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Old 10-06-2009, 12:19 AM   #2370 (permalink)
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Originally Posted by bones007 View Post
I have a question about how the bootloader works. When you use the bootloader to re-program the microcontroller does your new code have to include the bootloader itself each time?

Or is the bootloader protected somehow such that you can upload a program with flaws, fix the program and upload again without screwing up the bootloader.
The bootloader is protected somehow! hehe. You just have to program the chip with the bootloader one time, using something like an STK500 or a homemade programmer, and then after that, you never again need to worry about it.

I think you should make sure that R15 is 220 Ohms, and R16 is either 4.7 kOhms or 6.8 kOhms. When I first did a couple control boards, I was using 330 Ohm and 3kOhm, which can be fine, but it depends on the optocoupler that is used. There's a lot of variation from optocoupler to optocoupler, even with the same part number. Using 220 and 6.8 K garantees that it will turn on and off really fast. Alternatively, I would use metal end caps with rubber grommits.
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