after update software on my arduino Nano board via ICSP i can't use USB for serial monitor and update software, why?

  • Update the software that runs on the PC? Update the Arduino boot loader? Update some driver or library you are using? Or, did you just reprogram the Atmel processor directly and erased the Arduino boot loader? – st2000 May 23 '17 at 15:16
  • If you did the last, you no longer have an Arduino. You just have an Atmel processor with some hardware around it. – st2000 May 23 '17 at 15:17
  • As stated, it is very difficult for someone to answer this question. Could you clarify what you have uploaded through ICSP? Mentioning the avrdude command line would already be better (we want to see if you changed fuses, for instances). Showing the output of avrdude might help as well. Also what program did you upload? – jfpoilpret May 23 '17 at 19:45

Assuming you have reprogrammed the Arduino Nano's Atmel processor (an ATmega328) directly using the processor's ICSP pins, you may have erased the Arduino boot loader from the processor. In such a case you no longer have an Arduino. Rather you have an ATmega328 processor surrounded by some hardware.

To recover you need to reprogram the ATmega328 processor with the Arduino boot loader.

  • I'd agree... Bootloader has been overwritten by your 'update'.. – whispers May 23 '17 at 22:12
  • Not "may" - but "have" - because the ATmega family ISP only supports full chip erase, the only way there is still a bootloader in there is if the ISP operation did no erasing, or if the ISP process happened to re-write a functional bootloader in the proper place alongside any application program it wrote. – Chris Stratton May 24 '17 at 5:14

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