Arduino NANO

Hi my name is Dave and need help. I have successfully built a PIR Security light using a Arduino NANO board with the Atmega328 chipset and all working.

Ihave built up another board as a spare and again all working.

I have 2 more spare boards which dont appear to be working even though they are regognised by Windows 7 when you plug them in.

I have done the loop back test exactly as per the instructions on this site and I am unable to to recieve anything back that I have typed on the screen after sending or pressing the enter key.

I can still load the PIR Sketch but it does not work at all.

I can load the Blink Test code which is embedded in the Arduino Software and believe it or not the LED which is connected to pin13 actually flashes and I can alter the flash rate faster by altering the code to 500 instead of 1000 so that part of the board is working.

Has anyone any idea as to what could be the problem with my 2 faulty boards.

Regards to all Dave G4RVH

Hi, welcome to the forum.

When they are fake/clone/copy boards from Ebay, they could have the CH340G usb-serial chip which needs a special driver, or they could have the counterfeit FTDI usb-serial chip, or the bootloader can be bad.
Some cheap boards are actually wrong designed, so the pcb is faulty.

Could you make of photo of them, that shows both sides ?

A PIR sensor could have a open collector ouput. Perhaps it helps if you turn on the pullup resistor. For example if pin 2 is used: pinMode ( 2 , INPUT_PULLUP ) ;

The fact that you can load the blink sketch with different blink times makes me think that the drivers are OK.

That said, did all the nanos come from the same source? If so post a link to where they came from otherwise post links to where they all came from.

This one has indeed the CH340G usb-serial chip :

This is the driver : CH341SER.EXE - 南京沁恒微电子股份有限公司

I assume you have already installed the driver.
It hard to say from here what can be wrong with board. Testing every pin for output and input will take some time.
Can you check the board with a magnifier ? Look for solder splats that cause shortcuts, or bad soldering.