pihvac

Raspberry pi control of temperature and humidity by switiching AC, heat, humidifier, and dehumidifier

pihvac.py controls an AC, heater, humidifier, and dehumidifier to maintain a given temperature and RH. Currently the setpoints and tolerances are just hard-coded as constantas at the top of the file. It uses sht31.py to read temperature and RH from a SHT31 sensor attached to I2C and GIPO4.
sht31.py is a module providing the SHT31 class for reading temperature & RH sensors. It can deal with an arbitrary number of sensors attached to common I2C + one GPIO (select/enable) per sensor.
indoor_outdoor/read_sht31.py is a simple standalone script for reading SHT31 temperature & RH sensors on a Raspberry Pi. The chamber_control script for tracking a remote temperature calls runs this on a remote pi (via an ssh command) to get the current values. It is adjusted to work on an old Raspberry Pi V1, while sht31.py wants the newer version of python available on new models.

There are various other files from trying out various interfaces (bokeh and cgi/www) as well as other cruft.
Potentially of use is smartgadgetBLEread.py which reads data from a Sensitron SHT31 SmartGadget via bluetooth.

pihvac.py

Running automatically

On 10.200.59.159, pihvac is automatically started on boot and outputs a log to /home/pi/pihvac_autostart.log. To modify this behaviour, edit /etc/rc.local.

To change setting (setpoints, light times, ect.), edit /home/pi/pihvac.py and then restart the computer sudo restart now.

Running by hand

To run it in a session on the command line, you will normally want to login and run byobu, tmux, or screen before running this script so it doesn't stop when you logout or are disconnected. I prefer tmux (when you log back in you run tmux a to reattach to the session).

cd pihvac
./maildone.sh ./pihvac.py |& tee -a log0.log

replacing log0.log with whatever logfile you want. -a means to append to the logfile if it already exists.

Log output

nominal output are tab separated rows like:
2019-02-07T12:26:09.633537-10:00 24.96 24.50 70.46 70.00 False False False False True

Timestamp
Temperature last sensor read
Temperature setpoint
Relative humidity last sensor read
Relative humidity setpoint
AC is on?
Heat is on?
Humidifier is on?
Dehumidifier is on?
Light is on?

Hardware

SHT31 modules are connected to a Pi SMBUS using pins:

1 : 3v3
3 : SDA1 I2C
5 : SCL1 I2C
7* : GPIO4 (or any other GPIO) connected to the SHT31 addr pin Multiple SHT31 modules can share the same connections with the exception of this GPIO pin.
9 : Ground

The Pi in the insectary container has 6 GPIO and 2 Ground connections wired over to the powertails/relays. Those are pins 33 to 40: