Thread: Boot Loaders and Self Programming.

A boot loader is software programmed into the AVR flash memory that will allow the chip to accept and program additional program code from some source. The boot loader depends on the AVRs ability to program its own flash.

If you do not provide an ISP header for each processor you need to program each AVR with the bootloader prior to soldering it to the PCB. But if you mess up and overwrite a boot loader on one of the chips you will be in trouble because you have no way to reprogram the corrupted boot loader. You could buy a very expensive test clip that lets you program the chip on the PCB. I expect they are too expensive to be a possibility.

Having said that I strongly suggest you include some version of an ISP header to reflash you boot loaders.

So basically do the Self Programming features allow you to reprogram the AVRs say by the UART or SPI bus? How does this work, would I upload the new s/w via PC to a Master AVR and then send a command to initiate an update to Slave AVRs via SPI?

Keep in mind that each AVR must reprogram itself using the previously programmed boot loader. The boot loader communicates with some other device which provides the data to be programmed.

If you understand the above you can flash an AVR from an AVR or PC over most any IO channel provided you adjust the boot loader to use that channel.

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This is probe that will attach to 3 adjacent pins on a QFP chip.

Agilent | E2613A 0.5 mm Wedge Probe Adapter for TQFP and PQFP



It is $150 maybe someone has a cheaper knock off. Or maybe your pockets are deep enough.

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