Attiny85 is locked, how to recover ?
Hedy · Dasenic Content Editor
Published Sep 26,2024If 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