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Homie Heat Pump

Yet another IR Library for HVAC related systems -- with a twist. The decoding of the display enables automated capture of the internal measurement characteristics of the unit. You get evaporator intake and coil temperatures, condensor intake and coil temperatures, compressor discharge temperatures, RPM/frequency of compressor, indoor, and outdoor fans, and also TXV angle amongst other measurements. There are a whole range of units spanning multiple brands that DO NOT have serial ports with this info. But, these units still have this info, here is how you get it online.

Yes, with these measurements, diagnostics of issues with the unit are as simple as looking at your thermostat. Also, only thing missing from calculating total efficiency of the unit in real time is a sensor on the current supply. There are other separate current sensor projects out there, someone is gonna put them together (please let me know if you do!)

NOTE: This is by no means a complete project. At best, it is fun experimentation only. If the ESP8266 crashes, the last run setting is saved and it is restored on reboot. Use on your equipment is entirely your responsibility. This library is currently being used on my heat pump unit BUT, it is still in the research phase. Use at your own risk. (Note: I've been able to plug and un-plug this board whilst the unit is on witout problems [pics: see wiki])

The project is GPL V2.0 which means I share, you share. Pull requests are welcome. For instance, I'd love to get more sample data to verify the undocumented measurements (You'll see what is currently known documented in the header file for SenvilleAURADisp.hpp). Especially for these reserved codes, there is likely to be some variation across brands so there is work in building up a matrix there.

To add your own brand/model of heat pump / AC unit, it is expected that you'd use IRHVACLink class directly, mess with parameters passed to it, then add your own new class, similar to SenvilleAURA class, to encapsulate the specifics of your model. The SenvilleAURADisp class is still in research mode and its applicability/extension for other models remains to be seen.

Check out the wiki for pics. of a test rig. https://github.com/kpishere/homie_heatPump/wiki

Overview

This library sports fully independent classes for physical layer communication and logical layer protocol of Send/Receive signals to/from a heat pump for the purposes of replacing the hand-held remote. There are Arduino *.ino test/example files of using the physical layer classes on their own. There are other test examples of using the physical+logical layers. There are also other examples of using Homie (link: https://github.com/marvinroger/homie-esp8266 ) library and framework for home automation, MQTT communication, OTA management, and WiFi configuration management.

Features

This library is independent of Homie, the example merely uses it and you'll have to check out the Homie project if you'd like to set up your development environment to use that too. This library is written for and tested on ESP8266 and Atmel Mega 2650 (and likely works for other Atmel chips .. haven't tested and you're welcome to test/patch etc.) It is written using interrupt driven events for reading data and an interrupt timer for sending data and thus is written to play nice with ESP8266 WiFi interrupt responsiveness demands.

New

A configuration for a generic NEC remote control has been added -- for something completely different from HVAC. With that, the send/receive pins can be split and are parameterized.

Wiring Suggestions

Specific to the Senville AURA brand of Heat Pump (this may also work for some Mr.Cool, Comfort-Aire Century, Danfoss, Pioneer, and Lennox heat pump models too as they all use the same remote controller and chip-set, Sino Wealth SH66P51A) there is also a class to replace the entire display board (you could fashion your own y-cable to keep the display but I intend to replace it with this project). Check out file SenvilleAURADisp.hpp for detail of the wiring connections. Note: If you are just looking for IR functionality, I recommend using CN301 rather than the documented CN101 connector. From the CN301 connector, you'll sense any other IR signal sent to the unit and you won't have to modulate the signal if you send on this connector -- this sending code is written for an un-modulated IR signal. Otherwise, with the CN101 connector, the receive line basically illuminates the infra-red LED that is on the board, right beside the receiving unit -- it is a cheap one-way optio-coupler! If you really want to use that connection then perhaps use another pin with a PWM of the carrier and an external switching transistor connected to the IR output pin controlled from this code.

Trust me, with this class of heat pump, there is no serial link here. I've searched deeply for it! (There is a programming header on the interior board but I just didn't want to go there. Other than that connector, the only serial link is between the interior and the exterior boards .. something else I didn't want to disturb.) To fully replace the display board with, for example, a NodeMcu demo board, you'd wire it as such :

CN201 --> NodeMcu

  • GND Black --> GND
  • 5V White --> 5V In
  • IR Red - IR pulse duration signal --> D1
  • DATA Orange - DATA for LEDs --> D7 (DATA_MOSI)
  • LED1 Green - LED1 select w. 12 ms waveform --> Not connected
  • LED2 Dk Blue - LED2 select w. 12 ms waveform --> Not connected
  • LED Purple - LED select w. 12 ms waveform -- > D2
  • CLK Grey - CLK w. 8-bit bursts of 10 us tick each 4 ms --> D5 (CLK_HSPI)

NOTE and NB! : ESP8266 is said to be 5V tolerant on sensing and will only drive pins to 3.3V but you may want to use some level converting circuitry here, just in case. I tested without level conversion but intend to use level conversion in the final project. The signals are all 'input' really. The IR signal is normally high and pulled low by the ESP8266. I'm merely adding for sake of possible surges or power on/off spikes.

Configuration

For configuring WiFI, create your own config.json file in your working project folder and use the bash script config.sh to upload the settings. It is more handy and straightforward than the clever (but still awkward) html config page presented in the homie project web pages.

Example:

{"name": "heatpump","wifi": {"ssid": "VeggiePlatter","password": "chicken"},"mqtt": {"host": "192.168.1.199","port": 1883,"auth": false},"ota": {"enabled": true},"device_id": "heatpump"}

Sending an instruction to turn on heatpump, set temp, and put in heat mode with auto fan from MQTT :

...: mosquitto_pub -h localhost -t homie/heatpump/heatpump/control/set -m "{IsOn:1, Instr:1, Mode:0, FanSpeed:0, SetTemp:22}"

Updates

There is a new target, sming_headpump (see: Sming) The other Arduino target examples remain, along with the Homie one but the net result is that Homie 2.0.0 with Arduino Lib v.2.4.2 was not reliable enough to use for HVAC. Even with the watchdog timer, after a day or two, it was not reliable. Future development (from me anyhow) will be tested only with Sming library and the xtensa build chain.

Upcoming

Will be continuing with monitoring data collection from operation of unit and with validated measurements, adding a property(ies) to the MQTT stream for these values. Progress on the display class and accessing properties has been made. To make this faster though, there was a pause in the project to add OTA update capability (was doing too much running from office to furnace!). This is very close to working.