thank you very much for the idea of testing the usb meshing. Now, I found that the meshing between male and female connectors are fine.. so I am not sure now what is the source of my problem.
I will tell more details . yes I am using USB host shield for arduino. I used the arduino example "testusbhostFAT" for around 1 year and it works great with my arduino + usb shield. I took the code and I made some modifications to suit my interest, and it also worked fine with me. but somedays ago, when I was trying the arduino and the shield in some circuit, I noticed that my code does not behave as usual. I began to suspect my code, so I uploaded again the original testusbhostFAT, and I found the same weird performance (really I do not know what changed!)
in the past, the arduino showed me messages related to opening a file named "message.txt" that exist in usb stick, and creating another file in the usb stick named "Hello.txt". but now this does not happen. currently, this is what I get on serial monitor:
Start
Current UsbDEBUGlvl 81
'+' and '-' increase/decrease by 0x01
'.' and ',' increase/decrease by 0x10
't' will run a 10MB write/read test and print out the time it took.
'e' will toggle vbus off for a few moments.
Long filename support: Enabled
Total EXT RAM banks 0
Available heap: 7124 Bytes
SP 21ef
Available heap: 7097 Bytes
VBUS on
USB state = 20
USB state = 40
USB state = 50
USB state = 51
USB state = 90
Available heap: 6650 Bytes
Available heap: 6650 Bytes
Available heap: 6650 Bytes
Available heap: 6650 Bytes
Available heap: 6650 Bytes
Available heap: 6650 Bytes
and it keeps showing more and more without showing anything from the usb stick!
I suspected that my usb stick is defective, and i replaced it, but the result is the same.
regarding what you mentioned about enumeration, I do not know, but I am testing the same shield with the same usb stick, it is still possible that enumeration is the cause?
does the above mentioned behavior means that my shield became defective for some reason and I need to replace it totally?