonator is required.
• Pull-Up Resistors: If using the RESET pin as a GPIO, disable the reset functionality in the fuse settings and use a pull-up resistor.

1. Problem: The ATTiny85 is not detected by the programmer.
   Solution:

   • Check the wiring between the programmer and the ATTiny85.
   • Ensure the correct board and programmer are selected in the Arduino IDE.
   • Verify that the ATTiny85 is powered correctly.

2. Problem: The uploaded code does not run as expected.
   Solution:

   • Double-check the pin assignments in your code.
   • Ensure the correct clock speed is selected in the Arduino IDE.

3. Problem: The LED does not blink in the example code.
   Solution:

   • Verify that the LED is connected to the correct pin (PB0).
   • Check the polarity of the LED and the resistor value (e.g., 220Ω).

• Can I use the ATTiny85 with I²C sensors?
  Yes, the ATTiny85 supports I²C communication using the USI (Universal Serial Interface). Libraries like TinyWire can simplify I²C communication.

• How do I reset the ATTiny85 to factory settings?
  Use a high-voltage programmer to reset the fuse bits to their default values.

• Can I use the ATTiny85 for battery-powered projects?
  Yes, the ATTiny85 is ideal for low-power applications. Use sleep modes to conserve power when the microcontroller is idle.