If ATTiny85 is locked, it is usually because programming protection (such as write protection) is enabled. How can we recover it.

First, let's understand the structure of ATTiny85

ATtiny85 is a small 8-bit AVR microcontroller produced by Atmel (now Microchip Technology), widely used in embedded systems and low-power projects. ATtiny85 has 8 KB of flash memory, 512 bytes of SRAM, and 6 programmable I/O pins.

ATtiny85 usually has 8 pins, and the main functions include:

Pin 1 (RESET): reset pin.

Pin 2 (PB3): can be used as input/output, PWM output.

Pin 3 (PB4): can be used as input/output, PWM output.

Pin 4 (GND): ground.

Pin 5 (VCC): power supply.

Pin 6 (PB0): can be used as input/output, ADC input.

Pin 7 (PB1): Can be used as input/output, ADC input.

Pin 8 (PB2): Can be used as input/output, ADC input.

For more details, please check the official attiny85 datasheet

If the ATTiny85 is locked, to recover it, you can try the following steps:

Use the correct programmer:

Make sure the programmer you use (such as USBasp or AVRISP mkII) supports ATTiny85 and the driver is installed correctly.

Try the unlock command:

Use the programming software (such as AVRdude) to send the unlock command. You can try the following command:

avrdude -c usbasp -p t85 -B1 -e

Where -e means erase the entire chip, which may clear the locked state.

Check the wiring:

Make sure the wiring between the programmer and the ATTiny85 is correct, including MISO, MOSI, SCK, RESET and GND.

Change the frequency:

Sometimes, the programmer's clock frequency is not set correctly, which may cause communication failure. Try using a lower frequency.

If the above method does not work, you may need to reburn the bootloader or use a dedicated unlocking tool.

Reburn the bootloader:

Attiny85 programming with arduino

Hardware connection:

Use Arduino UNO or other compatible Arduino board as a programmer.

Connect the ATtiny85 to the Arduino, usually using the 6-pin or 10-pin programming interface.

Install Arduino IDE:

Make sure to install the latest version of Arduino IDE.

Add ATtiny85 support:

In Arduino IDE, open "File" > "Preferences".

In "Additional Development Board URLs", add the following URL:

http://digistump.com/package_digistump_index.json

Go to "Tools" > "Development Board" > "Development Board Manager", search and install "Digistump AVR Boards".

Select the board and chip:

Select "ATtiny85" as the target board in the Tools menu and set the relevant options, such as the clock frequency (usually 8 MHz or 16 MHz).

Write code:

Write Arduino code (C/C++) to use the ATtiny85's pins to control sensors, LEDs or other peripherals.

Upload code:

In the Arduino IDE, select "Arduino as ISP" as the programmer and click Upload code.

Attiny85 Program and Burn Bootloader using Arduino

ATtiny85 Project Example

LED flashing:

void setup() {
pinMode(0, OUTPUT); // Set pin 0 as output
}
void loop() {
digitalWrite(0, HIGH); // Turn on LED
delay(1000); // Delay 1 second
digitalWrite(0, LOW); // Turn off LED
delay(1000); // Delay 1 second
}

Temperature sensor reading:

Use ATtiny85 to connect a temperature sensor (such as LM35), read analog values ​​and control a fan or other device through PWM.

Attiny85 Program and Burn Bootloader using Arduino

ATtiny85 is a powerful and flexible microcontroller that can be used with the Arduino platform to easily implement a variety of projects. Whether it is simple LED control or complex sensor integration, ATtiny85 can do it, especially suitable for low-power and space-constrained application scenarios.

ATtiny85 Series Microcontrollers