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--- linux:serial_ports [2020/09/30 07:41] – ↷ Page moved and renamed from linux_serial_ports to linux:serial_ports utedass
+++ linux:serial_ports [2022/09/12 00:30] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
+====== Possible alternatives for virtual serial ports ======
+  * Pseudo teletype -- Linux C programming
+  * socat -- Command
+  * fuse -- Filesystem in userspace
+  * <del>named pipes -- Heave data between processes</del> <color #ed1c24>One-way</color>
+^ Method ^ Description ^ Pros ^ Cons ^ Dependencies ^
+| pty    | Virtual terminal device | Full duplex     | Must create links to name them         | native      |
+| socat  | Multipurpose relay      | Super flexible  | External program.\\ Maybe less control | socat       |
+| fuse   | Filesystem in userspace | ??              | ????                                   | libfuse-dev |
+| fifo   | Named pipes             | Simple          | One-way only                           | native      |
+====== Scratchpad ======
+[[https://www.gnu.org/software/libc/manual/pdf/libc.pdf|glibc manual]] -- Innehåller massa bra info!
+[[https://linux.die.net/man/3/termios|termios man page]]
+[[https://linux.die.net/man/4/tty_ioctl|tty_ioctl man page]]
+[[http://kirste.userpage.fu-berlin.de/chemnet/use/info/libc/libc_12.html#SEC237|Seting up terminals]]
+[[https://www.cmrr.umn.edu/~strupp/serial.html|Serial programming guide for posix]]
+<code>
+errno
+termios
+tcgetattr
+cfsetospeed
+cfsetispeed
+tcsetattr
+posix_openpt
+ioctl_tty
+Använd noncanonical input processing mode för att kunna styra RTS och DTR
+termios.h är en grej
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <termios.h>
+#include <unistd.h>
+gör open på porten
+int fd = open (portname, O_RDWR | O_NOCTTY | O_SYNC);
+</code>
 Get info:
@@ Line 15: / Line 66: @@
 # Using screen. Exit with c-a k
 $ screen /dev/ttyS0 115200
+# Read current configuration using stty
+$ stty -a < /dev/ttyS0
+# or
+$ stty -a -F=/dev/ttyS0
+# Set baud rate and hardware flow control using stty
+$ stty -F=/dev/ttyS0 9600 crtscts ixon
 </code>
+[[https://man7.org/linux/man-pages/man2/poll.2.html|Polla för satan!]]
+[[https://man7.org/linux/man-pages/man7/signal.7.html|Läs på om signaler!]]
+====== Serial port basics ======
+{{ :linux:serial.jpg?400|}}
+|DTE | Data terminal equipment (computer/MCU) |
+|DCE | Data circuit-terminating equipment (modem/device) |
+|RTS | Request to send |
+|CTS | Clear to send |
+|DTR | Data terminal ready |
+|DSR | Data set ready |
+{{:linux:db9-pinout.gif?400 |}}
+====== Accessing a serial port ======
+====== Pseudo teletype ======