Arduino resetting while reconnecting the serial. When you connect to the serial port. Your host sending a DTR signal is what's causing the Arduino to reset. May 04, 2013 Disabling auto reset on the Arduino Due. This would erase the flash upon every opening of the serial port! So this erase+reset sequence is only done. Well it depends on your software logic. Lets say you are controlling your arduino from smartphone via wifi/bluetooth. You send a command from your phone to change (lets say) the wifi ssid or password it is connecting to. You get that command in arduino, store the new ssid/password in eeprom or sd card and RESET your arduino.

February 26, 2016 Everyone that uses Arduino can tell you how easy it is to get projects going once they have an Arduino board in hand. Just load up the blink code and press upload. In a matter of seconds, your Arduino LED is blinking ever so confidently. Bionaire Bwf0910ar-wcu Manual on this page. But do you stop and wonder how Arduino receives the blink code? Enter Arduino bootloader.

Every Arduino has a bootloader, a small program that is always stored on the Arduino to update the code in the Arduino. It only runs once per reset. It looks for new code to be loaded to the Arduino before starting the existing code. The bootloader works like this: On the PC side, to trigger a reset on the RESET pin, the PC (avrdude.exe or GNU/Linux equivalent) opens the serial port to Arduino when your press upload and the code is ready to upload. This causes the Data Transmit Ready (DTR) line of the USB/TTL chip to go LOW. The Arduino board has a capacitor charging circuit that uses this LOW (charging the capacitor) signal to momentarily pull down the RESET line of the ATMEGA328P chip before returning it to HIGH (capacitor charging completes). So Arduino resets each time its serial port is opened.

Upon reset, Arduino enters the bootloader. The bootloader looks at the source that caused the reset. There are several sources that can cause a reset. If the reset was caused by the RESET pin, then it waits for one second for the PC to send in commands. When it receives valid commands, it will start accepting new Arduino code in HEX format and erase the existing code to load new one.