We normally meet every second Tuesday of the month for talks and demonstrations from 7:00pm onwards at BCB Radio in February, May, August and November and online in other months.
Why not come along to a meeting?
Until the start of the pandemic in 2020, some of us used to create IT Stuff for BCB Radio (106.6 FM). Shi has looked back on this for us.
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.
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.
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.
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.
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.
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.
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.
Mike raised a problem he had had. Having changed a setting, he was unable to get back in to change it back. He knew where to make the change but could not find a way to get there. John suggested SystemRescue which has the virtue of not touching anything unless you tell it to do.
Once running, enter:
fsarchiver -v probe
to identify the partitions and their names. Mike can then mount the relevant partition in /mnt
, go into the partition, make the change, for example, with nano
and quit.
Calyx meet was down for maintenance and Brian wasn’t around to invite people to Discord; so we used the openSUSE Jitsi instance.
Darren said that at the York CoderDojo he had had a go at code golf in which people aim for the shortest possible code to solve a particular problem.
Mike said that, while Ansel, the fork of darktable, is being cleaned up, it has still got a fault in it; so he has been using Rawtherapee + GIMP but will go back and look at Ansel; Bernie noted that there has been a new release of darktable at Flatpak.
For the first of our new style online meetings, Bernie, Darren and John started on Discord while Steve and Mike started on Calyx meet before we all moved to Calyx meet where we were joined by David and John W.
Mike has had a problem with sound disappearing; John suggested that he use PulseAudio to diagnose which sound sources are recognised and whether any have been muted. Mike has also had a problem with darktable and has been told he needs to get a coredump. But for that he needs the devel files and to compile darktable with -g
set. Steve looked up the source on github which provides all the information about how to build darktable.
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