install package for minicom

apt-get install tftpd-hpa minicom

# setup minicom
minicom -s

            +-----[configuration]------+
            | Filenames and paths      |
            | File transfer protocols  |
            | Serial port setup        |
            | Modem and dialing        |
            | Screen and keyboard      |
            | Save setup as dfl        |
            | Save setup as..          |
            | Exit                     |
            | Exit from Minicom        |
            +--------------------------+

select Serial port setup

    +-----------------------------------------------------------------------+
    | A -    Serial Device      : /dev/tty8                                 |
    | B - Lockfile Location     : /var/lock                                 |
    | C -   Callin Program      :                                           |
    | D -  Callout Program      :                                           |
    | E -    Bps/Par/Bits       : 115200 8N1                                |
    | F - Hardware Flow Control : Yes                                       |
    | G - Software Flow Control : No                                        |
    |                                                                       |
    |    Change which setting?                                              |
    +-----------------------------------------------------------------------+
            | Screen and keyboard      |
            | Save setup as dfl        |
            | Save setup as..          |
            | Exit                     |
            | Exit from Minicom        |
            +--------------------------+

serial port
ttyS0 = com1  ,ttyS1 = com2
usbToSerial port --> ttyUSB0
bluetooth --> rfcomm0
modem -->   ttyACM0



    +-----------------------------------------------------------------------+
    | A -    Serial Device      : /dev/ttyUSB0                              |
    | B - Lockfile Location     : /var/lock                                 |
    | C -   Callin Program      :                                           |
    | D -  Callout Program      :                                           |
    | E -    Bps/Par/Bits       : 115200 8N1                                |
    | F - Hardware Flow Control : No                                        |
    | G - Software Flow Control : No                                        |
    |                                                                       |
    |    Change which setting?                                              |
    +-----------------------------------------------------------------------+

if the HardFlowControl is yes , output is working but input is not working.

root@jcjung:~# dmesg | tail -5
[ 4079.056577] usb 1-2: Setting MaxPacketSize 64
[ 4079.064758] usb 1-2: FTDI USB Serial Device converter now attached to ttyUSB0
[ 4079.064794] usbcore: registered new interface driver ftdi_sio
[ 4079.064801] ftdi_sio: v1.5.0:USB FTDI Serial Converters Driver
[ 4079.147752] ftdi_sio ttyUSB0: ftdi_submit_read_urb - failed submitting read urb, error -22

execute minicom