Table 1: POSIX functions will work on the iPAQ as well as they do on the desktop. The most common of these functions for writing to a serial port are shown here
Function |
Parameters |
Description |
| open | char*: serial port name (i.e., "/dev/ttyS0") int: access flags (i.e., O_WRONLY); see bits/fcntl.h |
Opens the serial port and returns a handle to it or -1 on error. |
| close | int: handle to the serial port (obtained by calling open) | Closes the serial port. |
| tcgetattr | int: handle to the serial port struct termios*: structure containing serial port parameters; see bits/termios.h |
Gets the parameters for the serial port and stores them in the given termios structure. |
| tcsetattr | int: handle to the serial port int: specifies when the changes should take effect (almost always TCSANOW); see bits/termios.h struct termios*: structure containing serial port parameters |
Sets the parameters for the serial port. This is typically used to set the baud rate. |
| cfsetospeed | struct termios*: structure containing serial port parameters speed_t: a constant such as B2400, B9600, etc.; see bits/termios.h |
A convenience function to set the output speed of the serial port. The given termios structure must then be set using tcsetattr. |
| write | int: handle to the serial port void*: buffer containing bytes to be written int: number of bytes in the buffer |
Sends the given bytes through the serial port; returns -1 on error. |
