Components Selected and Sensor Ponderings

A project log for Weather Station Featherwing

Measure and log ambient Temperature, Humidity, Pressure, Light, Lightning, and Volatile Gasses with a Feather!

sirmylesaverysirmylesavery 12/03/2019 at 01:463 Comments

The BOM for Rev1 of the Weatherstation is available here from Octopart. As some comments on this project have noted, the CCS811 sensor may be redundant, since there is the BME680 sensor. Any input from others is greatly appreciated.

I should probably also mention that this board is currently just in the design phase. No boards have been actually ordered/built nor have any of the components been tested together. All of the sensors have been used in the past on their own breakout/dev boards and have prebuilt libraries for Arduino, so I have fewer concerns about it functioning if designed properly. Unfortunately I do not own any of the components needed to test this. I am currently in school and crunching for the last two weeks, so there will be limited work done on this. Hopefully I have the time/energy/money to either assemble the appropriate breakout boards to test this assembly or order and built this board.


bobgreenwade wrote 12/06/2019 at 15:49 point

Nice job working all of this in at a good price! This board does (or, rather, will do) a lot for $37.60, even considering that that doesn't include the PCB and labor!

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sirmylesavery wrote 12/06/2019 at 21:56 point

Ya, I was initially surprised by how cheap it would be components wise. Unfortunately I just realized that I didn't have right number of certain components!! With the proper number of components, the BOM is now $39.16, which is not terribly more expensive, but unfortunate.

That $39.16 is with components only from DigiKey, but doesn't include shipping. Unfortunately DigiKey only has 92% coverage of the BOM, because there is one component, the lightning detector antenna, that is only available from Mouser or the manufacturer, Coilcraft ( I typically choose my components to only be from one distributor to minimize shipping costs. I typically go with DigiKey because I am most familiar with it as a distributor. If you have any others you would recommend, please feel free to let me know!

If you do a mixture of Mouser and DigiKey for 100% BOM coverage, cost for only components goes down to $38.00, but there would be two shipping costs. 

If I were to remove the CCS811 sensor it would reduce the price by -$12.88 or -$11.30, depending on if you get the sensor from DigiKey or Mouser respectively. I'm leaning towards removing this sensor given the little research I have done when comparing it to the BME680. The combined distributor price without the CCS811 sensor would be $26.70, which is significantly cheaper! This price (after compensation for shipping, assembly, profit, etc.) is probably comparable to the SparkFun Weather Shield, which costs $39.95, especially since my board includes a lightning detector and microSD card holder, which the SparkFun board does not. Unlike the SparkFun board, my board does not currently support expansion for windspeed, rain gauge, and GPS sensors. But maybe at some point in the future!

Thanks for the comment which allowed me to catch the quantity error!

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bobgreenwade wrote 12/06/2019 at 22:34 point

However it works out, it's still pretty good to keep it under $40. I've been trying to design a board of miscellaneous sensors (for private use in a robot companion), including specific common but hazardous gases, and... well, let's just say that those sensors are considerably more expensive than the general gas sensors. (I may try adding the lightning sensor, though, just for funzies.)

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