Advice on Use

Including the Library

To use this library you must:

Correctly Include the Header File

The header file rpiGpio.h must be included in whatever source files use a GPIO function i.e. #include "rpiGpio.h". You will also need to ensure that your compiler can find this header file. In GCC you can include the path to the directory the header resides with -I<dir>. E.g.

        gcc -I/path/to/RaspberryPi-GPIO-C/include/ -o <outputfile> \
                                                      <input_list>

Ensure the library is correctly linked when compiling your source.

There are several methods to do this in GCC. You can provide a direct path to the library as if it was another source file.

        gcc -I/path/to/RaspberryPi-GPIO-C/include/ -o <output_file> \
            <input_files> 
            </path/to/RaspberryPi-GPIO-C/library/libRpiGpio.a>

Or you can add the directoy which the library resides to the list of directories the linker checks for library files. The library path is specified with -L<path>. You then need to tell GCC that you want to use this particular library. This is done with -l<lib-name>. The lib_name is name of the library with the preceding "lib" and proceeding ".a" removed. libRpiGpio.a = RpiGpio

        gcc -I/path/to/RaspberryPi-GPIO-C/include/      \
            -L/path/to/RaspberryPi-GPIO-C/library       \
            -o outputfile <input_file>                \
            -lRpiGpio                                   

Library Functions

Initialisation

The first call which could always be made to initialise the library for use is gpioSetup(). It is in this function where the memory mapping of the pointer to the GPIO peripherals is done. gpioSetup() need only be called once, and afterwards - if successful - you may proceed use a pin as an output or an input.

Output

To configure a GPIO pin as output call gpioSetFunction() with the desired pin number and the function as output. You can now change the state of the pin with gpioSetPin(), passing in the desired pin number and either high or low.

Internal Resistor

Depending on the configuration you may want to configure an internal resistor at pin or perhaps disable it. To do this call gpioSetPullResistor() with the GPIO pin number in question and the desired resistor option. The internal resistor option is useful if you intend on using a switch, for example as you can generally get away without an external resistor. Just connect the switch to a GPIO and either GND / VCC with a pullup / pulldown resistor configured on the GPIO.

Input

To configure a GPIO pin as input call gpioSetFunction() with the desired pin number and the function as input. You can now read the state of the pin with gpioReadPin(), passing in the desired pin number as well a pointer to a type eState which will hold the current state of the pin after the function returns.

Cleanup

When finished with the GPIO pins, gpioCleanup() should be called which will unmap the memory used to access the GPIO registers.