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linux_serial_programming [2019/03/31 14:49] (current) |
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| + | ====== Linux Serial Programming ====== | ||
| + | |||
| + | There is ''%%termios%%'' which is the linux library of accessing the serial port. It is super | ||
| + | fucking complicated. | ||
| + | |||
| + | There are some concepts to keep in mind. | ||
| + | |||
| + | **1. Canonical mode**: This is most useful when dealing with real terminals, or devices that provide line-by-line | ||
| + | communication. The terminal driver returns data line-by-line. | ||
| + | |||
| + | **2. Non-canonical mode:** In this mode, no special processing is done, and the terminal driver returns individual characters. | ||
| + | |||
| + | **3. "Blocking"**: sets whether a read() on the port waits for the specified number of | ||
| + | characters to arrive. Setting no blocking means that a read() returns however many | ||
| + | characters are available without waiting for more, up to the buffer limit. | ||
| + | |||
| + | The man page ([[http://man7.org/linux/man-pages/man3/termios.3.html|link]]) for | ||
| + | ''%%termios%%'' is actually pretty useful. This is not that complicated. I, and you, can | ||
| + | friggin do this. | ||
| + | |||
| + | There is an interesting function called ''%%cfmakeraw%%'' that sets the terminal to what I | ||
| + | want I think I want. | ||
| + | |||
| + | ===== General Programming Serial Stuff ===== | ||
| + | |||
| + | If you use ''%%printf%%'' to print to the terminal be aware that ''%%stdout%%'' is buffered! That | ||
| + | means that it doesn't just instantaneously print to the terminal. It either waits for | ||
| + | a new line, has a timeout (i think) or a buffer fills up. | ||
| + | |||
| + | To get ''%%printf%%'' to print immediately either call ''%%fflush(stdout)%%'' or do the following to | ||
| + | make the buffer size smaller: | ||
| + | |||
| + | <code c> | ||
| + | // printf which uses stdout is buffered. The larger the buffer, the slower it | ||
| + | // will post to the terminal. I can either set the buffer to smaller size like | ||
| + | // the following, or call fflush(stdout) to force a write to the terminal | ||
| + | char buffer[10]; | ||
| + | setvbuf(stdout, buffer, _IOFBF, sizeof(buffer)); | ||
| + | </code> | ||
| + | |||
| + | ===== General OS Serial Stuff ===== | ||
| + | To list the USB devices by dev path use this script ([[http://unix.stackexchange.com/questions/144029/command-to-determine-ports-of-a-device-like-dev-ttyusb0|link]]). | ||
| + | |||
| + | I have added this script to ''%%paul_scripts%%'' and added an alias called ''%%listusb%%'' to my ''%%.zshrc%%'' file. | ||