Sensors

This page describes various sensors supported by ESPurna.

To enable particular sensor in firmware, you should build the firmware with appropriate build flags (-D) set to 1. The table below lists all supported build flags. Some sensors have additional options, so please check additional information below.

In most of the cases, just setting a build flag to 1 will do the trick - most sensors have default options for auto-detecting sensor parameters or using most widely used values. Still, you have full control, so feel free to customize.

For example, to enable DHT sensor support on GPIO14, you should set:

[env:your-board-name]
...
build_flags = ${common.build_flags_1m} -DDHT_SUPPORT=1 -DDHT_PIN=14
...

When setting GPIO assignments, be careful not to override any of the GPIO used for flash - this would normally render your board unresponsive and you would need to re-flash it using USB programmer, which is not always convenient.

Sensors

Common Sensors	Build flag
Analog sensors	ANALOG_SUPPORT
Generic digital sensor	DIGITAL_SUPPORT
I2C Bus	I2C_SUPPORT
Power Meter Sensors
Analog energy monitor	EMON_ANALOG_SUPPORT
ADC121 Energy monitor	EMON_ADC121_SUPPORT
ADS1x15 Energy monitor	EMON_ADS1X15_SUPPORT
ECH1560 based power sensor	ECH1560_SUPPORT
HLW8012 Energy monitor IC	HLW8012_SUPPORT
PZEM004T based power monitor	PZEM004T
V9261F based power sensor	V9261F_SUPPORT
Temperature and/or Humidity Sensors
BME280/BMP280 environmental sensor	BMX280_SUPPORT
Dallas 1-Wire sensors	DALLAS_SUPPORT
DHT environmental sensors	DHT_SUPPORT
SHT3X environmental sensor	SHT3X_I2C_SUPPORT
SI7021 environmental sensor	SI7021_SUPPORT
Air Quality Sensors
MHZ19 CO2 sensor	MHZ19_SUPPORT
Particle Monitor based on Plantower PMSX003	PMSX003_SUPPORT
Light Sensors
BH1750 Digital light sensor	BH1750_SUPPORT
Other
Counter sensor	EVENTS_SUPPORT

---

Analog sensors

This will enable support for Analog sensors, connected on ADC pin.

Option	Note
ADC_VCC_ENABLED={0,1}

---

Generic digital sensor

This will enable generic digital input sensor (switch or a pushbutton). Up to 8 inputs are supported. Replace x in these options with 1-8 to configure multiple inputs.

Option	Note
DIGITALx_PIN={0-15}	GPIO to use (default: 2)
DIGITALx_PIN_MODE	Initial GPIO status. One of: - INPUT_PULLUP (default) - INPUT
DIGITALx_DEFAULT_STATE	Default state on boot (default: 1 / on / high)

---

I2C Bus

Enable generic I2C bus support. It will be automatically enab;ed if any sensor that requires it is also enabled, but you might want to choose non-default ports.

Option	Note
I2C_SDA_PIN={0,16}	GPIO where SDA line is connected (default: 4)
I2C_SCL_PIN={0,16}	GPIO where SCL line is connected (default: 14)

---

BH1750 Digital light sensor

This enables support for digital light sensor based on BH1750, such as this one , or this one.

Datasheet for the sensor itself is here

Option	Note
BH1750_ADDRESS={0x00-0xFF}	I2C address of BH1750 sensor. Default 0x00 (auto)

Note: Will automatically enable I2C.

---

BME280/BMP280 environmental sensor

This will enable support for BME280 or BMP280 humidity, temperature and pressure sensors.

Option	Note
BMX280_ADDRESS={0x00-0xFF}	Default is 0x00 (auto)

Note: Will automatically enable I2C.

---

Dallas 1-Wire sensors

These are sensors like the DS18B20.

Option	Note
DALLAS_PIN={0-15}	GPIO where 1-Wire will be enabled

All sensors discovered on a 1-Wire bus will be reported.

Troubleshooting (thanks to @AlberWeterings):

As most of you know on aliexpress many cheap DS18B20 sensors are sold and a lot of them are (counterfeit) fake. I have got myself a lot of them. Having that said I will sum up some problems you might run into using these sensors on ESPURNA.

• A Sonoff TH10 has internally two 10K resistors in parallel from VCC 3v3 to IO pin 14 resulting in a 5K resistance. So if you use a genuine or fake sensor no 4K7 resistor is needed.
• If you connect a fake sensor for example to a Sonoff TH10 and you use a resistor of 4k7 from VCC to DO you will see the temperature rising over time this is due to the sensor heating up its self rapidly. The 4k7 resistor makes it worse.
• Most Fake sensors also heat up with the Sonoff's internal resistance of 5K
• Replacing the internal two 10K resistors with one 50K resistor stops the rapid heating up. but measurement is still inaccurate.
• If you have your fake DS18B20 mounted on a surface or floating in a fluid it will not heat up rapidly anymore but still is giving inaccurate measurements as it is heating its self internally.

I was unable to find a setup in which the fake sensors where measuring accurate so my advise if you ever have issues with these type of sensors compare it to a sensor that is known genuine.

---

DHT environmental sensors

Option	Note
DHT_PIN={0-15}	GPIO where DHT sensors are connected
DHT_TYPE=<type>	One of the: - DHT_CHIP_DHT11 - DHT_CHIP_DHT21 - DHT_CHIP_DHT22 (default)

---

ECH1560 based power sensor

Option	Note
ECH1560_CLK_PIN={0,15}	GPIO where ECH1560 CLK is connected (default: 4)
ECH1560_MISO_PIN={0,15}	GPIO where ECH1560 MISO is connected (default: 5)
ECH1560_INVERTED={0,1}	Is signal inverted (default: 0 - no)

---

ADC121 Energy monitor

Option	Note
EMON_ADC121_I2C_ADDRESS={0x00-0xFF}	I2C address of ADC121 sensor (default: 0x00 - auto)

Note: Will automatically enable I2C.

---

ADS1x15 Energy monitor

Option	Note
EMON_ADS1X15_I2C_ADDRESS={0x00-0xFF}	I2C address of ADS1x15 sensor (default: 0x00 - auto)

Note: Will automatically enable I2C.

---

Analog energy monitor

Energy Monitor based on interval analog GPIO.

Option	Note

---

Counter sensor

Option	Note
EVENTS_PIN={0,15}	GPIO to monitor for pulses (default: 2)
EVENTS_PIN_MODE	Initial GPIO status. One of: - INPUT_PULLUP - INPUT (default)
EVENTS_INTERRUPT_MODE	On which signal transition to react. One of: - RISING (default) - FALLING - BOTH

---

HLW8012 Energy monitor IC

Option	Note
HLW8012_SEL_PIN={0,15}	GPIO where SEL is connected (default: 5)
HLW8012_CF1_PIN={0,15}	GPIO where CF1 is connected (default: 5)
HLW8012_CF_PIN={0,15}	GPIO where CF is connected (default: 5)
HLW8012_SEL_CURRENT	SEL pin transition to start measuring. One of: - HIGH (default) - LOW
HLW8012_CURRENT_R=<n>	Current resistor, default: 0.001
HLW8012_VOLTAGE_R_UP	Upstream voltage resistor, default: ( 5 * 470000 )
HLW8012_VOLTAGE_R_DOWN	Downstream voltage resistor, default: ( 1000 )

Notice: some people have reported issues when using HLW8012 with SSL (see #1248).

---

MHZ19 CO2 sensor

Option	Note
MHZ19_RX_PIN	GPIO where RX is connected (default: 13)
MHZ19_TX_PIN	GPIO where TX is connected (default: 15)

---

Particle Monitor based on Plantower PMSX003

Option	Note
PMS_RX_PIN	GPIO where RX is connected (default: 13)
PMS_TX_PIN	GPIO where TX is connected (default: 15)

---

SHT3X environmental sensor

Option	Note
SHT3X_I2C_ADDRESS={0x00-0xFF}	I2C address of SXT3X sensor (default: 0x00 - auto)

Note: This will enable I2C.

---

SI7021 environmental sensor

Option	Note
SI7021_ADDRESS={0x00-0xFF}	I2C address of SI7021 sensor (default: 0x00 - auto)

Note: This will enable I2C.

---

V9261F based power sensor

Option	Note
V9261F_PIN={0,15}	GPIO where V9261 is connected (default: 2)
V9261F_PIN_INVERSE	Is signal inverted? (default: 1 - inverted signal)

---

PZEM004T based power monitor

Option	Note
PZEM004T_RX_PIN	GPIO where RX is connected (default: 13)
PZEM004T_TX_PIN	GPIO where TX is connected (default: 15)
PZEM004T_HW_PORT	Hardware serial port (if PZEM004T_USE_SOFT == 0) (default: Serial1)
PZEM004T_ADDRESSES	Connected devices addresses (default: 192.168.1.1)
PZEM004T_READ_INTERVAL	Read interval between the same device in the bus (default: 1500)
PZEM004T_MAX_DEVICES	Maximum number of devices on the pseudo-bus (default: 3)

See Wiki page for more details: PZEM004t Energy Monitor