[arch-general] Connection through USB to TTL Serial Cable

Csányi Pál csanyipal at gmail.com
Thu May 21 11:33:03 UTC 2015

2015-05-21 4:13 GMT+02:00 Sean Greenslade <sean at seangreenslade.com>:
> On Wed, May 20, 2015 at 09:41:13PM +0200, Csányi Pál wrote:
>> I tried these commands:
>> $ cu -s 115200 -l /dev/ttyS0
>> cu: /dev/ttyS0: Line in use
>> $ cu -s 115200 -l /dev/ttyS1 # ( also S2, S3 )
>> Connected.
>> cu: Got hangup signal
>> Disconnected.
>> dmesg gives me no ifnormation about such device:
>> [36829.865727] Shorewall:net-fw:DROP:IN=enp0s20 OUT=
>> MAC=00:1a:92:ce:61:70:00:22:02:00:07:3d:08:00 SRC=
>> DST= LEN=35 TOS=0x00 PREC=0x00 TTL=48 ID=30265 DF
>> PROTO=UDP SPT=50434 DPT=5093 LEN=15
>> [38367.939572] usb 2-6: new full-speed USB device number 6 using ohci-pci
>> Maybe the Shorewall firewall is the culprit in this case?
> I can almost guarantee you that your firewall has nothing to do with it.
> It is just conincidence that the previous kernel message was from the
> firewall.
> The issue as I see it is that the serial driver kernel module seems to
> not be loading. Are you running any sort of modified / alternative
> kernel? Can you post the results of "uname -a" for us?

I'm running not a modified / alternative kernel.
# uname -a
Linux archcsp 4.0.4-1-ARCH #1 SMP PREEMPT Mon May 18 06:43:19 CEST
2015 x86_64 GNU/Linux

> Also, a "sudo lsusb -v" might be helpful as well.

# lsusb -v
Bus 002 Device 004: ID 0403:6001 Future Technology Devices
International, Ltd FT232 USB-Serial (UART) IC
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0
  bDeviceSubClass         0
  bDeviceProtocol         0
  bMaxPacketSize0         8
  idVendor           0x0403 Future Technology Devices International, Ltd
  idProduct          0x6001 FT232 USB-Serial (UART) IC
  bcdDevice            6.00
  iManufacturer           1 FTDI
  iProduct                2 TTL232RG-VREG3V3
  iSerial                 3 FTWUHYHB
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           32
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              500mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass    255 Vendor Specific Subclass
      bInterfaceProtocol    255 Vendor Specific Protocol
      iInterface              2 TTL232RG-VREG3V3
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x02  EP 2 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               0
can't get device qualifier: Resource temporarily unavailable
can't get debug descriptor: Resource temporarily unavailable
Device Status:     0x0000
  (Bus Powered)

Also I must add that that I have not solded the RX, TX and GND to my
Bubba 2 headless power pc box yet, I'm just testing this FTDI cable; a
very simple test: to contact the TX and the RX wires together on the
cable, to open a console and see if sent characters echo back. ( One
can see more about this here:
forum.mybubba.org/viewtopic.php?f=9&t=2658 )

$ groups
wheel uucp vboxusers csp

where 'csp' is the username.

I shall investigate the provided links in this thread to day later, to
see which kernel module is needed for this FTDI chip.

Regards from Pal

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