2 - dramatic revision of the design of the greenhouse Pi HAT
4 My plan is to deploy two of these, one in each greenhouse, perched on Pine64
5 boards which have a Pi header.
7 The current design supports
9 4 one-wire temperature sensors with screw terminals
10 - at minimum, want an outdoor temp and inside temp on each
11 greenhouse. could be interesting to measure different
12 places in greenhouse, or slab temp in new greenhouse?
14 4 solid state relay outputs with screw terminals
15 - could be used for environment controls or whatever, not
16 used in our current greenhouses since heat and vent are
17 run by "dumb" thermostats
19 2 clip-on AC current sensors with 1/8" stereo jacks
20 - the point of these is to be able to see when heat and vent
21 are active, and indirectly to see what it's costing us to
23 - one side is biased to 1/2 VCC, the other side is
24 connected to ADC input. measurements will require sampling
25 at least one half-cycle of 60 Hz to get height of AC voltage
26 peak. sensors bought output 1V is 30A.
28 on-board MS8607 for temperature, pressure, and humidity
29 - this sensor does not want to be in direct sunlight
31 on-board photocell for light level
32 - if the board is packaged, this sensor needs to "see light"
34 on-board eeprom for HAT identification
35 - will load the parts, not sure if I really care if it works
36 or not, but this would allow auto-detection by kernel and
37 loading of appropriate drivers?
40 - Karen asks about adding rain gauge support
42 RainWise makes a wired "tipping bucket" rain gauge, the "RAINEW 111", that
43 sells for $72.95 and comes with 60' cable and a little display. Clams to
44 meet NWS accuracy specs, and measure 0.01" per bucket tip.
46 Doing a little web searching turned up this article on hooking one to a
47 weather station design from Slovakia:
49 https://www.baranidesign.com/faq-articles/2019/9/3/how-to-connect-rainwise-rain-gauges-to-meteohelix-personal-weather-stations
51 The gist is that they say the cable from the sensor is 2 wires and provides
52 a normally open switch contact that pulses once per "tip". They also assert
53 this is a common interface.
55 So, to read this, we'd want to have another GPIO input with a pull-up
56 resistor. Might as well support two such on a 4-screw strip since I have