![]() Since 2012, the WiringPi performance has somewhat decreased, as I originally got 7.1 MHz from the GPIO access method. The performance is increased slightly to 4.6 MHz: There’s also a GPIO access method which involves calling wiringPiSetupGpio() instead of wiringPiSetup(), and using the normal GPIO numbering instead of wiringPi native renumbering system, so 7 becomes 4 in the above code. With the normal GPIO access method, the library already clocks an impressive 4.1 MHz square wave: It’s a popular one and quite easy to use. Gordon Henderson has written an Arduino-like wiringPi library using C. The performance is not far beyond the earlier C example: A solid 5.4 MHz with the use of -O3 optimization flag. INP_GPIO(4) // must use INP_GPIO before we can use OUT_GPIOīcm2835_gpio_fsel(PIN, BCM2835_GPIO_FSEL_OUTP) I took the example program and simplified the main method after setup_io() to this: The interfacing is slightly more difficult, but code isn’t too bad. The Raspberry Pi Wiki gives a nice C code example for true hardware-level access to the GPIO. Performance is about the same as Python version, around 21 kHz square wave is generated: WiringPi also has Ruby bindings, which can easily be installed: New test version with wiringpi2 module has improved to 28 kHz: Earlier tests with older version 1 gave a 19.5 kHz square wave. I installed the newer WiringPi2-Python version. Installation requires cloning the respective version and apt-get installation of python-dev and python-setuptools. ![]() Python with WiringPi2 bindingsĪnother alternative for Python are the wiringPi Python bindings. I originally got errors while trying this, but upgrading my packages solved that problem. Note that the new version requires some additional steps in installation, name getting Python development kit with sudo apt-get install python-dev. ![]() The improved performance in Python is probably enough for simple multiplexing and LED PWM applications. As of version 0.5.10, the rate has again increased, and is now around 70 kHz! 0.2.0 was less than 1 kHz, but 0.3.0 already bumped this to 44 kHz. The library performance has increased steadily. tar.gz file, extract files and run python setup.py install. Installing it was simple: Just download the. One of the simplest ways to access the GPIO with a “real programming language” (sorry bashers :) is with the RPi.GPIO Python library. WiringPi comes with the gpio command, but its performance is almost 100x slower (40 Hz) than the plain shell, possibly due to starting delay of the executable. Update: Note that I have my probes at 1:10 setting, so the actual voltage value is 10x what is displayed in the figures! Shell with WiringPi gpio utility For turnings things on and off this is enough, but no signalling and hardly even LED PWM is feasible. For some reason, this figure has come down since 2012, when I measured 3.4 kHz. Here’s a simple shell script to toggle the GPIO 4 as fast as possible (add sleep 1 after both to get a nice LED toggle test):Įcho "out" > /sys/class/gpio/gpio4/directionĪs expected, the performance of this implementation is not good: A 2.9 kHz square wave can be generated using this method. The easiest way to manipulate the Pi GPIO pins is via console. This is basically the “upper limit” for any signalling one can hope to achieve with the GPIO pins – real-life scenarios where processing needs to be done would need to aim for some fraction of these values. GPIO 4 was selected due to easy access and no overlapping functionality. The basic test setup was to toggle one of the GPIO pins between zero and one as fast as possible. :)ĭon’t try this at home! Shorting GND and VCC with a probe might fry your Pi and more! Method and Summary of Results The scope has also been upgraded to a PicoScope 5444B with better resolution and bandwith than the earlier models. UPDATED: ! This article has been very popular, so I’ve now updated all the benchmarks using the latest firmware and library versions. UPDATE2: You may also want to check out my Raspberry 2 vs 1 GPIO benchmark!
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