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Feature requests for new hardware

Hi all!

We hope you are doing ok!

This post is coming with some (good) news :boom: . We are coming out of some long (tough-ish) time after the pandemic and some components crisis, and we are coming back to the forum to start thinking about what’s next, and what we can do together. As you know, the SCK is currently not available, and the reason for it is because there are have been some components that have either been discontinued or that had supply chain issues.

We are working on it, and we would like to make some hardware changes and ask you about what you think about some ideas. We would really love if you could share with us some feedback from the usage of our beloved SCK2.1 :heart:, which of course has its good and bad things, for which we would like to keep the good and improve the bad… These changes will in principle be backward compatible in both boards, so new and old versions of the hardware (SCK2.1 onwards) will be interchangeable :slight_smile:

So! These are some working topics, and we would appreciate some input, requests, comments or anything you want to contribute.

Urban Board and Sensors

  • We would keep temperature and humidity, noise and PM sensor as they are.
    • For the temperature sensor, maybe a slight improvement to add a PTFE protective layer.
    • To allow other PM sensors (Sensirion, and many others), some designs for bridging connectors will be done and shared, and firmware will support some
  • We have to replace both the pressure and the tvoc sensors because they are discontinued.
    • Pressure sensor seems to be somewhat simple, and replacing it with another one with similar specs would do in our opinion
    • tVOC sensor seems to be a tricky one, and the CCS811 has shown that technology is not there yet for the complexity of the tVOC measurements. We are looking into some alternatives, but still no decision has been made.
  • We have received a lot of feedback for changing the light sensor, maybe into something less directional. We are also looking for some UV sensors, but there isn’t much out there.

Data Board

  • We are thinking about expanding the Data Board header to a much larger one and expose more pins. This would allow us to connect for instance to external communication modules (LoRa, GSM :eyes: ?) or to develop boards that can be hooked up to other sensors, without going through the auxiliary connector
  • We are also testing some new RISC-V ESP32 C3 to replace the current ESP8266. This would allow us to go into other network types, improve connectivity and do plenty of cool things!

We would love to hear what you think about it, either by contributing some sensor ideas, some other feedback, or even just talking about what is good or bad of the current hardware.

Also, the firmware development will happen in the github repo in case you want to contribute!

1 Like

Dear @oscgonfer ,

Thanks for reaching out for feedback.
For the SD card I would love to see the replacement of the spring slot with a friction slot.
In my enclosure I sometimes had bumps on the bicycle pop out the SD card.
With my Raspberry Pi I also had one break so I’ve been very careful and apprehensive about the same thing happening on the SCK.

The raspberry Pi went through the same thing and eventually they moved to a friction slot:

I wonder if a friction slot will also take slightly less space on the board?

Kind regards,

I’m glad that tvoc/co2 sensor will be replaced since it is really useless sensor (at least outdoor in lower temperatures).
It would be nice, if you could use sensors, which are also working outdoors in winter temperatures (here I mean at least something like -10°C).
Also better humidity protection on PCB would be nice.
In the new firmware I suggest, that the data will be also visible locally via web server. Just some JSON file with all the actual values/data available via webserver on the local IP of the WiFi adapter.

Last comment is about PM sensor. I think there is quite a big error in environments with higher humidity (fog etc.), may be another version can deal with these situations?

Thanks for your great work
Marek Drapal

Hi @cyrille.mdc1

Thanks for the feedback. We will certainly take this into consideration, it’s a very good one!

Hi @marek.drapal

Thanks for the feedback! Absolutely, the tVOC is quite a complicated sensor (and VOCs a very complicated thing to measure). Some promising (not perfect of course) options are the SPG40 (tVOC), the SPG41 (tVOC + NOx (and O3)), the ENS160 (tVOC), BME688 (tVOC) and ZMOD4510 (NO2 and O3), which could at the moment be potential replacements. We have to say, after some years working with MEMs MOx, that no sensor will be perfect though, and that for more advanced measurements the aux port will be there to help (or the new port on the data board), but the better the base option is the better, fully agree.

Humidity is also an issue, at least better protection of the SHT31, but there are issues protecting the other sensors on the urban board in general because of the shape of the device itself. I would say that a lot of effort has been put into protecting them from humidity with the help of the enclosures, that have now quite a few options available for download and 3D print in the enclosures repository. Nevertheless, I share this frustration and we will try to improve this from the source as it’s possible. If you also have some ideas, please put them here! :smiley:

Regarding the firmware, that is a very nice idea, and the idea of migrating to the ESP32 is to make exactly things like that. Imagine having a small web app to check your data directly from the kit, and to see if the data is online by making a simple request. We have to say though, that even if the hardware will allow for this in terms of capabilities, the firmware will based on the current one for backward compatibility, and that it will take a while to be implemented - but hey, we welcome contributions too! :smiley:

Finally, regarding the PM sensor: the idea is that the Urban board will still have a connector for the PMS, but that either custom cables or adaptor boards will be available (we will see how), to connect the urban board to other (better?) PM sensors. Some sensors we have in the horizon are the Sensirion SPS30, the SEN50 and the Tera NextPM (this last one claims to be better when dealing with humidity growth of particles). Ideally, with a new firmware that we are working on, all these sensors can be more easily implemented/able, and we can be more flexible on what we can interface with.

Hope this somehow contributes!


Hi @oscgonfer
Thanks for your reply. For me, the NOx and O3 detection plus PM would be the perfect combination for urban environment monitoring. Of course tVOC is also interesting, but much less compared to NOx and O3 when monitoring most problematic emissions in the cities.

As I can remember, the webserver is already implemented in actual firmware, is this a memory consumption problem, that it can’t run in the measuring mode?


Hello again,

I forgot to add, it would be great to have a physical switch, or pcb holes/pins to connect a switch to. Two main reasons:

  • I had some battery consumption problems with the connected GPS. Something that allows the ‘hard off’ of the device would be great.
  • I had participants using the sensors for experiments and they found the button tricky to figure out (5-6 seconds was too long for them to see any effect).

I also agree with @marek.drapal about NOx being more interesting than the tVOC due to the latter’s sensitivity and also complexity of VOC sources.


Hi, thanks again for the input.

I think adding a normally closed jumper with pads that can be cut to add an external switch could work, and wouldn’t hurt us. We will see if there are any potential downsides.

NOx is way more interesting outdoors for sure, but we have to see how good the sensor is. Those pollutants normally are not somewhat reliably measurable unless using electrochemical, but we’ll see!

VOC is still in the horizon, but maybe we think of different sensor boards with different purposes? Still somehow undefined.

Just recently I have noticed (and ordered) that Seeed now have a trickle of Smart Citizen Kits become available. I ordered one for spare parts.

But really looking forward to the new version becoming available.