Difference between revisions of "How to use TTY with User Terminal"

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1 Purpose[edit]

This article describes how to use TTY with a user terminal. The TTY overview is described in Serial TTY overview article.

The use case of the following examples is a data transfer between a STM32 MPU board and PC, over a USB to a RS232 adapter cable.
The setup of this use case is described in details in the How to get Terminal article.


For the following examples:

  • uart4 is activated by default (for the Linux console)
  • usart3 is enabled by device tree
  • The usart3 pins are connected to a RS232 card
  • The RS232 card is connected to the PC over the USB to RS232 adapter cable.

Note: Some TTY tools are used in this article. A list of TTY tools is defined a dedicated article [TTY Tools ].

2 Print the file name of the terminal connected to standard input (with tty tool)[edit]

Board $> tty
# The console is connected to uart4 (aka ttySTM0) #
/dev/ttySTM0

3 Change serial port configuration (with stty tool)[edit]

Many serial port properties can be displayed and changed with the stty tool. The full feature list is available in stty user manual pages [1] .

Board $> stty --help
  • Display the current configuration:
Board $> stty -a -F /dev/ttySTM1
# Display the configuration of uart3 (aka ttySTM1) #
speed 115200 baud; rows 45; columns 169; line = 0;
  • Display only the current baud rate:
Board $> stty -F /dev/ttySTM1 speed
# uart3 (aka ttySTM1) baud rate is set to 115200 bps #
115200
  • Change the baud rate:

stty -F /dev/ttySTMx EXPECTED_BAUDRATE

Example: change the baud rate to 19200

# Change uart3 (aka ttySTM1) baud rate to 19200 bps #
Board $> stty -F /dev/ttySTM1 19200

The stty tool proposes many arguments allowing many operations on a tty terminal, such as:

  • special settings (various arguments such as speed, line discipline, minimum number of characters for a completed read, size, timeout, etc...)
  • control settings
  • input settings
  • output settings
  • local settings
  • combination settings


Note: If you want to go further, an interesting tutorial describes termios and stty [2].

4 Send / Receive data (with stty, minicom, echo and cat tools)[edit]

4.1 Default configuration (8 data bits frame, no parity errors detection, no framing errors detection)[edit]

Sending data can be simply done by opening the device as a file and writing data to it.

  • Configure a port on ttySTM1 (aka usart3)
Board $> stty -F /dev/ttySTM1 115200 -echo
  • Display the current configuration on ttySTM1 (usart3):
# display the configuration of uart3 (aka ttySTM1) #
Board $> stty -a -F /dev/ttySTM1
speed 115200 baud; rows 45; columns 169; line = 0;
  • Open a port on ttySTM1 (usart3) to receive data
Board $> cat /dev/ttySTM1 &
  • On the remote PC, identify the tty terminal associated to RS232 card connected on STM32MPU USART3 pins
# Command to execute from host terminal #
PC $> ls /dev/ttyUSB*

/dev/ttyUSB0

  • Open a minicom in a second terminal on the remote device connected on USART3 pins
PC $> minicom -D /dev/ttyUSB0
  • Display the current configuration on ttyUSB0 (remote device):
# Display the configuration of host uart (aka ttyUSB0) #
PC $> stty -a -F /dev/ttyUSB0
speed 115200 baud; rows 45; columns 169; line = 0;
  • Send data from remote PC to STM32MPU over USART3 with default termios configuration (8 frames length, no parity)
# Execute this command from host terminal #
PC $> echo "HELLO" > /dev/ttyUSB0
  • send data from STM32MPU to remote PC over USART3 with default termios configuration (8 frames length, no parity)
# Execute this command from STM32 terminal #
Board $> echo "HELLO" > /dev/ttySTM1

4.2 Parity errors detection[edit]

Some additional termios funtions allow to enable parity errors detection:

  • parenb: Parity enable
  • parodd: Odd parity else even
  • inpck: Enable input parity or framing check
  • ignpar: Ignore characters with parity or framing errors


Exemples:

  • Configure a port on ttySTM1 (usart3) with even parity enabling
# STM32 parity enabling #
Board $> stty -F /dev/ttySTM1 115200 -echo parenb -parodd inpck ignpar
  • Open a port on ttySTM1 (usart3) to receive data
Board $> cat /dev/ttySTM1 &
Open a minicom in a second terminal on the remote device connected on USART3 pins
PC $> minicom -D /dev/ttyUSB0
  • Configure a port on ttyUSB0 (remote device) with even parity enabling:
# Remote device parity enabling #
PC $> stty -a -F /dev/ttyUSB0 115200 -echo parenb -parodd inpck ignpar
speed 115200 baud; rows 45; columns 169; line = 0;
  • Send data from remote PC to STM32MPU over USART3 with default termios configuration (8 frames length, no parity)
# Execute this command from host terminal #
PC $> echo "HELLO" > /dev/ttyUSB0
  • send data from STM32MPU to remote PC over USART3 with default termios configuration (8 frames length, no parity)
#  Execute this command from STM32 terminal #
Board $> echo "HELLO" > /dev/ttySTM1


4.3 Framing errors detection[edit]

Some additional termios funtions allow to enable framing errors detection:


Exemples:

  • Configure a port on ttySTM1 (usart3) with framing check enabling and 7 data bits length frames
# STM32 framing enabling #
Board $> stty -F /dev/ttySTM1 115200 -echo cs7 inpck ignpar
  • Open a port on ttySTM1 (usart3) to receive data
Board $> cat /dev/ttySTM1 &
Open a minicom in a second terminal on the remote device connected on USART3 pins
PC $> minicom -D /dev/ttyUSB0
  • Configure a port on ttyUSB0 (remote device) with framing check enabling and 7 data bits length frames
# Remote device parity enabling #
PC $> stty -a -F /dev/ttyUSB0 115200 -echo cs7 inpck ignpar
speed 115200 baud; rows 45; columns 169; line = 0;
  • Send data from remote PC to STM32MPU over USART3 with default termios configuration (8 frames length, no parity)
# Execute this command from host terminal #
PC $> echo "HELLO" > /dev/ttyUSB0
  • send data from STM32MPU to remote PC over USART3 with default termios configuration (8 frames length, no parity)
# Execute this command from STM32 terminal #
Board $> echo "HELLO" > /dev/ttySTM1

5 Identify processes using a tty serial device (with fuser tool)[edit]

Board $> fuser /dev/ttySTM0
# The process numbered 395, 691 and 3872 are using a tty serial device #
395 691 3872

6 Link a tty serial device with a line discipline (with ldattach tool)[edit]

Attach ttySTM1 with line discipline number n :

Board $> ldattach n /dev/ttySTM1

7 File transfer over serial console[edit]

Please see the dedicated article How to transfer a file over serial console.

8 References[edit]

<noinclude>

{{ArticleMainWriter | ErwanLR}}
{{ArticleApprovedVersion | ErwanLR | FabriceG (Passed), AlexandreT (Passed) , NathalieS | No previous approved version | AlainF - 14Aug'18 - 8369 | 28Aug'18}}
{{UpdateNeededForNewRelease}}

[[Category:Serial TTY|3]]</noinclude>

__TOC__<br />


==Purpose==
This article describes how to use TTY with a user terminal. The TTY overview is described in [[Serial TTY overview]] article. <br/>


The use case of the following examples is a data transfer between a STM32 MPU board and PC, over a USB to a RS232 adapter cable. <br/>

The setup of this use case is described in details in the [[How_to_get_Terminal#Remote Terminal via serial link (UART/USB)|How to get Terminal]] article.

For the following examples:

* uart4 is activated by default (for the Linux console)
* usart3 is enabled by [[Serial TTY_device_tree_configuration#Activation_of_a_USART_or_UART_instance|device tree]]
* The usart3 pins are connected to a RS232 card
* The RS232 card is connected to the PC over the USB to RS232 adapter cable.

Note: Some TTY tools are used in this article. A list of TTY tools is defined a dedicated article [TTY Tools ].

== Print the file name of the terminal connected to standard input (with tty tool)==
 {{Board$}} tty
 {{highlight|# The console is connected to uart4 (aka ttySTM0) #}}
 {{Green|'''/dev/ttySTM0'''}}

==Change serial port configuration (with stty tool)==
Many serial port properties can be displayed and changed with the stty tool. The full feature list is available in stty user manual pages <ref>[https://linux.die.net/man/1/stty stty manual page]</ref> .
 {{Board$}} stty --help

* Display the current configuration:
 {{Board$}} stty -a -F /dev/ttySTM1
 {{highlight|# Display the configuration of uart3 (aka ttySTM1) #}}
 speed 115200 baud; rows 45; columns 169; line = 0;

* Display only the current baud rate:
 {{Board$}} stty -F /dev/ttySTM1 speed
 {{highlight|# uart3 (aka ttySTM1) baud rate is set to 115200 bps #}}
 115200

* Change the baud rate: 
stty -F /dev/ttySTMx ''EXPECTED_BAUDRATE''<br/>
<br/>

Example: change the baud rate to 19200
 {{highlight|# Change uart3 (aka ttySTM1) baud rate to 19200 bps #}}
 {{Board$}} stty -F /dev/ttySTM1 19200

The stty tool proposes many arguments allowing many operations on a tty terminal, such as: 
* special settings (various arguments such as speed, line discipline, minimum number of characters for a completed read, size, timeout, etc...)
* control settings
* input settings
* output settings
* local settings
* combination settings
<br/>

'''Note''': If you want to go further, an interesting tutorial describes termios and stty <ref>[https://blog.nelhage.com/2009/12/a-brief-introduction-to-termios-termios3-and-stty/ A Brief Introduction to termios: termios(3) and stty] stty tutorial</ref>.

==Send / Receive data (with stty, minicom, echo and cat tools)==

===Default configuration (8 data bits frame, no parity errors detection, no framing errors detection)===
Sending data can be simply done by opening the device as a file and writing data to it.<br/>

* Configure a port on ttySTM1 (aka usart3)
 {{Board$}} stty -F /dev/ttySTM1 115200 -echo

* Display the current configuration on ttySTM1 (usart3):
 {{highlight|# display the configuration of uart3 (aka ttySTM1) #}}
 {{Board$}} stty -a -F /dev/ttySTM1
 speed 115200 baud; rows 45; columns 169; line = 0;

* Open a port on ttySTM1 (usart3) to receive data
 {{Board$}} cat /dev/ttySTM1 &

* On the remote PC, identify the tty terminal associated to RS232 card connected on STM32MPU USART3 pins
 {{highlight|# Command to execute from host terminal #}}
 {{PC$}} ls /dev/ttyUSB*
/dev/ttyUSB0

* Open a minicom in a second terminal on the remote device connected on USART3 pins
 {{PC$}} minicom -D /dev/ttyUSB0

* Display the current configuration on ttyUSB0 (remote device):
 {{highlight|# Display the configuration of host uart (aka ttyUSB0) #}}
 {{PC$}} stty -a -F /dev/ttyUSB0
 speed 115200 baud; rows 45; columns 169; line = 0;

* Send data from remote PC to STM32MPU over USART3 with default termios configuration (8 frames length, no parity)
 {{highlight|# Execute this command from host terminal #}}
 {{PC$}} echo "HELLO" > /dev/ttyUSB0

* send data from STM32MPU to remote PC over USART3  with default termios configuration (8 frames length, no parity)
 {{highlight|# Execute this command from STM32 terminal #}}
 {{Board$}} echo "HELLO" > /dev/ttySTM1

===Parity errors detection===
Some additional termios funtions allow to enable parity errors detection:
* parenb: Parity enable
* parodd: Odd parity else even
* inpck: Enable input parity or framing check
* ignpar: Ignore characters with parity or framing errors<br/>

Exemples:
* Configure a port on ttySTM1 (usart3) with even parity enabling
 {{highlight|# STM32 parity enabling #}}
 {{Board$}} stty -F /dev/ttySTM1 115200 -echo parenb -parodd inpck ignpar

* Open a port on ttySTM1 (usart3) to receive data
 {{Board$}} cat /dev/ttySTM1 &

 Open a minicom in a second terminal on the remote device connected on USART3 pins
 {{PC$}} minicom -D /dev/ttyUSB0

* Configure a port on ttyUSB0 (remote device) with even parity enabling:
 {{highlight|# Remote device parity enabling #}}
 {{PC$}} stty -a -F /dev/ttyUSB0 115200 -echo parenb -parodd inpck ignpar
 speed 115200 baud; rows 45; columns 169; line = 0;

* Send data from remote PC to STM32MPU over USART3 with default termios configuration (8 frames length, no parity)
 {{highlight|# Execute this command from host terminal #}}
 {{PC$}} echo "HELLO" > /dev/ttyUSB0

* send data from STM32MPU to remote PC over USART3  with default termios configuration (8 frames length, no parity)
 {{highlight|#  Execute this command from STM32 terminal #}}
 {{Board$}} echo "HELLO" > /dev/ttySTM1<br/>


===Framing errors detection===
Some additional termios funtions allow to enable framing errors detection:
* csize: Number of bits per byte (CS5, CS6, CS7, or CS8[[Serial_TTY_overview#CSIZE_configurations|character size and parity bit configurations]])
* inpck: Enable input framing check
* ignpar: Ignore characters with parity or framing errors<br/>

Exemples:
* Configure a port on ttySTM1 (usart3) with framing check enabling and 7 data bits length frames
 {{highlight|# STM32 framing enabling #}}
 {{Board$}} stty -F /dev/ttySTM1 115200 -echo cs7 inpck ignpar

* Open a port on ttySTM1 (usart3) to receive data
 {{Board$}} cat /dev/ttySTM1 &

 Open a minicom in a second terminal on the remote device connected on USART3 pins
 {{PC$}} minicom -D /dev/ttyUSB0

* Configure a port on ttyUSB0 (remote device) with framing check enabling and 7 data bits length frames
 {{highlight|# Remote device parity enabling #}}
 {{PC$}} stty -a -F /dev/ttyUSB0 115200 -echo cs7 inpck ignpar
 speed 115200 baud; rows 45; columns 169; line = 0;

* Send data from remote PC to STM32MPU over USART3 with default termios configuration (8 frames length, no parity)
 {{highlight|# Execute this command from host terminal #}}
 {{PC$}} echo "HELLO" > /dev/ttyUSB0

* send data from STM32MPU to remote PC over USART3  with default termios configuration (8 frames length, no parity)
 {{highlight|# Execute this command from STM32 terminal #}}
 {{Board$}} echo "HELLO" > /dev/ttySTM1

==Identify processes using a tty serial device (with fuser tool)==
 {{Board$}} fuser /dev/ttySTM0
 {{highlight|# The process numbered 395, 691 and 3872 are using a tty serial device #}}
 395 691 3872

==Link a tty serial device with a line discipline (with ldattach tool)==

Attach ttySTM1 with [[Serial TTY line discipline|line discipline]] number ''n'' :
 {{Board$}} ldattach ''n'' /dev/ttySTM1

==File transfer over serial console==
Please see the dedicated article [[How to transfer a file over serial console]].

==References==<references />
Line 133: Line 133:
 
===Framing errors detection===
 
===Framing errors detection===
 
Some additional termios funtions allow to enable framing errors detection:
 
Some additional termios funtions allow to enable framing errors detection:
* csize: Number of bits per byte (CS5, CS6, CS7, or CS8)
+
* csize: Number of bits per byte ([[Serial_TTY_overview#CSIZE_configurations|character size and parity bit configurations]])
 
* inpck: Enable input framing check
 
* inpck: Enable input framing check
 
* ignpar: Ignore characters with parity or framing errors
 
* ignpar: Ignore characters with parity or framing errors