Parapin 1.0.0 review
DownloadParapin library makes it easy to write C code under Linux that controls individual pins on a PC parallel port
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Parapin library makes it easy to write C code under Linux that controls individual pins on a PC parallel port.
This kind of control is very useful for electronics projects that use the PC's parallel port as a generic digital I/O interface.
Parapin goes to great lengths to insulate the programmer from the somewhat complex parallel port programming interface provided by the PC hardware, making it easy to use the parallel port for digital I/O. By the same token, this abstraction also makes Parapin less useful in applications that need to actually use the parallel port as a parallel port (e.g., for talking to a printer).
Parapin has two ``personalities'': it can either be used as a user-space C library, or linked as part of a Linux kernel module.
There is also a device driver that provides access to the kernel module from user-space, allowing the administrator to use filesystem permissions to control access to the port.
Parapin was written with efficiency in mind, so that Parapin can be used in time-sensitive applications.
Using Parapin should be very nearly as fast as writing directly to the parallel port registers manually.
Parapin provides a simple interface that lets programs use pins of the PC parallel port as digital inputs or outputs. Using this interface, it is easy to assert high or low TTL logic values on output pins or poll the state of input pins.
Some pins are bidirectional--that is, they can be switched between input and output modes on the fly.
Parapin was originally written by Jeremy Elson while at the University of Southern California's Information Sciences Institute. The original work was supported by DARPA under grant No. DABT63-99-1-0011 as part of the SCADDS project, and was also made possible in part due to support from Cisco Systems. It is freely available under the GNU Library Public License (LGPL).
Current maintenance of Parapin is coordinated by Al Hooton, who also wrote the device driver interface. This work is supported by a very understanding spouse and quite a lot of black pekoe tea.
What's New in This Release:
Changed order of conditional includes in parapin-linux.h to build on more distros without problems
fixed Makefile bug that caused parapindriver.h not be installed when modules were installed
small documentation and commenting cleanup
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