custom device MQTT 'Ozone_PDMtimer' case study
This is a DIY specialized timer for Ozone generators for domestic sanitation, build starting from Sonoff S20 (power plug) or a Sonoff basic and the esp_MQTT firmware. The Sonoff switches are perfects, as price and form factors, for this application, and they are easy to use. The features of the timer are:
- PDM power control: 2%-100% to better control the Ozone production (see 'Strategies in the use of ozone' in Ozone-coronavirus-sonoff).
- Mode LOOP: for continuous cyclic use and low concentrations. Time ON 1min..6h, time OFF 1min..6h.
- Mode AUTO: only one cycle for chock sanitation, with a manual or remote or timed start. The manual start is delayed by 1 minute to allow the user to exit.
- Wifi: AP for the Wifi setup and for use without a router, STA for use with a router, OTA for the software update.
- The features of this timer are not easy implementable with a standard tuya switch, a custom solution is better.
This Ozone_PDMtimer has two interfaces (not using tuyaDEAMON):
- PC node-red interface, more complete: to guide the user, the UI enables or disables the controls according to the current state.
- Android smartphone, simpler and more standard, created using IoT MQTT Panel, see files.
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The original 'Ozone_PDMtimer' can be used: - **Standalone**: the timer is used alone, controlling it with its button. Portable, but the timer must be configured in advance. - **SoloAP**: The timer is configured as AP, the client (e.g. a smartphone) must have the WiFi connected directly to the timer AP. - **LanRouter** The timer is configured as STA and connects to the router's WiFi. The timer uses an NTP server to get the exact time. The details of the MQTT 'Ozone_PDMtimer' project can be found here: https://github.com/msillano/Ozone-coronavirus-sonoff/blob/master/PROJECTS-DIY/timerPDM/timerPDM_sonoff_en.pdf. |
Why integrate this MQTT Ozone_PDMtimer in tuyaDAEMON?
- With TRIGGERs, we can control the timer and get notifications from any distance.
- The DB data logging can enable statistical and commercial extensions.
- Automations can be build to do sanification in an automatic way (e.g. when the home is empty).
- It is a simple but good example of MQTT devices integration in tuyaDAEMON, easily reusable.
For the integration, I make a subflow that directly replaces the tuya-smart-device node, so this MQTT device is, for tuyaDAMON, a 'real' device. I used the 'dynamic retry' node because the timer and the ozone generator are often unplugged from the power outlet. "REFRESH" subflow is not required.
I defined the DPs, using tuyaDAEMON.toolkit and the same names used in MQTT, with few exceptions, so the implementation is a simple protocol change.
Because the Ozone_PDMtimer sends an _info message every second, I implemented refreshCycle inside the subflow, mostly to reduce the rate.
- MQTT-ozone-1.subflow.json : Import this subflow in node-red tuyaDAEMON to add the 'MQTT ozone PMtimer' device.
- IoT-MQTT-Panel.timerPDM#1.json : Import this file in IoT MQTT Panel (Android) to get the UI for Ozone_PDMdevice.
The original timer project was designed without thinking about the Tuya IoT model, but to simplify the UI and with the constraint of a limited amount of device memory, so the 'Ozone_PDMtimer' behavior is not standard: SET responds with many DPs but not all, SCHEMA is not implemented, etc.
Despite this, the conversion from/to MQTT is still simple and can be also simpler in new projects, if they more strictly follow Tuya's conventions. So this is a viable way to integrate many custom or third-party MQTT devices into the tuyaDAEMON system.
Update version, REFRESH implementation rewritten.
