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!

[drewzarn]

Seconding this somewhat, even a screenshot of what options to pick in the JLCPCB order form would be huge! I zipped up the gerber files and uploaded them, but I don't know what all options to choose to end up with a usable board. Thanks!!

[jaimevisser]

Or even getting some prepackaged kits would be awesome. Soldering everything together is not a problem, but having to source all the hardware and pcb's is the hardest part here.

[billypeanut]

Maybe if there's a big interest, a Kickstarter or something could be set up to do a big batch build/order of certain parts and reduce costs.

[jaimevisser]

I think most people have multiple plants to monitor so even with a few people you'd get a considerable amount of parts that can be bought in batch.

[spuiuk]

I am keen on obtaining some of these devices for my plants as well.

[rbaron]

I'm super happy to see everybody's interest here and thanks for the kind words! I am thinking about putting together a wiki in this repo with:

• Steps and screenshots on how to order it from JLCPCB
• How to solder the nRF module & battery clip
• How to protect the board & components from moisture

I'll ping this thread once it's up.

I agree with @jaimevisser. Sourcing the parts is not trivial - specially during this crazy chip shortage. In the 3 batches I've ordered so far, I had to source the nRF52 module from aliexpress at a higher price, as JLCPCB ran out. The battery clip also has to be sourced separately, since it's mounted on the underside of the board.

[Dza-byte]

I too am very interested in this! Commenting so I can get the ping when the wiki goes up. No experience with putting boards together myself

[MrEinstin]

I'm wanting about a dozen or so of these myself. I was also looking at the files and saw the gerber files but I didn't see the schematic? Perhaps I'm overlooking it somewhere. I'd also like to see a USB port for easier programming. I'd also second a Kickstarter campaign as well.

[rbaron]

Hey everyone,

I took a first stab at documenting the ordering process in the How to order: PCB fabrication and SMT assembly wiki page. Let me know what you think! Please feel free to contribute too.

It mostly covers my experience with ordering from JLCPCB, but I'd love to hear other peoples' experiences with other fab houses.

[rbaron]

Hi @MrEinstin,

You can find the schematic in kicad/parasite.pdf.

As for adding a USB connector, I think it's a great idea and something that also crossed my mind, but I ended up not going for it. On one hand, the nRF52840 chip we use does offer a USB stack which we could use. For using that for programming, I believe we'd need a bootloader like Adafruit_nRF52_Bootloader. You'd still need a SWD programmer for burning it in first. It also adds a few hundred milliseconds to each run, chopping the battery life in ~half and/or requires a switch to toggle between boot modes, which adds a moving part to the board. I really wanted to keep things simple and as cheap as possible that we could deploy and leave it running for a long time, so I decided against it.

For development, I've been using one these pogo alligator clamps and I find it's super convenient to quickly hook it up and program/debug while testing.

[drewzarn]

@rbaron This is great, thank you! I just priced out 15 boards and it's just under $32 with assembly. JLCPCB is short of the SHTC3 as well at the moment.

[rbaron]

Awesome @drewzarn. Please keep us posted!

[xlfe]

These arrived from JLCPCB today

[drewzarn]

@xlfe Were you able to source the chips that JLCPCB was missing?

[Senbei123]

Nice project!!!

[xlfe]

Only on back order for the temp sensor. AliExpress had heaps of the E73s

…

On Sat, 29 May 2021, 12:11 am Drew, ***@***.***> wrote: @xlfe <https://github.com/xlfe> Were you able to source the chips that JLCPCB was missing? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#3 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAI7RO3GTKT43ZY6LXJKV2TTP6QC3ANCNFSM45B4B24Q> .

[bit-bat]

@rbaron Thank you for putting the wiki together! This will help me save 10s of hours.
I have a request though - could you add the nRF chip as well in the BOM & placement files for JLCPCB?

This can save us some pesky SMT soldering when the chip is back in stock (and until then it doesn't hurt). I am planning to order around 30 of these (multiple pots and garden) and soldering that many SMT chips by hand is not fun.

[rbaron]

Thanks @bit-bat. I will update the nRF chip LCSC part in the design. I can't wait for this chip shortage to be over 😰

[rbaron]

Hi @bit-bat,

I updated the BOM and pick-and-place files with the E73 module in 753e5d8.

Since we can't order the SMT assembly with this part yet, we need to pay extra attention to the order when it does become available. This part requires special attention for SMT assembly because the footprint is not super standard. In practice, it's very likely JLCPCB engineers will take a look and fix the position and orientation of this component if there's an obvious error, or they might refuse the order if the footprint doesn't match. In that case, we'll probably need to find a way to use their specific footprint for it (sort of available here for EasyEDA - not sure if it's possible to download it for KiCad).

I will keep an eye on it and put an order for a trial batch once the E73 module is available. I'll report back here. If you're the first one putting an order with the E73 module, just pay extra attention and things should be good.

[argupta23]

@rbaron
Thanks for your efforts around pulling this all together and sharing it with the community.
I am interested in ordering some as well.
I do have a couple questions

1. Does JLCPCB provide testing of the assembled product? Assuming they would need some of your firmware to do that
2. Can the firmware you have listed here be shared with JLCPCB?
   Please advise.

@bit-bat
While I understand the issue with chip shortages, based on the order you placed. can you please share some details around the total cost of each unit (complete with the pending parts cost)?

[rbaron]

Hi @argupta23,

I don't think JLCPCB offers such a service, but I may be wrong. I imagine big fabrication houses might do that for really big orders, but I don't have experience with that. For the orders I placed there, I soldered, programmed and tested the boards myself.

[argupta23]

@rbaron
Appreciate the feedback. given the shortages on SHTC3 and the NRF modules, I will anyway end up in the same situation.
With regards to other discussions ongoing in different threads on possible alternatives, are you planning to make any changes to the current version of the PCB? If yes, can you share when will it be available and what would the updated parts list look like?

Please advise.

[rbaron]

@argupta23, I think a good plan is to update the slightly older and cheaper SHTC3 with some other Sensirion SHT*. I will update the design, do a trial batch and update the code accordingly.

For the nRF module, I am not so sure yet it's worth changing the design. Even though JLCPCB doesn't have it in stock, I've been getting them from aliexpress and I still see them listed for ~5-6 USD, which is okay given the circumstances. This wiki from nrfmicro lists some alternative modules, but I think they're all in a similar situation. I love the nRF52840, but it's a lot beefier than we need. Another possibility is to dial back and use something less powerful and cheaper, but that would incur considerable design and code change, and it's also not clear what the short term availability of that would be. We'd also lose the possibility of exploring ZigBee and on-chip USB for saving ~2 USD per board. At hobbyist's volumes, I don't think that pays off.

So, all that is to say that currently, on my mind, I think it's worth updating the SHTC3 and sourcing the nRF module separately.

[argupta23]

@rbaron
thanks for the feedback. I will go down the path of ordering the parts separately and put some builds together when I get them.

[bit-bat]

@bit-bat
While I understand the issue with chip shortages, based on the order you placed. can you please share some details around the total cost of each unit (complete with the pending parts cost)?

Hi @argupta23. I did not place the order as I am waiting for the chips to be available. Soldering 50 SMTs with ~30 pads each is a lot of work that I am not ready to commit (yet). But I did walk through the steps and at the end the PCB (with most components) was under $1 / unit when placing order for 50 units. This price doesn't include 2 chips - SHTC3 and nRF

[argupta23]

@rbaron
Is there a way I can reachout to you directly?
Thanks

[Tirocinante01]

hello I'm sorry to bother
I read the discussion and saw all the links and blueprints but I was wondering
is there any way I could get a few b-parasite already built and soldered?

i sadly have no experience on doing this stuff and I dunno any closely company that could print/build these out for me
im not looking for big numbers but just 3-4 for a project of mine
I tried looking around but found no websites where to buy some

[semperstew]

Please forgive my ignorance if this has been discussed elsewhere. I'm trying to follow your instructions in the wiki for ordering the PCBs from JLCPCB. After uploading the zipped gerber files, I am unable to add the order to cart because the specification is missing "dimensions". I had thought those would be somewhere in the gerber files. Do you have a default set of dimensions that you would recommend?

[rbaron]

Hi @semperstew,

I believe this field has been automatically filled every time I put an order with them, just after the zip file has been uploaded.

Would you try again and let us know if that worked?

[semperstew]

@rbaron I created a fresh clone and tried again. Seemed to work much better this time. A lot more of the data was filled in on the JLCPCB order form. Sorry about the false alarm.

Thank you for your tremendous work on this project.

[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.