WebIOPi doe snot work @ DietPi @ Raspberry Pi Zero W


  • DietPi_RPi-ARMv6-Buster.7z downloaded April 21st, 2021
  • Raspberry Pi Zero W v1.1

Try to boot from above image, then install WebIOPi using embedded optimized software installation system. It will not work. I mean, it will start a web service which is accesible but it does not work. For instance, it displayes the pinout pincture but you can do nothing. Not possible to define a pin as in/out or control it. Just does not work.

DietPi team, why to include something what does not work?

I am not expecting an answer, I switched to Raspberry Pi OS Lite. This is just to let you know about the bug.

Many thanks for your report. It would have been awesome to have some error logs to get an idea whether it is a general issue with WebIOPi or just a missing Python module or syntax (as of too old Python code). I’ll add what I have in case others find this thread.

WebIOPi has been last updated by its developer(s) over 6 years ago: https://sourceforge.net/projects/webiopi/files/

Since I’m quite inexperienced with GPIO in general, I never did a functional test but only maintained the install option coding-wise. It basically installs the RPi Python GPIO packages and runs the included setup script.

So indeed it would be great to have some people test it, especially if it works with current Python versions and firmware in general. It’s possible that it simply does not work on RPi Zero, since that board was announced half a year after the last WebIOPi release, which was about enabling RPi2 support.

I was thinking about removing it because it seems to required Python 2, which is not shipped anymore with next Debian release: https://github.com/MichaIng/DietPi/issues/3656

What I did find is two forks, which seem to enable RPi3 / RPi4 + Python 3 support:

But I didn’t want to change something until either me or someone else is able to test those functionally, also on the older RPi models.

As you switched to Raspberry Pi OS Lite, you did not try to or succeeded to get WebIOPi running there, did you?

I have an RPi1 to test around. It seems clicking on buttons doesn’t have any effect

Does the browser console show any error? Or the service log?

journalctl -u webiopi
cat /var/log/webiopi

To be true I’m not sure what effect it should have (visually). Never used it, as said. From what I understood, I ships an API, but one needs to write own scripts to actually use that API.

… reading, okay indeed pressing the buttons next to the pins in the diagram should toggle them, but not sure if that is visually visible in the UI, e.g. has any effect when not attaching something to the pins: https://www.raspberry-pi-geek.com/Archive/2014/06/Getting-started-with-WebIOPi

Browser console shows net::ERR_EMPTY_RESPONSE but I think that is as it runs in a container where it has no access to the GPIO. Will check some more things before installing it on the main system.

Further testing. I managed to get control over the GPIO states from within the container. There is a huge number of different tools to get/set those: gpio-utils, raspi-gpio, gpiod, pigpio-tools, pigpio … all show the correct state of my pins and I’m able to toggle them as well. However, the Python library should work without any of those CLI tools.

Since from console I can check and control all pins without issues, but the WebIOPi interface fails to even get the states, I suspect a Python version incompatibility. I’ll retest on Stretch with a lower Python version. Btw as it runs as root, permissions are not the issue. Another thing we might want to change away from the installer, if we ever (want to) get this working.

The debug flag btw does not reveal anything interesting. It shows the client requests which get a 200 response code, while the issue with empty responses are not visible.

EDIT: Same issue on Stretch. Now testing the other forks.

EDIT2: As additional test I installed WiringPi, as most guides around WebIOPi use the gpio command (which is WiringPi). It works fine, but doesn’t solve the issue with WebIOPi, which still fails to show any GPIO states.

EDIT3: Okay, and it IS related to the container. The newest fork provides a better error message (or maybe Python 3 is it, which is able to run it):

No access to /dev/mem. Try running as root!

I bind-mounted it into the container, but I think it has limited write access to that generic tunable.

EDIT4: Granted CAP_SYS_RAWIO to the container, BINGO, WebIOPi works flawlessly now on my RPi2 with Python 3.7. Will check again the original version.

EDIT5: Old version still fails, to there it is not an permission issue. Installed the newer fork with Python 3 on to of it and it works fine. PR up: DietPi-Software | WebIOPi: RPi 3/4 support + Python 3 by MichaIng · Pull Request #4310 · MichaIng/DietPi · GitHub

thx MichaIng doing to effort to migrate this old software title to a newer fork/version

Thanks :slight_smile:.

Now that I know better what it is and how it works, and couldn’t find any alternative, I found it quite useful to quickly switch input/output pins via browser, e.g. using the Node-RED web interface on the other tab.

You know, this was my initial plan, I soldered a header pin on my Pi Zero and just wanted to test some pins with use of Node-Red. It did not work at all, I could not install RPi-GPIO lib as described in another thread. I had no time to troubleshoot so I tried quickly to use WebIOPi but it also did not work…

As I was in a hurry, I quickly switched to Raspberry Pi OS Lite and did my tests within 5 minutes from taking the decision.

I was later checking this whole WebIOPi story and indeed it seems to be quite old. Maybe DietPi should consider removing it or leave some note about incompatibility with Pi Zero. Maybe on Pi 2/ 3 / 4 it will work, who knows, have no time to play too much at the moment.

BTW when you install Node-red with use of:

bash <(curl -sL https://raw.githubusercontent.com/node-red/linux-installers/master/deb/update-nodejs-and-nodered)

It asks you if to install automatically GPIO lib which makes sense on RasPi. It could be considered also in DietPi-Software (Optimized).

with next release, DietPi will switch to a different fork of WebIOPi that’s working way better


Still question if RasPi Zero /W will be supported. If not, an added note would be appreciated.

I tested it on a RPi1. Most probably it will work on a Zero W as well. It would be helpful if you have a spare SD card and could try it out.

It was not working on any RPi model, I guess due to incompatibility with recent Python versions. RPi Zero is not listed explicitly, and we couldn’t test it (no RPi Zero here) but as Joulinar said: as it works on RPi 1 it should do on Zero as well, as they have the same 40 pins.