Custom Shield - Indoor Air Quality Monitor


Hi @aj8uppal,
Nice work you are doing - keep it up :smile:
Its definitely superior to use a fan as per the Dylos.

I find the Grove Dust sensor to be quite good for $15. It correlates reasonably with my Dylos Pro. It achieves the goal of letting me know that there are more particles than expected - so I’m happy with that.

Perhaps one day the IAQ Shield V5 will have a Dylos Pro dust module in it :smile:


@aj8uppal I am currently running the DSM501A since I cannot get aworking Shinyei (the version grove sells) and it shows interresting results.

OOTB you can have P1 and P2 without addind a resistor, by default this is PM10 and PM2.5, I guess you add aa resitor to have something in between ?


Hi @zach
The discussions regarding improvements to the shield are scattered around the forums so I put everything in one place on my GitHub to make it easier to follow :

Do you think you will get a chance to look at this ?


Looks good @Rockvole! Anything in particular you want feedback on?


@zach, nothing specific - just whether the improvements look good for the final hardware design ? It would be good to complete the Kickstarter so we can move forward on manufacturing.


Hi @zach and @Rockvole,

This looks like such a great board. I was considering doing something similar, a board that could take several MICS / TGS sensors, and a Grove or two. I already have all the sensors.

Does anybody sell the old PCB? It looks like it will be about $40 to get printed off. Should I wait until the new one is ready?

This is exciting! Thank you for all your work on this so far.


Hi @kelvinn,
I use the board every day although I have modified it somewhat. I have made recommendations for improvements to the next revision. Some issues with the current design are :

  1. MQ ports have no ground connected so they dont work.
  2. MICS holes are for a sensor no longer made
  3. DHT22 cant get reliable readings because it is affected by heat from the PCB

My board also has a problem when the USB is unplugged there appears to be an oscillation on the board which destroys cores fairly quickly. Although a review of the board design didnt uncover any problems - so it is probably something which someone with hardware knowledge could fix for my board.


Thank you for the great response @Rockvole, I appreciate it. I noticed your air gap between the DHT22 (and using the separate Grove module). Looks like I’ll wait for the updated version, or simply create little mini boards for each sensor and connect via Grove.


I had the idea to distill the IAQ Shield into a simple Grove++ shield. This would meet my needs and I expect it would be cheap to manufacture, also it eliminates the complications of providing sensors.

Does this seem any good to you ?


Seems like a smart refactor, simpler’s definitely better. In this diagram, are you imagining the DHT22 vertically positioned to keep it away from the PCB?


That looks like a good approach. I’m currently in Shenzhen, China and should be able to quickly design and fab this PCB. Just one recommendation on the proposed layout: I’d suggest to move the analog grove sockets away from the PSU and onto the left side. What say you?


@zach - this was my idea for the DHT22 socket to keep it away from the PCB. I would attach it to the enclosure with a long standoff.

If possible it would be good if we can put an air gap in front of it (I marked an example in red).

The DHT22 is supposed to be horizontal - a standoff would pull it down to be parallel to the board


@mohit - I wanted the grove port pairs on separate sides of the board because the grove sensor wires are not that long and its tricky to put 4 sensors all together on one side.

Also, I wanted the digital ports away from the hot PSU incase someone wants a grove temperature sensor in that port (perhaps for one outside the enclosure).


@mohit - I would still like to keep the buzzer / led / switches from the original board, but I was hoping we can move to right angled switches and LEDs which will make it easier to fit in an enclosure?

Long pole switches would work better for sticking out the enclosure - I’m fine with having only 1 switch.

Right angle RGB LEDs are trickier to find - I’m fine with only 2 colors / separate LEDs if that’s easier.

Dialight also have LEDs where you can attach a right-angled light tunnel (optopipe) to it - which would work too.


@Rockvole Sounds like a plan. We can add the air gap as well. We should also orient the DHT socket to face the other way (facing outside), if your plan to put it in an enclosure.


Found these today at the local market:


You are having way too much fun over there :slight_smile:


Thank-you @mohit that looks good.

If you think of any ideas to reduce heat on the board that would be helpful - so we can get a good ambient temperature reading from the DHT22. I don’t know what would help - maybe a heatsink on the low voltage dropout regulator (or space to add one later if necessary), or maybe an upright low voltage dropout regulator (to keep heat away from the PCB).


An upright, through hole version would be better at keeping the heat away from the PCB. It may require a small heat sink if the user powers the board from a 12V supply.

I’ll start working on this design over the weekend and post the mock-up of the PCB before routing.

p.s. Everyone who loves hardware should spend a few weeks in Shenzhen in their lifetime. Heaven.


@mohit it does sound interesting in Shenzen - it would take me a month to get all those parts. Although I couldn’t live there - the air quality wouldn’t agree with me :wink: