Use lambda or variable in sensor configuration

Protoncek · August 3, 2024, 6:27pm

I’m playing with SHT31 sensor, and since it has heater i’m looking the way to temporarily enable it.
So, i wonder… is it possible to use lambda or variable (or anything except true or false) in sensor configuration variables? I mean - for my case i’d like to enable heater for, say, 5 or 10 minutes when i power-up esp module, then heater would be disabled the whole time until next power cycle. Is it possible to define something like:

heater_enabled: id(heater)

then define “heater” variable to “true” at start and change it to “false” after set time;

or something with lambda ?

heater_enabled: lambda.....

Note that it would also be a good idea to disable temperature and humidity readings during heating, so a second question would be: can i temporarily disable sensor in esphome?

Karosm · August 3, 2024, 7:52pm

What are you trying to accomplish? Why you want turn heater on for xx minutes?

walberjunior · August 3, 2024, 8:32pm

You can do an automation at boot.
But what other parameter are you going to check?
What if something happens and the device restarts?
Your heater may stay on for longer than you think

Why not a template switch?

Why?

Protoncek · August 4, 2024, 6:36am

Why? I would like to dry the sensor every now and then to ensure correct readings. In high humidity environments sensor can become moist, so humidity results will be wrong.
Ok, agreed, it can happen that device restarts suddenly, but i don’t think that heating for a bit longer would hurt. But, then again, i guess i could make things based on time (say, at midnight) , or manually, so that i’d create a binary sensor and i would enable it from HA, i guess. But, sadly i don’t know how to do any of these things…
Disabling measuring during heating is a good idea because while heating temperature measurements will be wrong (higher). There is also a warnign in datasheet about this.

What i don’t know how to do is enable that variable inside esphome yaml - or write anything there without error… I tried some things with “heater_enabled:”, but i always get an error that boolean is expected (true or false). I’m not that experienced in yaml (or lambda’s), so an example would be very welcome.

walberjunior · August 4, 2024, 1:49pm

Sorry, I completely misunderstood your post.

From what I saw, the option to turn the heater on or off is only executed at boot, line 41.

github.com

esphome/esphome/blob/61c65811233eb1b678fcfa077d6370e7f07ba091/esphome/components/sht3xd/sht3xd.cpp

#include "sht3xd.h"
#include "esphome/core/log.h"

namespace esphome {
namespace sht3xd {

static const char *const TAG = "sht3xd";

// https://sensirion.com/media/documents/E5762713/63D103C2/Sensirion_electronic_identification_code_SHT3x.pdf
// indicates two possible read serial number registers either with clock stretching enabled or disabled.
// Other SHT3XD_COMMAND registers use the clock stretching disabled register.
// To ensure compatibility, reading serial number using the register with clock stretching register enabled
// (used originally in this component) is tried first and if that fails the alternate register address
// with clock stretching disabled is read.

static const uint16_t SHT3XD_COMMAND_READ_SERIAL_NUMBER_CLOCK_STRETCHING = 0x3780;
static const uint16_t SHT3XD_COMMAND_READ_SERIAL_NUMBER = 0x3682;

static const uint16_t SHT3XD_COMMAND_READ_STATUS = 0xF32D;
static const uint16_t SHT3XD_COMMAND_CLEAR_STATUS = 0x3041;

This file has been truncated. show original

I think the best option is for you to create a PR on github to add a switch to control the heater.

github.com/esphome/issues

SHT3X-D needs to report and control heater status

opened 07:36AM - 14 Sep 20 UTC

closed 06:25PM - 24 Sep 21 UTC

Drizzt321

stale

**Operating environment/Installation (Hass.io/Docker/pip/etc.):**  Hass.io Home-Assistant, 0.114.4 from the QCOW VM image, ESPHome 1.14.4 from HA Integrations. **ESP (ESP32/ESP8266, Board/Sonoff):**  ESP8266, Wemos D1 mini **ESPHome version (latest production, beta, dev branch)**  ESPHome 1.14.4 from HA Integrations **Affected component:**  SHT3X-D temperature/humidity i2c sensor https://esphome.io/components/sensor/sht3xd.html **Description of problem:** So I got some cheap SHT31-D boards from Amazon, and they are reporting temperatures quite a bit above what I would expect from other thermometers I have. I've also compared using a Adafruit SHT31-D board + Arduino with their sample code, with the heater off. Looks like the cheap ones I got start off with the heater on. Since ESPHome code doesn't turn it off to start with, it reports significantly higher temps than it should. For example, the Adafruit Huzzah with these cheapo SHT31-D is reporting ~76F and ~57% humidity, one of the D1 mini with the Adafruit SHT31-D and ESPHome is reporting ~76F and 57% humidity. A separate D1 mini with the cheapo SHT31-D is reporting ~84F and 45% humidity. This SHT31-D is fresh, hasn't been set to be heater off via the Arduino code, so I presume the default is heater set to on. I think the SHT3X-D code should expose the Heater status (On/Off), and provide a control to turn the heater on and off. This lets HA script on/off the heater in a controlled fashion to evaporate/help remove condensation that may build up. **Problem-relevant YAML-configuration entries:** ```yaml i2c: sda: 4 scl: 5 scan: True id: bus_a sensor: - platform: sht3xd temperature: name: "Kitchen Room Temperature" humidity: name: "Kitchen Room Humidity" address: 0x44 update_interval: 60s ``` **Logs (if applicable):**  ``` PASTE DEBUG LOG HERE ``` **Additional information and things you've tried:**

Protoncek · August 4, 2024, 2:35pm

Thanks for explantion. In this case perhaps it’s better to replace sht31 with sht4x series, where heater can be enabled and then it’s turned on at regular intervals. I just have a couple of these sensors lying around. But, i guess i’ll just use them “as is”.

Karosm · August 4, 2024, 3:13pm

Sht4x was designed for that, by Sensirion the heater in SHT3x is “for plausibility checks only”. There is no documentation, that it could be used to remove condensation.