Perror ( 'Error writing to /sys/class/gpio/gpio24/direction' ) įd = open ( '/sys/class/gpio/gpio24/value', O_WRONLY ) Perror ( 'Unable to open /sys/class/gpio/gpio24/direction' ) Set the pin to be an output by writing 'out' to /sys/class/gpio/gpio24/directionįd = open ( '/sys/class/gpio/gpio24/direction', O_WRONLY ) Perror ( 'Error writing to /sys/class/gpio/export' ) Perror ( 'Unable to open /sys/class/gpio/export' ) Int fd = open ( '/sys/class/gpio/export', O_WRONLY ) Export the desired pin by writing to /sys/class/gpio/export Will toggle GPIO24 (physical pin 18) at a 100 millisecond rate for 10 Here is an example program that toggles a GPIO pin every 100 milliseconds:Įxample of programming GPIO from C or C++ using the sysfs interface on This is straightforward to do from C or C++. Sysfs ExampleĪs covered earlier in part 3 of this series, you can access GPIO pins through the file system using the sysfs interface.

The examples will also be valid C++ programs. In this installment we'll look at a couple of ways to control GPIO hardware from the C programming language. But you often can do soft real-time, such as reading buttons and slow sensors, driving LEDs, motors, etc.

That said, you still should not expect to do hard real-time programming under a standard Linux-based system. There is also no need to ship full source code to end users.

If desired, you can look at the compiler's generated code or even use in line assembly language. Because you are working closer to the level of the hardware you don't have to worry about what a JIT compiler or interpreter might be doing. However, true compiled languages like C or C++ can offer some advantages in embedded applications, such as higher performance. Python offers a number of advantages as a programming language including a short learning curve, no need for compilation, and the availability of many add-on modules. My last post, part 4 in the GPIO Programming series, showed some ways to program GPIO from Python.

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