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Определение устройств > последовательные устройства


"Определение" последовательных устройств (/dev/ttyS*) для данного интерфейса компьютера (а не устройства подключенного к нему).

The serial interfaces (RS-232) is a legacy interface. It has no enumeration process, you have to tell your application which /dev/ttyS* to use (some application do have some auto-detection features, but it's not always reliable).

About serial interfaces

Последовательный порт может иметь физический интерфейс на вашем компьютере:

Или могут быть "встроены" в другое устройства, вроде:

Often, the computer have an internal UART chipset, but not a physical interface : Recent laptops have the DB-9 connector on the docking station only ; Some desktop have 1 connector available, the 2nd requires an optional cable, etc. so what you see IS NOT what you have.

Which /dev/ttyS* ?

Using hal

hal in installed by default in Desktop Environment (both Gnome and Kde), but not on servers.

Take special attention to 'info.product' and 'linux.device_file' lines :

$hal-find-by-capability --capability serial | xargs -n 1 hal-device
udi = '/org/freedesktop/Hal/devices/pcmcia__1__1_serial_platform_1'
  info.capabilities = {'serial'} (string list)
  info.category = 'serial'  (string)
  info.parent = '/org/freedesktop/Hal/devices/pcmcia__1__1'  (string)
  info.product = 'Merlin UMTS Modem'  (string)
  info.udi = '/org/freedesktop/Hal/devices/pcmcia__1__1_serial_platform_1'  (string)
  linux.device_file = '/dev/ttyS1'  (string)
  linux.hotplug_type = 2  (0x2)  (int)
  linux.subsystem = 'tty'  (string)
  linux.sysfs_path = '/sys/class/tty/ttyS1'  (string)
  serial.device = '/dev/ttyS1'  (string)
  serial.originating_device = '/org/freedesktop/Hal/devices/pcmcia__1__1'  (string)
  serial.physical_device = '/org/freedesktop/Hal/devices/pcmcia__1__1'  (string)
  serial.port = 1  (0x1)  (int)
  serial.type = 'platform'  (string)

udi = '/org/freedesktop/Hal/devices/pci_8086_2a07_serial_platform_0'
  info.capabilities = {'serial'} (string list)
  info.category = 'serial'  (string)
  info.parent = '/org/freedesktop/Hal/devices/pci_8086_2a07'  (string)
  info.product = 'Mobile PM965/GM965 KT Controller'  (string)
  info.udi = '/org/freedesktop/Hal/devices/pci_8086_2a07_serial_platform_0'  (string)
  linux.device_file = '/dev/ttyS0'  (string)
  linux.hotplug_type = 2  (0x2)  (int)
  linux.subsystem = 'tty'  (string)
  linux.sysfs_path = '/sys/class/tty/ttyS0'  (string)
  serial.device = '/dev/ttyS0'  (string)
  serial.originating_device = '/org/freedesktop/Hal/devices/pci_8086_2a07'  (string)
  serial.physical_device = '/org/freedesktop/Hal/devices/pci_8086_2a07'  (string)
  serial.port = 0  (0x0)  (int)
  serial.type = 'platform'  (string)

more example : HowToIdentifyADevice/Serial/thinkpad-a22-hal.txt ; HowToIdentifyADevice/Serial/usb-to-serial-adapter_hal.txt

Find in /sys/*

This command should work on all standard Debian installation (even minimalist ones).

$find /sys/ -name 'tty:ttyS*'
/sys/devices/pci0000:00/0000:00:1e.0/0000:15:00.0/0.0/tty:ttyS1
/sys/devices/pci0000:00/0000:00:03.3/tty:ttyS0
/sys/devices/platform/serial8250/tty:ttyS3
/sys/devices/platform/serial8250/tty:ttyS2
/sys/devices/pci0000:00/0000:00:1a.1/usb4/4-1/4-1:1.0/ttyUSB0/tty:ttyUSB0

$lspci 
[..]
00:03.3 Serial controller: Intel Corporation Mobile PM965/GM965 KT Controller (rev 0c)
[..]
00:1a.0 USB Controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Contoller #4 (rev 03)
[..]
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev f3)
[..]
15:00.0 CardBus bridge: Ricoh Co Ltd RL5c476 II (rev ba)

some explanations on this example :

serial8250
ttyS* under "serial8250" probably doesn't exist (they are present by default because it's hard to detect if they are present or not)
0000:00:1e.0/0000:15:00.0/0.0/tty:ttyS1

if you look at the lspci output above, pci device "00:1e.0" is a PCI bridge to the card bus controller ("15:00.0"), so ttyS1 is a PC Card device.

pci0000:00/0000:00:03.3/tty:ttyS0
ttyS0 is directly connected to the PCI bus. according to the PCI device name, you can assume it isn't a Modem, so it's probably a built-in serial interface.
ttyUSB0/tty:ttyUSB0

if you look at the lspci output above, pci device "00:1a.0" is a USB Controller, so ttyUSB1 is a USB device (USB-to-serial or modem).

more example : HowToIdentifyADevice/Serial/thinkpad-a22-find-sysfs.txt


keywords:UART ; 8250 , 16550 ; 16450 ; RS232 ; RS-232 ; DB-9 ; DB9 ; DB25 ; UART ; Serial ; ttyS0 ; ttyS1 ; ttyS3 ; ttyS4 ;COM1 ; COM2 ; Com Port