How to order/Build

[Flipez]

Hi and thanks for all the work!

I am interested in building some of them myself. Looks like I have to order pretty much everything myself. Could you give some hints/links on how to do that?

I've worked with a lot of sensors and smaller electronics in the past but never actually build/order my own pcbs. So I am a bit lost on that.

Thanks in advance!

[janpfo]

@janpfo I've been using this Plastik 70 frmo Kontact Chemie.

The missing LED should be okay, but you can essentially select any other red 0402 LED from JLCPCB.

Thanks! I got a question from JLCPCB. Looks like JLCPCB inverted the photoresistor. Is this wrong?

Since we are not so sure about the polarities of the components Q4 are correct or not. Could you please kindly check if the polarities and placements of the components are correct in the below picture? Is it okay to proceed with production?

[rbaron]

@janpfo In the render, we can see Q4 connected to the SoC pad and to GND through the resistor R10. So the collector should be on the left (side connected to the SoC pad) and the emitter on the right (connected to GND through R10).

[janpfo]

@janpfo In the render, we can see Q4 connected to the SoC pad and to GND through the resistor R10. So the anode should be on the left (side connected to the SoC pad) and the cathode on the right (connected to GND through R10). I believe this is configuration in the (corrected) right render, assuming the red vertical bar represents the cathode.

I looked at the schematics, and it looks like the original is correct. If the numbers on the schematics and render is correct. The "1"-side should be connected to pin 8.

[rbaron]

@janpfo I would try clarifying with JLCPCB which pin represents the collector (pin 1 for us) and the emitter (pin 2 for us) in their footprint. Hopefully both us and them assign the same pin numbers to the footprint, but I'd still double check. Please let me know what they reply.

Looking at their product page for the phototransistor, it seems like the vertical bar represents pin 1, and not the electrical characteristic (like in a diode symbol):

In this case I believe the left render is indeed correct (pin 1 on the left).

[janpfo]

@janpfo I would try clarifying with JLCPCB which pin represents the collector (pin 1 for us) and the emitter (pin 2 for us) in their footprint. Hopefully both us and them assign the same pin numbers to the footprint, but I'd still double check. Please let me know what they reply.

Looking at their product page for the phototransistor, it seems like the vertical bar represents pin 1, and not the electrical characteristic (like in a diode symbol):

In this case I believe the left render is indeed correct (pin 1 on the left).

Looks like the original render was correct. Collector on pin 1 and emitter on pin 2.

[a83r]

Hi, help would be appreciated. JLCPCB "corrected" the layout. I see they changed part Q4 and U2 is this correct? As I understood that Q4 has the correct position what is with U2?

First is the original

Second is corrected by JLCPCB

[a83r]

Ok, I checked myself with PCBEditor and found that U2 is in the second picture correct but Q4 in the original.

[rbaron]

@a83r,

can I ask you to please crop/resize those images? Thanks.

On the comment above yours, @janpfo and I discussed this same issue with Q4. The conclusion was that Q4 was originally correct. @janpfo did you manage to order the boards? Was the orientation of Q4 correct? Thanks!

U2 seems to be correct in the corrected version - the dot should align with the footprint.

[a83r]

@rbaron It looks like that JLCPCB spins U2 in the original picture (maybe a bug?) but shows it correctly in the corrected version. But in the DMF overview, they don't state that they changed Q4 only U2.

I cropped the pictures, sorry I was little panicked as I didn't expect them to ask such questions....

This is how my DMF Overview looked like:

I told them that Q4 was rightly placed in the original upload as well as U2

[rbaron]

No worries @a83r. It's usual that they analyze and suggest these adjustments. Just to be clear, U2 seems correct in the corrected version. The difference is in the red dot. In the second (correct version), it correctly aligns with the footprint dot. The convention is that the dot identifies the pin 1 of the package, so they should match.

[janpfo]

Sorry for my

@a83r,

can I ask you to please crop/resize those images? Thanks.

On the comment above yours, @janpfo and I discussed this same issue with Q4. The conclusion was that Q4 was originally correct. @janpfo did you manage to order the boards? Was the orientation of Q4 correct? Thanks!

U2 seems to be correct in the corrected version - the dot should align with the footprint.

@a83r,

can I ask you to please crop/resize those images? Thanks.

On the comment above yours, @janpfo and I discussed this same issue with Q4. The conclusion was that Q4 was originally correct. @janpfo did you manage to order the boards? Was the orientation of Q4 correct? Thanks!

U2 seems to be correct in the corrected version - the dot should align with the footprint.

Sorry for my late reply. Can confirm that 4/10 boards that I ordered works.

If you are soldering the nrf chip, don't do the same mistake as I did. Use flux when soldering and apply solder to the pad before soldering the chip. Learned that the hard way 😅

[drspangle]

I just placed a batch order for 15 of these from JLCPCB with SMT assembly. I had to order the BTLE chips from AliExpress as they're still on backorder, but I managed to get a significant bulk discount on these and the battery clips. Hoping I'll be able to get at least 10/15 boards brought up. I'm also working on ordering the cases from Shapeways, they're very expensive as a one-off order so I'm hoping I can get a bulk discount. Anyone know where I can get the cases 3d printed (FDM or SLA are both fine) for cheap?

[RAYs3T]

@drspangle Any chance you want to sell 2-3 of these? :) - I could also offer to print you some cases in black or white PLA with my Voxel 3D printer.

[a83r]

@drspangle

Hey, I ordered 15 cases at craftcloud I paid for all of them with PETG (translucent) 46€. Mabye you give it a try aswell? For future reference, you can buy the chips from Ebyte directly on alibaba I paid for 15 pieces 96$ + Shipping + VAT

Get yourself a good amount of solder flux as well, it helps a lot to solder the chips to the board.

And coat the whole front of the sensor as well. I coated only the bottom part, in the last days there were pretty heavy rain and wind. 5 of my sensor did stop working because of water inside the case. I cleaned all of them and coated now the complete front side as well.

[drspangle]

@RAYs3T Let me see if I can bring them up, first. I just placed the PCB, battery clip, and chip order today (got them from AliExpress for about the same price as @a83r quoted). It will take a few weeks for this all to arrive. I will update when I've got these in hand. I'd also like to see if I can update the case design to use less material (see #34) but I'm running into issues there. We can maybe negotiate something when I have some extras to sell you (assuming all goes well).

@a83r Thanks for the advice. I've got an entire tube of ChipQuik and I am a friend of Louis Rossmann so I've learned that too much flux is never enough. I also bought conformal coating (I opted for the polyurethane based rather than acrylic) and I plan to cover everything except the pads for the serial interface and the battery clip. I'm hoping that I will be able to work out a case design that improves the water resistance a bit, even though I plan to only use these indoors. It may come down to a multi-material print incorporating a TPU gasket and two very small screws, but I'm also trying to make these as low profile as possible, so we'll see what I can come up with.

Thanks all for the help and advice. Looking forward to the parts arriving so I can get hacking. By the way, has anyone had any luck with progammers other than the ones from J-Link? They're sold out everywhere so I thought I'd try my luck with this one: https://www.amazon.com/gp/product/B09KXSJ31D/ It's got free returns, so if it ends up being not fit for purpose (despite allegedly being compatible with cortex-M) I'll have to see if I can get a J-Link one instead, but it might take some time to find a supplier.

[antonio-fiol]

@drspangle where are you based? I'm happy to print all your 15 cases in PLA if I can get a couple of boards from you (is that reasonable?), but afraid that shipping cost to/from Madrid, Spain may break the deal.

[drspangle]

@antonio-fiol I'm in the USA, so I don't think this will work. All the same, perhaps you could 3d print my updated design and let me know if it fits the sensor? I actually didn't reduce the amount of material much, but I did add some features designed for the 1.2.x hardware iteration (battery clip shouldn't matter).

There are added holes to permit gas exchange for the humidity sensor, a new cutout for the photosensor (should be especially useful if the case is printed in a dark/nontransparent material, which I think would be preferable for some settings), and cutouts designed to make it easier to pry open the case to replace the battery, especially if they are printed with tight tolerances or if the conformal coating makes the case stuck shut.

Check out my pull request #35 containing the updated STL and STEP files -- do you want to try printing it and see if it fits well?

[antonio-fiol]

perhaps you could 3d print my updated design and let me know if it fits the sensor?

Well, I could certainly print it, but I don't have a sensor yet, and I don't think I have need for a large batch.

[tispokes]

Has anyone thought about the surface finish? Isn't the cheapest finish non-leadfree and maybe bad for the plants? Or even worse if you grow herbs?

[chucknorris101]

Hi - relative newbie to all this, but the directions seem pretty straightforward! Thanks!

@rbaron I did have one question, on surface mount soldering the NRF (see underside picture), there are pads 'underneath' how do those get attached or are they not used?

[rbaron]

@chucknorris101 they are not used. Happy hacking!

[chucknorris101]

In planning my 'rollout' of sensors around the house, i have alot of smaller pots/plants to track, the original boards were a bit shorter, it seems simple enough to edit the gerbers to shorten them again...

What about shortening the capacitive loop? It would change the measurement/calibration for sure, but wondering what I should avoid when tinkering with the files. If not known, maybe i will order a few with different geometries and test it out. It seems like most capacitive soil sensors have the same general shape, but wondering if there is more background to be found on the web? everything i find is about how to not get it (though maybe something to be learned there) - is there anything to avoid as far as changes? i.e. trace thickness, multiple loops? or what is the general principle behind the long oval?

[evlo]

after uploading gerber lot of the parts are not placed

I went by the guide uploaded bom and th topthing, but i think I must did something wrong.

In the parasite-top-pos.csv there is line "Q3","AO3407","SOT-23",73.100000,-57.300000,90.000000,top but then it does not appear, or I do not understand if it appears in preview and bom review step

[rbaron]

@evlo that was a mistake from my side. I reverted the offending commit on the main branch.

[cesar73AGP]

Hello, I am from Spain and I would be interested in buying several sensors for my plants. how can i buy them? Congratulations on the project, it's fantastic

Thanks in advance. a greeting

[TheSmartGerman]

Hallo, @rbaron would it be possible to make a shared project from the sensor?

I know PCBWay does support this: https://www.pcbway.com/project/

It would make it easier to order the sensor.

Thx

[dlavey]

Does this look right?This is my first time ordering and I want to make sure I don't end up with a bunch of useless sticks. I swapped out the E73-2G4M08S1C with a E73-2G4M08S1EX (I believe that'll work based on the wiki) and it didn't seem to place correctly so I moved it into this position. I also had to rotate Q4 to match another comment here. I also played with U2, but I think I ended up putting it back the way it was.

[TheSmartGerman]

Hallo, @rbaron would it be possible to make a shared project from the sensor?

I know PCBWay does support this: https://www.pcbway.com/project/

It would make it easier to order the sensor.

Thx

Here is a projekt available now: https://www.pcbway.com/project/shareproject/W579466AS2D1_b_parasite_main_bc61bf0b.html

I don't have a login yet. Did someone ordered this already?

[TheSmartGerman]

ok, I'll do a dry. PCBWay checked the gerber and have this question: "there is via in pads design,we will make vias filled with resin to make sure good soldering"

What's recommended, fill these vias in pad? Fill all vias on pcb

thx

[lightingman117]

As shown, there are some vias designed in pad, we suggest to do via-in-pad (vias filled with resin) to avoid poor soldering. Please check and confirm which one should we follow? A. Do not do via-in-pad, is ok for the risk of poor soldering. B. Do via-in-pad to the vias designed in pad only. C. Do via-in-pad (vias filled with resin) to all the vias. Looking forward to your reply, thanks.

I saw the PCBWay project and wanted to try it too. Same question.

I haven't had time to research what a vias in pad is?

Edit: Learning from: https://www.protoexpress.com/blog/via-in-pad-pcb-design-manufacturing/

[rbaron]

Hey @TheSmartGerman, @lightingman117. We have some vias in pad like these:

It means that through-hole vias are placed directly on top of a footprint pad. Some designers stay away from it because the solder can "leak through" the via while soldering a component in the pad. I believe this is why PCBWay is offering to fill the vias with resin.

I haven't used PCBWay, and with the default JLCPCB settings I use I don't think there's any special treatment for these vias in pad. I have not had any issues of that so far, although most of the time I solder the module by hand, where it's less of an issue.

[TheSmartGerman]

@rbaron Thx, I ordered at JLCPCB finally and received my delivery this week. With the resin filled vias, a single pcb was more than 10$.

This weeked I'll hopefully can give a try to flash the nrf.

[lightingman117]

@rbaron thanks! I'll let them do the epoxy fill

Question, for part 7, designator Q1, MMBT3906 they want to substitute with MMBT3906LT1G due to availability.

https://www.diodes.com/assets/Datasheets/MMBT3906.pdf https://www.onsemi.com/pdf/datasheet/mmbt3906lt1-d.pdf

[rbaron]

@lightingman117 These two have the same name, but are from different manufacturers, so it's still worth checking if they are compatible. You need to check 1. if the pinout between the parts is the same (Base, Collector, Emitter) and 2. if they have similar electrical characteristics (there's a table in both datasheets called just that). At a super quick glance it looks okay, but please double check these points before ordering.

[lightingman117]

@lightingman117 These two have the same name, but are from different manufacturers, so it's still worth checking if they are compatible. You need to check 1. if the pinout between the parts is the same (Base, Collector, Emitter) and 2. if they have similar electrical characteristics (there's a table in both datasheets called just that). At a super quick glance it looks okay, but please double check these points before ordering.

Thanks, I did compare the datasheets.

The primary difference that I see is V_EBO is -5Vdc instead of -6Vdc, I don't see how that could be an issue...but I didn't really look at the schematics to even start to understand them.

I'll just wing it and say yes.

Worst case I have to do some SMD soldering lol.

[spitfire]

Is there a place one can order a ready-made one? I'm not great with soldering and this would be way out of my league.