I just start to study arduino, and I find when using the blink program, the LED in PCB pin13 is blinking. and find on the schematic, PCB pin13 is connect to IC PB5 from resistor, I want to know how the pin13 is relative to PB5 in program?
I moved your topic to an appropriate forum category @leoleixm.
In the future, please take some time to pick the forum category that best suits the subject of your topic. There is an "About the _____ category" topic at the top of each category that explains its purpose.
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Thanks in advance for your cooperation.
The compiler/IDE "knows" how the chip is wired to the pins on the circuit board.
The compiled machine code actually running inside the chip doesn't use "pin 13" directly.
It also knows how to "map" or "abstract" LED_BUILTIN to a particular pin on the chip. These are features of the Arduino version of C++. If you were writing assembly code or if you were using a complier from Atmel, Pin 13 and LED-BUILTIN wouldn't be defined and wouldn't work,
@DVDdoug ok, got it, Thanks!