December 10 2024 Python GUIs, PPDs, Raspberry Pi Pi500

Bernie demonstrated how he had developed a Python GUI to provide a service needed in an astronomy context to an Instrument Neutral Distributed Interface (INDI). He needed a general purpose client but using ncurses was impractical as it doesn’t work in Windows. He first showed an example using ncurses running locally on a Raspberry Pi which turned an LED on and off by talking to the service.

When you import a GUI framework, you get a lot of widgets; he demonstrated with an example of the code used with Tkinter, the standard Python GUI, turning an LED on and off. The advantage of using the Gtk libraries is that they are on the Raspberry Pi and they are easy to install in Windows.

November 12 2024 Mariadb permissions, databases, visually impaired users, Stellarium

Mike had had problems in connecting MODX with mariadb. John wondered if this was a permissions problem as mariadb changed the way it handles permissions as set out during the meeting on 13 April 2021. Now there are five ways of handling permissions:

October 8 2024 Image sharing, Python, SD cards, SDR, AAX, Proxmox, Ventoy

Steve asked about photodisplay software; John mentioned that David had done a session on that many years ago when he had mentioned Panoramio [acquired by Google in 2007 and closed in 2016], Picasa [acquired by Google in 2004 and closed in 2016] and the bargain basement ImageShack [moved to a subscription based service in 2016] and Photobucket [moved to a subscription based service in 2017] but he did not know how many were still in action. [There is a list of active image-sharing websites on Wikipedia].

September 10 2024 Birthday review, Wuthering Bytes, uv

John gave a presentation marking our 16th birthday on topics covered over the past year. David queried whether the Raspberry Pi pop-up shop had closed and John said that he assumed it had as no-one had mentioned it for several months [it no longer appears in the list of shops in Victoria Centre]. David also said that an errata had been released relating to the GPIO pins on the RP2350 because a supplier had messed things up; unfortunately, if a pin is in an undefined state, it does not go high or low. Rather it creeps up high when you expect it to go low which affects some boards. This is mainly a problem for manufacturers rather than for hobbyists as there are workarounds and it might be fixed.

August 13 2024 Mars Rover, Pico 2 and RP2350, LyX 2.4

Bernie gave a talk on the Mars Rover’s unique suspension incorporating a rocker arm, bogey and differential cam mechanism which keeps the payload at the same height while keeping the wheels on the ground all the time. It is all done with linkages which ensure that the movement of one wheel up or down is matched by corresponding pressure on the other wheel to keep it in contact with the ground. This YouTube video is an animation of the action while this YouTube video of a scale model of the rover suspension demonstrates its operation.

July 9 2024 AWK, Alexa, Plasma 6.1

Brian commented that nmap is not working as it used to [as from 7.90, it changed its licence and is no longer considered free; the alternative would appear to be ZMap].

Darren is working on a demonstration of AWK, the data extraction program. He demonstrated some examples of basic conditional printing and of combining patterns to achieve more sophisticated results.

June 11 2024 Python+ncurses, Raspberry Pi Ltd, EMF Camp, Alexa

Bernie has been working on a console based interface which he can use with SSH to manage devices controlled through the Instrument Neutral Distributed Interface (INDI) using Python and the ncurses library.

In the specific example he demonstrated, he sent a new target to change the temperature. But in practice, by setting vectors to be values, you can have the controls to manage multiple devices, as long as there is a driver for the device. It can be used with any instrument though Bernie has in mind those using INDI.

May 14 2024 systemd, tailscale, Raspberry Pi Connect

As we were not able to have the expected presentation, we just discussed things we had encountered.

David noted the takeover of sudo by systemd.

Mike enquired about loading tailscale onto his Huawei smartphone and was recommended to use F-Droid.

April 9 2024 Giraffe Academy, jsDelivr, Redis, Tasmota

Mike has been getting on with MODX but had problems with cPanel; Brian recommended looking at Giraffe Academy which offers up-to-date information on things you can do in the HTML and CSS rather than Javascript.

March 12 2024 code golf, KDE6,YubiKey, MODX, pfSense

Bernie had circulated a Python3 script to address the first of the challenges set by Darren at the previous meeting.

The inclusion of an f"<string>" in Bernie’s script prompted a discussion of f"<string>"s. Bernie explained that you can include a variable within a brace in the string and also that you can use a format specifier followed by a : in the brace. David noted that every language has different format specifiers; C got them from the Fortran format operator.