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Serial port on my KUBUNTU doesn't seem to be working. This is the first time I am trying to use serial port on Linux so I might be doing something ...
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  1. #1
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    Unhappy serial port problem on Kubuntu 9.04 x86-64 bit


    Serial port on my KUBUNTU doesn't seem to be working. This is the first time I am trying to use serial port on Linux so I might be doing something stupid.

    I have attached a loop-back on my serial port to check if data is actually transmitted and received. From looking at /proc/tty/driver/serial it looks like data is being transmitted but nothing is being recieved, however voltmeter doesn't show any fluctuation when data is being transmitted so I doubt if any data is 'actually' being transmitted.

    Here are the results of dmesg, setserial, stty, etc

    dmesg | grep tty:
    [ 0.010000] console [tty0] enabled
    [ 1.551851] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
    [ 1.552105] 00:0c: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A

    ls -l /dev/ttyS*:
    crw-rw-rw- 1 sanket dialout 4, 64 2009-05-13 13:17 /dev/ttyS0
    crw-rw---- 1 root dialout 4, 65 2009-05-13 11:38 /dev/ttyS1
    crw-rw---- 1 root dialout 4, 66 2009-05-13 11:38 /dev/ttyS2
    crw-rw---- 1 root dialout 4, 67 2009-05-13 11:38 /dev/ttyS3

    stty -F /dev/ttyS0 -a:
    speed 9600 baud; rows 0; columns 0; line = 0;
    intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>; eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R;
    werase = ^W; lnext = ^V; flush = ^O; min = 1; time = 0;
    -parenb -parodd cs8 hupcl -cstopb cread clocal -crtscts
    -ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl ixon -ixoff -iuclc -ixany -imaxbel -iutf8
    opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
    isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt echoctl echoke

    setserial /dev/ttyS0:
    /dev/ttyS0, Line 0, UART: 16550A, Port: 0x03f8, IRQ: 4
    Baud_base: 9600, close_delay: 50, divisor: 0
    closing_wait: 3000
    Flags: spd_normal auto_irq

    lspnp -v:
    00:0c PNP0501 16550A-compatible serial port
    state = active
    io 0x3f8-0x3ff
    irq 4
    dma disabled

    lspci:
    .
    .
    00:01.0 ISA bridge: nVidia Corporation MCP78S [GeForce 8200] LPC Bridge (rev a2)
    .
    .

    vim /proc/tty/driver/serial:
    serinfo:1.0 driver revision:
    0: uart:16550A port:000003F8 irq:4 tx:67963 rx:0
    1: uart:unknown port:000002F8 irq:3
    2: uart:unknown port:000003E8 irq:4
    3: uart:unknown port:000002E8 irq:3

    As you can see this shows transmitted data but recieved data is 0, which cant be the case as all the data transmitted should be recieved due to loopback.

    I have checked BIOS and it shows serial port on IRQ 4 and address 0x3F8.
    I am transmitting data using echo test_message > /dev/ttyS0, cp filename /dev/ttyS0 and by using minicom, cutecom.

    I am trying to recieve data using tail -f /dev/ttyS0, cat /dev/ttyS0 and using cutecom application.
    I have wasted two days with this without any progress.
    Please help.

    thanks.

  2. #2
    Just Joined!
    Join Date
    May 2009
    Posts
    1
    Have the same problem

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