Tag: rasppi

Raspberry Pi 2 vs. 1 GPIO Benchmark

Raspberry Pi 2 GPIO Benchmark

It’s battle time! Some of you may have heard that Raspberry Pi 2 is out with more punch than ever. Just how much more? Well, apt-get dist-upgrade went about 5 times faster with the new Pi. With 1 GB of RAM and four cores, this will definitely be a boost for my home SSH box ergonomics over the previous version.

But what about hacking? There has been a lot of interest in getting GPIO benchmarks for the Pi 2 similar to my earlier Raspberry Pi GPIO benchmark. Well here it is! Please refer to the earlier article for source code and nice screenshots of square waves, as I’ll concentrate on the performance difference only here. You can also get the code from Github:

https://github.com/jokkebk/rpi-gpio-benchmark

Summary of results

All the Pi 1 benchmarks were ran 14th and 15th February 2015 using latest versions of the libraries as stated in my updated benchmark post. Pi 2 benchmarks were all run 25th and 26th March 2015 with the latest versions. If you get significantly different results at a later date, please let me know and I’ll update the table!

Language Library Pi 1 Pi 2 Change
Shell /proc/mem access 2.8 kHz 7.0 kHz 2,5x
Shell / wiringPi WiringPi gpio utility 40 Hz 95 Hz 2,4x
Python RPi.GPIO 70 kHz 243 kHz 2,5x
Python wiringpi2 bindings 28 kHz 103 kHz 3,7x
Ruby wiringpi bindings 21 kHz N/A 3,7x
C Native library 22 MHz 41.7 MHz 1,9x
C BCM2835 5.4 MHz 7.2 MHz 1,3x
C WiringPi normal GPIO wiringPiSetup() 4.1 MHz 9.3 MHz 2,3x
C WiringPi GPIO wiringPiSetupGpio() 4.6 MHz 9.4 MHz 2x
C WiringPi sys wiringPiSetupSys() 120 kHz 185 kHz 1.5x
Perl BCM2835 48 kHz 154 kHz 3.2x

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Raspberry Pi GPIO Benchmark Updated!

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The new Raspberry Pi model 2 is out and the Pi world seems more popular than ever. My 2012 benchmark of different RaspPi GPIO access methods has been getting a lot of hits, so I thought to revisit it, and have now updated all the benchmarks with latest versions of firmware and GPIO libraries. I’ve also upgraded my oscilloscope to PicoScope 5444B, so the scope bandwith limitations I had earlier are now gone. :)

Because the benchmark has been linked from many other sites, I’ve just updated the old post to keep links pointing to right places.

Read the updated Raspberry Pi GPIO Speed Benchmark!

Raspberry Pi Serial Console With MAX3232CPE

In addition to the audio, video, network and USB connectors, the Raspberry Pi also has 26 GPIO pins. These pins also include an UART serial console, which can be used to log in to the Pi, and many other things. However, normal UART device communicate with -12V (logical “1”) and +12V (logical “0”), which may just fry something in the 3.3V Pi. Even “TTL level” serial at 5V runs the same risk.

So in this short tutorial, I’ll show you how to use a MAX3232CPE transceiver to safely convert the normal UART voltage levels to 3.3V accepted by Raspberry Pi, and connect to the Pi using Putty. This is what you’ll need:

  • Raspberry Pi unit
  • Serial port in your PC or USB to serial -adapter
  • MAX3232CPE or similar RS-232 to 3.3V logic level transceiver
  • 5 x 0.1 uF capacitors (I used plastic ones)
  • Jumper wires and breadboard
  • Some type of female-female adapter

The last item is needed to connect male-male jumper wires to RaspPi GPIO pins. I had a short 2×6 pin extension cable available and used that, but an IDE cable and other types ribbon cable work fine as well. Just make sure it doesn’t internally short any of the connections – use a multimeter if in doubt!

The connections on Pi side are rather straightforward. We’ll use the 3.3V pin for power – the draw should not exceed 50 mA, but this should not be an issue, since MAX3232CPE draws less than 1 mA and the capacitors are rather small. GND is also needed, and the two UART pins, TXD and RXD.
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Raspberry Pi arrived today!

A rather long wait ended today, when DHL dropped this little package off at work in the morning. I had placed my Raspberry Pi order in the first 24 hours when they started taking orders (or actually, registrations of interest) from RS Components, but it took about two months for me to receive the invitation to order, and three more weeks for the order to arrive.

Opening up the box, I was greeted with a very small computer, and two small leaflets, a quick start guide and a regulatory and safety pamphlet. The board is really quite small, just a few millimeters larger than a credit card. Two USB slots, HDMI, coaxial and stereo audio plugs and micro-USB for power, plus an ethernet jack.

I ran a quick test to see if everything worked. Initially, there was flicker on my projector (the only device with native HDMI input I currently have), but that turned out to be incompatibility with the HDMI switch I had – without it it worked just fine. I used the premade Debian image on a SD card and it worked perfectly.
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