Author Topic: WeatherShield!  (Read 32555 times)

A

  • Newbie
  • *
  • Posts: 43
Re: WeatherShield!
« Reply #30 on: February 16, 2014, 06:53:28 PM »
I got my order of rev1 boards in the mail and built one up. I've already got a couple of assembly/cosmetic things I'm going to change on the board for a revision 3 (pad size on the ds18b20 and DHT22 being most notable). But I think I'll wait for the r2 boards to come in to see if there are any more changes I want to make before ordering/publishing it.

Thanks for all of the feedback so far, keep it coming!


DeKay

  • Newbie
  • *
  • Posts: 10
    • Mad Scientist Labs
Re: WeatherShield!
« Reply #31 on: February 17, 2014, 12:15:04 PM »
I've finally completed my latest blog post that discusses how I use my Moteino to pick up wireless transmissions from my Davis hardware in the front yard, combine that with a couple sensors hooked up to the Moteino itself, and then emulate the Davis indoor console well enough that it works with Sandaysoft's Cumulus weather software.  Check it out if you are interested.


kobuki

  • Sr. Member
  • ****
  • Posts: 287
Re: WeatherShield!
« Reply #32 on: February 17, 2014, 05:43:17 PM »
I got my order of rev1 boards in the mail and built one up. I've already got a couple of assembly/cosmetic things I'm going to change on the board for a revision 3 (pad size on the ds18b20 and DHT22 being most notable). But I think I'll wait for the r2 boards to come in to see if there are any more changes I want to make before ordering/publishing it.

Thanks for all of the feedback so far, keep it coming!

Nice design! I'm in the middle of a project with a Davis weather station (inspired by the great work of DeKay) and the indoor sensors are going to be something similar to your design which actually has many similarities to the EmonTH, which is part of the Open Energy Monitor project, and I originally planned to buy that. Now I'm undecided :)

I'd like to have a few suggestions:

- IIRC the DHT22 contains a DS18B20/DS18S20 sensor for temperature measurements, so including another one as a discrete part is probably not necessary (the RH sensor needs a temp. sensor for linearity compensation)
- I'd also suggest looking at supporting another sensor, the Sensirion SHT11, which is used in the aforementioned Davis station, and said to be more accurate than the DHT22, also easily available and frequently can be obtained for a bargain on Ebay

A

  • Newbie
  • *
  • Posts: 43
Re: WeatherShield!
« Reply #33 on: February 17, 2014, 09:09:34 PM »
Nice design!

Thanks!

- IIRC the DHT22 contains a DS18B20/DS18S20 sensor for temperature measurements, so including another one as a discrete part is probably not necessary (the RH sensor needs a temp. sensor for linearity compensation)

While it does have a temperature sensor, it is not a DS18x20. The temperature resolution and accuracy are not as good as a DS18B20 and lacks a serial number. However my idea with the board is to let folks order them from oshpark and populate only what they want, so if the accuracy from a DHT22/DHT11 is good enough for your needs then you can save a couple of bucks by not populating all of the parts.

- I'd also suggest looking at supporting another sensor, the Sensirion SHT11, which is used in the aforementioned Davis station, and said to be more accurate than the DHT22, also easily available and frequently can be obtained for a bargain on Ebay

The datasheet for the SHT1x says that it can share a bus with i2c, though you'll have to swap protocols. Not sure how well this would work with the i2c code folks are using. Otherwise Felix's power shield (http://farm3.staticflickr.com/2830/11145098386_74c8cd41e9_o.jpg) would be a good option for a Moteino with a single SHT11 breakout board once he releases it.

KanyonKris

  • Full Member
  • ***
  • Posts: 113
Re: WeatherShield!
« Reply #34 on: February 18, 2014, 01:52:02 AM »
DeKay, wow, you dig deep. Some fine hacking to get a Moteino to receive the data from your Davis weather station. I'm tempted to get one just to see your hard work operate, but alas I've got too many projects as it is. Still, I admire what you accomplished.

DeKay

  • Newbie
  • *
  • Posts: 10
    • Mad Scientist Labs
Re: WeatherShield!
« Reply #35 on: February 18, 2014, 07:47:24 PM »
DeKay, wow, you dig deep. Some fine hacking to get a Moteino to receive the data from your Davis weather station. I'm tempted to get one just to see your hard work operate, but alas I've got too many projects as it is. Still, I admire what you accomplished.

Thanks KK!  The Davis stuff is pretty good, and you can buy it at a substanital discount if you go through places like Archer Trading Post.  I think you can also buy just, say, the outdoor unit from them to get your foot in the door.  But the console, as old and crunchy as it is, is really nice to have.  First thing we do when waking up in the morning is check it to see how heavy a winter jacket we need to put on!

A

  • Newbie
  • *
  • Posts: 43
Re: WeatherShield!
« Reply #36 on: February 25, 2014, 09:14:15 PM »
I built an R2 board over the weekend, here are some photos:




Please excuse the potato quality photos and the less than spectacular SMD soldering, I didn't bother with a stencil since I've already got changes planned.

As you can see in the first photo, the pads for the DHT22 & DS18x20 are smaller than ideal. The other issue that a friend pointed out is that I haven't added any way to power down the external sensors. The 1-wire devices have a small enough idle drain, but the DHT22 and the BMP180 (if I can ever source any) are sucking down way to much for long term battery power.

I'm thinking of using a mosfet off of D3 to turn on and off all of the non-1-wire sensors. Anyone see an issue with this? I might even add in a second fet in the style of http://jeelabs.org/2013/05/18/zero-power-measurement-part-2/ to rework the battery sensor pin.

Felix, and anyone else who wants to chime in, do you have a preferred SMD mosfet? It looks like p-channel is ideal for the battery voltage sensing, but I am more flexible for the sensor power.

pko

  • Newbie
  • *
  • Posts: 12
Re: WeatherShield!
« Reply #37 on: February 25, 2014, 11:44:37 PM »
D3 is also tied to INT1.  So I suggest you start from D4 and up and only use D3 if you run out of pin.  This will reserve the Interrupt pin for future use without the hassle of reassigning the pin.

A

  • Newbie
  • *
  • Posts: 43
Re: WeatherShield!
« Reply #38 on: February 26, 2014, 01:08:52 AM »
D3 is also tied to INT1.  So I suggest you start from D4 and up and only use D3 if you run out of pin.  This will reserve the Interrupt pin for future use without the hassle of reassigning the pin.

D3 is the last pin that isn't being used by something onboard or the garagemote and I'd like to be able to stack a weathershield and a garagemote to get data in my garage. Though now that I'm typing this up, I will have wall power in my garage. Alright, D4 with the ability to not have the aux-power fet and bypass it so that the sensors are always on.

A

  • Newbie
  • *
  • Posts: 43
Re: WeatherShield!
« Reply #39 on: March 01, 2014, 11:33:37 PM »
Rather than adding in a transistor to turn on and off the DHT22, I added in a footprint for a very low power humidity/temp sensor, the Si7021. I've done my best to follow the design guide and put it on a semi-isolated island of PCB, but OSHPark doesn't guarantee cutouts, so it is a bit of an adventure. It has the same footprint and a the same basic i2c command set as the HTU21D which can be purchased on a breakout board from Sparkfun if anyone wants to try one out. The price for the sensor from Mouser is only $4.27, much better than the ~$10 for the DHT22.

I also added in a 3.5mm screw terminal for power, with a solder blob selector to go between using VIN and connecting directly into the 3.3V line, bypassing the voltage regulator (useful for AA battery power from what I understand.) Another addition is a second method for measuring VIN voltage, this time using a design from JeeLabs. Though I didn't have room for a through hole mosfet without increasing the board footprint, so if you're not keen on surface mount, you'll have to stick with the always on voltage divider.



A

  • Newbie
  • *
  • Posts: 43
Re: WeatherShield!
« Reply #40 on: March 14, 2014, 12:26:13 AM »
I've just built a couple of these, and everything seems to be working great. At this point the only thing I'd change is the screw terminal type up a size from 2.54mm to 3.5mm pitch.



I've set the project on OSHPark to public, pricing is currently "$13.45 per set of three."

I'm still working on combining all of the different sensor code blocks together, once I'm happy with that I'll toss it up somewhere.

Felix

  • Administrator
  • Hero Member
  • *****
  • Posts: 5938
  • Country: us
    • LowPowerLab
Re: WeatherShield!
« Reply #41 on: March 14, 2014, 07:22:17 AM »
That's really nice outcome, thanks for sharing this project!

V00d00blues

  • Newbie
  • *
  • Posts: 2
Re: WeatherShield!
« Reply #42 on: April 15, 2014, 11:09:39 AM »
Hello, I'm new around here, but I've been lurking for a while now.  What I was wondering is if you could post up the board file for your Weathershield? I'm interested in ordering/building one, but I'd need to get a stencil done up from Oshstencils before I would even begin to attempt to solder any of the SMT devices. 

Thanks!

Andy

A

  • Newbie
  • *
  • Posts: 43
Re: WeatherShield!
« Reply #43 on: April 15, 2014, 01:05:41 PM »
What I was wondering is if you could post up the board file for your Weathershield?

Hit the download button at the bottom of the OSH Park page to download the .brd that I uploaded.

V00d00blues

  • Newbie
  • *
  • Posts: 2
Re: WeatherShield!
« Reply #44 on: April 16, 2014, 01:02:49 AM »
Thanks a bunch!

Andy