Arduino uno r3 does not reset when pressing reset button

7
votes

I am starting off with an Arduino Uno and am able to flash some sketches via the Arduino IDE.

Something confuses me though... When I press the reset button on the board I was under the impression that my currently flashed application is removed. That is not the case. It still executes the last flashed application. Is that supposed to happen?

Also when I flash the "bare minimum" sketch with no code instructions, the on board LED on pin 13 is constantly active. Is that the default behavior?

3
arduino

3 Answers

6
votes

All that the reset does is restart your application you wrote in the arduino code IDE.

5
votes

Actually, when you press the reset button, the controller is reset and starts execution at a specified address (the reset vector). In the case of Arduino, the address is in the upper end of the flash memory which contains the boot loader. If the boot loader does not see any traffic in the serial line (i.e. an incoming new program) it transfers execution to your program, i.e. setup(), loop() and the works. The program you load to Arduino is programmed in a flash memory, it does not go away that easily.

2
votes

That button should be labeled REBOOT. That is what it does to the board.

I added this similar answer because I understand that it' conceptually different to re-run the sketch than reset and startup everything