Well, the bootloader is to enable serial communication through USB ?
Again, no.
The bootloader allows you to program the micro using the serial pins. That doesn't specifically mean it has to be done through USB. Also, just because the bootloader is not on there, doesn't mean it can't be programmed through USB (See USB ICSP Programmers).
Not to change the fuse bits so as to use the external 16MHz crystal ?? LOL
Burning the bootloader is the Arduino way of changing the fuse bits. It can be done in AVR Studio without burning the bootloader. I don't see the big deal in burning the bootloader on there just to set the fuse bits. Unless you are programming it using the bootloader (meaning using the serial pins), then the bootloader will get wiped out the next time you program it.
How can I know that 2kb is used for the bootloader file ? I want to see for the difference when I upload bootloader and remove bootloader but I cant see it ><
I mean for the total available size for the sketch. When I burn bootloader, the chip memory would be reduced by approximate 2kb right ? But where can I see it ?
Vincent19:
How can I know that 2kb is used for the bootloader file ? I want to see for the difference when I upload bootloader and remove bootloader but I cant see it ><
See the difference in what? The size? Add 2K if you are using the bootloader to upload the sketch, don't if you are not.
In the same vein, I have a similar question but not so technical. I ended up blasting the analog channels and now I get "processor out of sync" and it won't accept a program or run the existing one. Clearly this is bad. If I install a new Atmega328 chip on the card, (assuming that nothing else is destroyed), can I program it in-situ using the Arduino software and get a working unit once more? Just curious. The chips are only a couple of bucks versus a new card being 20-30 dollars.
thorargent:
In the same vein, I have a similar question but not so technical. I ended up blasting the analog channels and now I get "processor out of sync" and it won't accept a program or run the existing one. Clearly this is bad. If I install a new Atmega328 chip on the card, (assuming that nothing else is destroyed), can I program it in-situ using the Arduino software and get a working unit once more? Just curious. The chips are only a couple of bucks versus a new card being 20-30 dollars.
Thanks.
Yes, assuming no other components got zapped a simple replacement of the 328p chip will get you operational, that's one of the greatest advantages of a arduino board that uses a socketed DIP uP chip. However to save you some greef if you haven't already learned how to burn bootloaders onto blank chips or if you don't own a hardware programmer or a second functioning arduino board I would suggest you buy your chip with a bootloader already burned into the chip for just a few dollars more. SparkFun has them as well as other speciality vendors.