Arduino digital pin testing with serial monitor

I have a Arduino nano board for 2 year which I use for multiple programming and testing with it but suddenly some pins start to respond with errors, I have used multimeter to check the defected pin which is a time taking and little hassle work where the pins can be shorted, so I search for a program which do the work with out attach any other to the board other then power supply / u.s.b connection. but I have not found any program for the work so I have made the program which will help me to find the error in the pin port with ease by using serial monitor. it can be used for arduino uno, nano micro, mega. (i worked on uno and nano for micro and mega I have done a simulation in proteus which work).

and there is online simulation in tinkercad https://www.tinkercad.com/things/cYxvuxLfxH8

here you can check.

note:-

• for the better results please connect to usb as we use serial monitor (no damaged usb wire).

• this program useful only to find error pin in digital port pins as the pin represent by numbers but for analog pin they are combined of letter A and numbers.

• this program work by making all digital pins as input state where it tells the pin is in high or low.

• other then some pins like 0, 1 and 12 all other pins shows low state. if the pin shows different value then we have a error pin or some thing is connected to it.

• please check the schematic and pin layout of the board as some pins as by default either high or low.