From the Lab ...

... Hacking and Slashing since 2002

So I decided I needed a little more data regarding how much current the RPi used at various points in time, and with various peripherals attached. So without further delay ... 
 
Test setup: Tektronix TM5006 with PS5010 & DM5110, RPi zero W; 32GB class 10 card; wifi on; VNC on; with and without Apple keyboard and mouse; with and without external LCD monitor; with and without camera module hooked up and/or turned on; and/ or streaming video. 
 
1) During boot, no external peripherals, wifi on: ~250mA (peak) 
2) During boot, with keyboard & mouse, wifi on, monitor attached: ~450mA (peak) 
3) During boot, camera module attached, wifi on: ~ 250mA (peak) (no discernible increase from attached camera) 
 
4) Steady State, no external peripherals, wifi on: ~115mA (peak) (typical average also) 
5) Steady State, with keyboard & mouse, wifi on: ~280mA (peak), with mouse movement: ~360mA (peak) 
6) Steady State, with keyboard & mouse, wifi on, monitor attached: ~290mA (peak), with mouse movement: ~385mA (peak) 
7) Steady State, camera module attached, wifi on: ~115mA (peak - no streaming), streaming video: ~ 360mA 
 
#7 is the key for me ... I plan on having wireless cameras around the chicken and duck coops, and the garden, and the yard. The original plan was to use solar to charge Lion battery packs ... but ... I might need a little more power for during the evenings and stretches of cloudy days. A typical 18650 cell has about 2500mAhr of current capacity. So at 360mA (worst case streaming constantly), that gives me about 5.15 hours (when converting from 3.7v to 5v at very high eff.)  

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So I received this plant monitor from China recently, and finally had a chance to play with it / tear it down. I would be remiss if I didn't state my disappointment with having to register an email address (un/pw) for usage / access to the iOS app. Suffice it to say but it was a burner address. 
 
More details to come... 
 
Pics: 
 
In the package. 
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It's a little hard to make out, but I see no FCC ID's nor any Bluetooth Sig ID's. 
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Front. 
IMG_5504.JPG 
 
Rear. 
IMG_5505.JPG 
 
Battery cover removed. 
IMG_5506.JPG 
 
Top side of board ... They use a Dialog DA14580 (cortex m0) for BTLE comms. PCB-trace IFA antenna is in upper right quad. Very top is a simple photodiode for light measurement. 
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Bottom side (with battery holder). 
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Closer shot of the Dialong BTLE part. 
 
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Not sure, but I suspect that this is an op-amp. I *think* they use it in the permittivity / dielectric measurement of the water content of the soil. It does NOT appear to be used in the Ion conduction (conductivity) measurement. 
 
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And I recently received my Time Domain Reflectometry (aka TDR) Probe. I have been dipping my toe into the Urban Ag / Open Ag scene over the past couple of years, but this year I'm diving in to the deep end. The is partly out of engineering curiosity and partly out of necessity. 
 
The curiosity part is applying my multidisciplinary engineering background to develop a small scale / robust / wireless sensing network for a large-ish urban farm (see https://www.facebook.com/3acresandabarn/). Ultimately I want to sense what's going on in the earth. Anything and everything that I can sense. 
 
The necessity part is longer term. Kelly and I plan to be here (where we live) for a long time. As we see it, two thing are definitely going to happen. 1 - Energy prices are going to increase (hence the Solar Projects going on at the urban farm - I'll explain fully later). And 2 - Food pricing is only going higher, and supply is only getting tighter. I suppose a third reason is related to the 2nd ... knowing where and how some of my food was grown. 
 
For those that see this in time, there is an OpenAg open house at TechShop in St. Louis on 2/2/17. I'll be there. 
 
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Finally received my Nordic PPK. I've only used this a little bit, but so far it's a fantastic tool for measuring the current consumption of Nordic parts / boards / modules. 
 
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Last year I decided that I needed a better (easier / lazier?) way to control watering around the farmstead. Did I ever mention that we have an Urban Farm? See here ... https://www.facebook.com/3acresandabarn/ 
 
Back to our regular program ... So I purchased a couple of inexpensive Orbit water valves with timers, and did what any self-respecting engineer would do ... I gutted them! Seriously though, I removed the Cypress MCU that was on the board and swapped in an nRF51822 BLE part (via an rfDuino RFD22301 module). After al little coding on both the Nordic part and a complimentary iOS app, I had a remotely controllable water valve. Sweetness. 
 
This year (2017) I plan to go all out with the Farm-tronics stuff. I have a camera setup ready to go for the chicken coop (RPi and camera), and several soil sensors ready to go into our various garden beds. Not 100% sure how all of this will come together in the end, so stay tuned. We'll use these water valve for some drip / soaker applications to better control moisture in the beds. 
 
Pics... 
 
Front / outside... 
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Rear / outside... (dark gray portion is the battery holder ... 2AAs) 
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Inside (water valve on the right is a latching type so there isn't a constant high-level battery drain)... 
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Closeup of the RFD22301 module and my 4 pin programming port. I do not use DFU (partially on purpose), so I need a way to program parts in-circuit. This is how I do it... 
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