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DS18x20 temperature sensor~

This feature is included in tasmota, tasmota32, tasmota-knx and tasmota-display binaries

When compiling your build add the following to user_config_override.h:

#ifndef USE_DS18x20
#define USE_DS18x20               // Add support for DS18x20 sensors with id sort, single scan and read retry (+2k6 code)
//  #define W1_PARASITE_POWER     // Optimize for parasite powered sensors
#endif

DS18x20 driver supports DS18B20, DS18S20, DS1822 and MAX31850 1-Wire digital temperature sensors.

Configuration~

Wiring~

DS18b20 ESP
1 GND GND
2 Data GPIOx
3 VCC 3.3v

Warning: DS18x20 will not work on GPIO16

You need to connect a 4.7K pullup resistor from data to 3.3V.
Wiring

Tasmota Settings~

In the Configuration -> Configure Module page assign:

GPIOx to DS18x20

After a reboot the driver will display Temperature.

Shelly 1 Temperature Addon~

Shelly dual pin mode is supported by an additional pin assignment:

  • GPIOy to DS18x20-o

Commands~

SetOption74 may be used to enable/disable internal pullup when using a single DS18x20 sensor (for multiple sensors, you have to use an external pullup resistor).

SetOption126 Enable arithmetic mean over teleperiod for JSON temperature for DS18x20 sensors.

TempRes Temperature sensor resolution: 0..3 = maximum number of decimal places.

TempOffset can be used to add/sub an offset to the measured temperature. This setting affects all temperature sensors on the device.

Multiple Sensors~

Tasmota supports multiple DS18x20 sensors connected to a single ESP8266/ESP32 chip using a single or multiple (up to 4) GPIOs. The default maximum is set to 8 sensors (driver code). It is possible to override this number in user_config_override.h by adding a line with #define DS18X20_MAX_SENSORS <new-value> (ESP8266/ESP32 only). However one should take into account that:

  • Display on the console is limited and SENSOR log will be truncated above 11 DS18x20.
  • MQTT buffer length is limited and SENSOR message will be truncated above 18 DS18x20.
  • Even less if other sensors are attached to the ESP device and present in the SENSOR message.
  • 1-wire has been designed to be a board-bus, not to run through long distances across a whole house. At minimum, use a shielded cable.

Note

If you increase the value above default, you are on your own. No support will be provided.

multiple wiring

Every sensors will get a unique ID used in webUI and MQTT telemetry.

{"Time":"2021-01-02T09:09:44","DS18B20-1":{"Id":"00000566CC39","Temperature":13.3},"DS18B20-2":{"Id":"0000059352D4","Temperature":1.2},"DS18B20-3":{"Id":"000005937C90","Temperature":22.5},"TempUnit":"C"}

Sensor Aliases~

By default, sensors are named using the <sensor model>-<n> scheme (e.g. DS18B20-1), where the number is practically random (based on the sensor's address). This means when you add or remove a sensor, the numbers of the sensors change.

To assign static alias to a certain ID, you can use DS18Alias command which can be enabled by setting #define DS18x20_USE_ID_ALIAS in user_config_override.h and compiling your own binary.

Then you can run DS18Alias, which returns full IDs of all the connected sensors and set a static index by using DS18Alias <sensor ID>,<n> command, for example DS18Alias 113C01F096174528,2. This will rename the sensors to the DS18Sens-<n> scheme, leading to the following output of the DS18Alias command:

{"DS18Sens-2":{"Id":"113C01F096174528"},"DS18Sens-1":{"Id":"783C01F096F2BB28"},"DS18Sens-3":{"Id":"8B0316C310F3FF28"}}

This is not persistent across reboots, therefore you should add a System#Boot rule (or autoexec.bat) so that your aliases are set again after each boot. For example:

Rule1 ON System#Boot DO
Backlog DS18Alias 783C01F096F2BB28,1;
DS18Alias 113C01F096174528,2;
DS18Alias 8B0316C310F3FF28,3
ENDON

To remove the alias and revert to the default naming, use 0 as the number index DS18Alias <sensor ID>,0, for example DS18Alias 113C01F096174528,0.

Compile Options~

There are some compile options (driver code):

USE_DS18x20_RECONFIGURE: When sensor is lost keep retrying or re-configure
DS18x20_USE_ID_AS_NAME: Use last 3 bytes for naming of sensors
DS18x20_USE_ID_ALIAS: Enable DS18Alias command (see above)

Sensor Versions~

Sensor variations

Pinout when looking at the flat side of the TO-92 package sensor: GND, Signal, VDD. Pinout of the wired sensor: black: GND; yellow or white: Signal, red: VDD

THR316D/THR320D Wiring Notes~

4P4C RJ9/RJ10/RJ22

4P4C RJ9/RJ10/RJ22 ESP DS18b20
1 (Yellow on image) 3V3 GPIO27 providing 3V3 Red on wired sensor
2 (Green on image) GPIO25 data Yellow or White on wired sensor
3 (Red on image) NC
4 (Black on image) GND Black on wired sensor

You do not need to add a pull-up resistor (The THR316D/THR320D has it built in.)

ESP-01 Wiring Notes~

Danger

BEWARE OF MANY VISUALLY SIMILAR BOARDS TO THIS RELAY BOARD but different schematics

ESP-01S

Some modules have culprits: * "CH_PD" is not set to HI (3.3V) as actually required. Usually this is done with a 10K resistor or directly to 3.3V, I have connected directly to the 3.3V * A resistor (R2 10k) which is connected between the terminal GPIO0 to ground. This ensures that the GPIO0 is always pulled to ground, which actually places the ESP-01 in program mode (flashing). To make the module working it is necessary to remove (solder out).

Connect DS18B20 to the GPIO2 (see diagram below - soldering not necessary, it is possible to put the wires and the resistor directly in to the female part of the connector together with ESP 01S module pins)

After flashing, set up Tasmota (see images below): * "Generic module" * GPIO0 as Relay 1 * GPIO2 as DS18x20

Rule Triggers~

The following trigger events are supported for use in Rules:

Single sensor attached:

  ON DS1820#Temperature DO <command> ENDON
Multiple sensors attached:
  ON DS1820_1#Temperature DO <command> ENDON
  ON DS1820_2#Temperature DO <command> ENDON
  ON DS1820_3#Temperature DO <command> ENDON
  ON DS1820_..#Temperature DO <command> ENDON
Example:
 ON DS1820_1#Temperature!=%Var1% DO backlog publish espTempertature/sensor/DS1820_1/data %value%; Var1 %value% ENDON