Why use bootloader in ATtiny85 ?

Hi Friends,

I have successfully programmed ATtiny85 using Arduino MEGA.

I used instructions of this link,

According to above link, need to burn bootloader. But,I was able to upload the Blink code without burning bootloader also.

But, Blinking speed is different.
ATtiny85 without bootloader has slower blinking speed than other one. The ATtiny85 which has bootloader is correctly Blinking.(It shows given delay).

What is the reason for that?
What is the relationship between Cycle frequency of ATtiny85 and the bootloader?

Nandika:
Hi Friends,

I have successfully programmed ATtiny85 using Arduino MEGA.

I used instructions of this link,

Programming ATtiny85 with Arduino Uno - Arduino Project Hub

According to above link, need to burn bootloader. But,I was able to upload the Blink code without burning bootloader also.

But, Blinking speed is different.
ATtiny85 without bootloader has slower blinking speed than other one. The ATtiny85 which has bootloader is correctly Blinking.(It shows given delay).

What is the reason for that?
What is the relationship between Cycle frequency of ATtiny85 and the bootloader?

The "burn bootloader" sets the fuses to properly set the speed of the chip

When the chip leaves the factory the fuses are set for an internal 8 MHz RC clock and an initial clock pre-scale of 8. That means that until you change the fuses (using Burn Bootloader) the chip runs at 1 MHz. The Arduino core expects it to be running at 8 (or maybe 16) MHz.

That means 'Burn Bootloader' changes pre-scale to 1 ?

Nandika:
That means 'Burn Bootloader' changes pre-scale to 1 ?

Yes. It clears the fuse that says "set the prescale to 8 on reset". It is probably also setting some of the other configuration fuses, like the brownout detection level and such.

Thank you very much for all information. :slight_smile: