ELEKTOR FORUMS

Maybe I'm just getting old, and the world of electronics is leaving me behind. I've taken Elektor Magazine pretty much uninterrupted since the early 70s and have seen it grow from the typical-of-the-time hobbyist magazine, to the global publication that it now is. However, recently I've become more and more disillusioned with some of the content and the way it is presented. An article in the current issue is what has prompted me to write this missive. The article that I am referring to is the Homelab Weather Station.

In the past, articles for constructional projects were always fully vetted by the magazine, to include editing, re-photographing, parts check availability and most importantly, building one to ensure that readers could reproduce a working version. And so it was with some excitement that I started to read the article as for some time, I have been looking for a new weather station to build to replace the (now mostly defunct) one that I designed and built twenty years ago. This one seemed to qualify for my needs pretty much exactly, right down to it finding a good practical use for the Raspberry Pi Zero W that came with my subscription this year.

The more I read, the more I thought that this was going to be 'the one'. For sure, there were a couple of warning signs that this might not be quite the case, in that there was a reference to the BMP180 sensor being difficult to obtain, but there was a substitute available. Also that there was an issue with the I2C address of the differential pressure sensor that was employed. However, I was fully expecting these issues to be dealt with in detail later in the article, along with descriptions of the code and what could be changed in it.

So I was very disappointed when I reached the end of the article and it concluded with a basic "That's it then folks. Thank you and goodbye ..." No code. No explanations of how to deal with the issues highlighted in the text. The section on construction was very poor. The photograph of the mounted unit bears little - if any - resemblance to the text which mentions four holes and a sealed piece of pipe. Not a multitude of holes and a big lump on the top as figure 9 shows. It also talks of screening in front of the holes - although none can be seen in the picture. How does this affect the calibration for the windspeed ?

I thought that there might be more details on the Elektor website, but I haven't been able to find anything.

I'm fairly computer savvy, and a professional electronics engineer, but that has always been analogue. I have ventured into using microcontrollers, but I willingly admit that I struggle a bit, so maybe the beefs that I have with this article - and others like it - are down to me, but I can't believe that I am the only long-time and older reader that finds this departure from the magazine's original basic concept of publishing complete and ready-to-build projects, less than helpful.

Don't get me wrong on this though. I fully understand that magazines like Elektor are in a difficult space, and that concepts and formats have to change to keep them in a viable place. I don't have a problem with experimental projects being placed in the online space, nor brief articles in the magazine outlining such projects, but I expect a multi-page article that has achieved whatever criteria are applied to determine that it goes to print in the actual magazine, to be a complete project ...

Sorry. Rant over now ...

Happy New Year all !

I think you are being a bit unjust as the article conclusion makes it clear that the article was "not intended as a detailed DIY Project" .

A bit of googling finds this useful page which links to the software https://www.elektormagazine.com/magazin ... 1801/41293 which is in file 160566-11.

Good luck, Peter

Thank you - but I think that you are missing the point a little. Must I now go to the end of every construction article first to see if it is complete, or just a bunch of ideas ?

I have tried building this project, but can't get the SDP610 sensors to work, I have changed one sensor to address 21 and both sensors show in i2cdetect -y 1 command as 21 and 40, but when I run the program it fails in module ReadDP at line result1 = (i2c.read ....) with IOError (Errno 5) Input/Ouput Error
I have tried enabling the time delay just before that line but it still won't work
All my other sensors work fine whilst on the same i2c bus as the SDP610 sensors, I have checked data sheet for pinout to make sure they are connected correctly, etc.
Any ideas how I can get this working?
I agree the description of mounting of the sensors leaves a lot to be desired and I am not sure the actual program works, after spending £90 on all the sensors, but BMP180's are easy to find on Ebay.


January 14, 2018 | 16:10
I have fixed the problem, you need to used the old i2c kernel driver, the current build uses bmc2835 and does not read the sensors correctly, going back to bmc2708 fixes the problem. To change the driver do the following,
sudo nano /boot/config.txt
add the following line near the bottom of the file
dtoverlay=i2c-bmc2708
save file and then reboot

The code supplied for this project is well commented but, unfortunately, in German. It's too bad that an English translated version was not provided instead. This kills the project for me.

The language is actually Dutch and I used Google Translate to copy and paste any text I wanted converted, then just paste back into the program - easy.

Kindly note that this article is clearly classified as a HOMELAB project (as opposed to an ELEKTOR LABS PROJECT). See also the final paragraph.

HOMELAB projects are purposely not passed through our lab to achieve perfect a PCB design and ditto software. Rather they show what our readers have accomplished with just basic assistance from Elektor staff in terms of graphics and text editing. The previous title for this category was Readers Projects which has been a part of Elektor since issue 1 in 1974.

The author of this project, Mr Zeno Otten is available at https://www.elektormagazine.com/magazin ... ents/33409

Jan

Yeeeesss. I get all that ... Might I suggest that the original title of Readers' Projects was rather better at describing the nature of the article than the current attempt at a 'fancy' title of "Homelab. Might I also venture to suggest, having taken the magazine since 1974, that in the past, readers' projects were not a 'mainstream' part of the magazine's format, and were not 'dressed up' to look like full blown projects. It is also my recollection that in the past, Elektor specifically differentiated itself from the likes of Practical Wireless and Everyday Electronics by only carrying projects that met very tight standards of design in terms of the concept, the availability of parts and the famous blue PCBs, all of which were handled by in-house design personnel.

As I said in my original post, I understand that times change and magazines have to move with them if they want to survive, but I also stick by what I said in that I would still like the printed paper magazine to contain projects that are 'ready to roll'. With the large online presence that you have, and the fact that readers' projects are likely to need a lot of discussion between both builders and the author, I still feel that the best place to present these in their entirety is in the online environment, with the printed magazine component limited to a basic description and the links to the full web article.

dmurrell wrote:...I have fixed the problem, you need to used the old i2c kernel driver, the current build uses bmc2835 and does not read the sensors correctly, going back to bmc2708 fixes the problem. To change the driver do the following,
sudo nano /boot/config.txt
add the following line near the bottom of the file
dtoverlay=i2c-bmc2708
save file and then reboot

Unfortunately this didn't work with the device that I am using. I can write to the SDP610 with i2cset but when I try to read from the device (with or without the overlay) with
sudo i2cget -y 1 0x40
the answer is always "Error: Read failed".

In Python the line
result1 = i2c.read_byte(SDP01)
causes this message:
"IOError: [Errno 5] Input/output error"

It seems that I'd have to inspect the signals on the i2c bus with a logic analyzer but this appears tedious and, as I am not too experienced with Python/Raspbian/C, might help me to understand what is going wrong but probably I wouldn't be able to fix the problem.

Any ideas are more than welcome.

Make sure that the sensor appears at the correct address using i2cdetect -y 1
I believe that you have to write to the device before you can get a read from it, hence the line i2c.write_byte(addr,ePresHoldCmd) in the ReadDP routine, have a look at the datasheet.