This project is about uploading code to ARDUINO NANO using a HC-05 Bluetooth module
The program data is send over Bluetooth HC-05 , whenever there is data available the state pin of HC-05 goes LOW. at that moment the Arduino's reset pin also has to be LOW for a short period of time so that the Arduino can go into programming mode.
115200 is for Arduino Nano with new bootloader for old bootloaders change it to 57600
if AT+INIT gives any error ignore it as it means the command has already been executed
the name of the Bluetooth can be changed also for better reference using,
after each AT command the hc-05 should return OK
generating a single pulse
As the Arduino Nano requires a high-low-high pulse to go into programming mode, A circuit is needed to provide that pulse at the correct time.
the NOT gates and the R-C circuit is used to add a delay before the signal is passed to the next NOT gate.
When input is 5v the output of XNOR will be 5v. the moment the input changes to 0v one input of XNOR will receive 0v but because of the delay the other input pin will be at 5v momentarily which makes the output of the XNOR gate to 0v. After some moment both the input pins are 0v so the output becomes 5v again.
This creates the short pulse that is needed for the Arduino Nano to reset.