Auto modification of software means that a computer (PC) changes (and downloads) pic software automatically into a pic. This means a pic can be re-programmed without human intervention.
In this observation one pic is flashing a led. The other pic is equipped with an LDR so it can ‘see’ the LED. It’s objective is to copy the flashing of the LED from the other pic.
In order to do this the pic must be able to distinguish between light and dark, using a threshold value. At the start of the program this threshold value is wrong. By trail and error the computer will determine what the correct threshold value is and modify the program in the pic to reflect this correct value. Yep, right: auto calibration done the hard way!
So, how does the modification process work. At the start of the sequence the computer writes the first version of the pic program to disk. Then it is compiled and downloaded into the pic. The program in the pic looks at the led of the other pic (which is doing nothing, just flashing) and tries to see the difference between light and dark.
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