[Tutorial] Burning Arduino bootloader to MRD20 Tinium8T (ATtiny85)

The following section illustrates the guidance steps for burning Arduino bootloader to MRD20 Tinium8T (ATtiny85) via MRP01 AVR USB Programmer:

1. Update the Avrdude programming firmware into MRP01 AVR USB Programmer by following instruction at user manual at this link(MRP01 AVR USB Programmer/MRP01 User Manual.pdf).
2. Disconnect MRP01 from laptop or desktop.
3. Download and install the latest Arduino software from this link if it is not yet installed.
4. Download the ATiny master.zip from this link .
5. Identify Arduino sketchbook folder by checking its location in the preferences dialog at Arduino software, as follows:
   
6. Create a new folder named “hardware” in the sketchbook folder if it doesn't exist yet.
7. Extract the "ATtiny master.zip" file and copy "attiny" folder(which is inside unzipped "attiny-master" folder) into “hardware” folder as follows:
   
8. Connect MRP01 ISP output to MRD20.
9. Connect MRP01 to desktop or laptop.
10. Restart the Arduino IDE.
11. Select [Tools] > [Board] > [Attiny85 (internal 1Mhz)]  if user is using internal oscillator 1Mhz.
    
12. Click [Tools] > [Burn Bootloader] and user can see the successful message "Done burning bootloader" when bootloader is uploaded to ATtiny85.
    

Change external oscillator value in Arduino hardware configuration

If user wants to use the provided 16Mhz resonator, user needs to do some modifications on the attiny board configuration file. The easiest way is to modify the [ATtiny85 (external 20 MHz clock)] example as follows:

1. First, open the "board.txt" inside the [attiny] folder copied to [hardware] folder as above.
2. Change the two source lines as below:
1. Change "attiny85-20.name=ATtiny85 (external 20 MHz clock)" to "attiny85-20.name=ATtiny85 (external 16 MHz clock)"
2. Change "attiny85-20.build.f_cpu=20000000L" to "attiny85-20.build.f_cpu=16000000L"
3. Save the changes at board.txt file.
4. Restart the Arduino IDE and user can burn the Arduino bootlader with 16Mhz external oscillator setting to ATtiny85.