include headers
add project comment
unlock FLASH
add function to send string via USB line
delete unused variables and declare the related variables for ymodem and stmflash
change ttyACMx when the port is busy
change string sending code
NA
test string send
add USB_VCP_TxChar()
change into pointer
change into char
add USB_VCP_RxChar() function
delete USB_VCP_RxChar() function
use circular array to store rx data and adding related variables
test for USB_VCP_RxData()
determine if rx data exisit
NA
delete unused timer3 part
delete timer3 related part