Tuesday, February 21, 2012

AT90USBKEY: LED blink program

Here is a small program to get started with AT90USBKEY. This AVRGCC code will make the 4 LED's on board blink. You can download the entire AVR Studio 5 project folder from here.

Sometimes you may get stuck with the line

clock_prescale_set(clock_div_1);


This line is included to clear the system clock prescaler. AT90USBKEY boards are shipped with their CKDIV8 fuse programmed. This will divide the system clock by a factor of eight during start up and it will remain so unless we clear it manually.  AT90USBKEY on board crystal is 8MHz but controller will be running only at 1 MHz. So to clear up this issue we used the above function. 

1 comments:

Felipe Duque said...

Hi there. I couldn't see any code! :)

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