Sensor libraries¶

SENSOR_BASE · ENV_INCLUDE · QUERY_ · LPP

Seventeen sensor libraries sit in the firmware, and they are all called the same way: an init_ function, a query_ function and a row in one table. What ends up in a build is decided by a series of ENV_INCLUDE_* flags: no flag, no driver. That is exactly the reverse of how RadioLib treats its protocols — see ../library-configuration.md. One sensor driver belongs to the group but appears in no lib_deps line at all.

[!NOTE] Source. This page was verified against the firmware itself: MeshCore v1.16.0, commit 03b6ef4, 28 July 2026 — files platformio.ini r.122-154, src/helpers/sensors/EnvironmentSensorManager.cpp and src/helpers/sensors/RAK12035_SoilMoisture.h.

How MeshCore calls this group¶

All environment sensors sit in one file, EnvironmentSensorManager.cpp, each behind its own #if ENV_INCLUDE_*. Per sensor there are two functions: one to initialise it, one to read it. The latter writes straight into a CayenneLPP buffer:

src/helpers/sensors/EnvironmentSensorManager.cpp r.242-252

#if ENV_INCLUDE_AHTX0
static uint8_t init_ahtx0(TwoWire* wire, uint8_t addr) {
  return AHTX0.begin(wire, 0, addr) ? 1 : 0;
}
static void query_ahtx0(uint8_t ch, uint8_t, CayenneLPP& lpp) {
  sensors_event_t humidity, temp;
  AHTX0.getEvent(&humidity, &temp);
  lpp.addTemperature(ch, temp.temperature);
  lpp.addRelativeHumidity(ch, humidity.relative_humidity);
}
#endif

Those two functions are put in one table together with the I²C address:

src/helpers/sensors/EnvironmentSensorManager.cpp r.547-557

struct SensorDef {
  uint8_t     address;
  const char* name;
  uint8_t   (*init)(TwoWire* wire, uint8_t address);
  void      (*query)(uint8_t channel, uint8_t sub_channel, CayenneLPP& telemetry);
};

static const SensorDef SENSOR_TABLE[] = {
#if ENV_INCLUDE_AHTX0
  { TELEM_AHTX_ADDRESS,    "AHT10/AHT20", init_ahtx0,    query_ahtx0    },
#endif

At start-up MeshCore walks that table, tries each address on the I²C bus and assigns an LPP channel to every sensor found, in table order. Adding a sensor therefore means: declare a library, an ENV_INCLUDE_ flag, two functions and one row in the table.

From build flag to telemetry packet: the ENV_INCLUDE flags decide which
sensor code is compiled in, the sensor table maps each I²C address to an init
and a query function, and those query functions write their values into a
single CayenneLPP buffer that goes out into the mesh as a telemetry
packet

The fifteen from `[sensor_base]`¶

The [sensor_base] section (platformio.ini r.122-154) sets fifteen flags and declares fifteen libraries. Call the section and you get all fifteen.

platformio.ini r.139-144

lib_deps =
  adafruit/Adafruit INA3221 Library @ ^1.0.1
  adafruit/Adafruit INA219 @ ^1.2.3
  robtillaart/INA226 @ ^0.6.4
  adafruit/Adafruit INA260 Library @ ^1.5.3
  adafruit/Adafruit AHTX0 @ ^2.0.5

Adafruit AHTX0 drives the AHT10 and AHT20, cheap temperature and humidity sensors with a fixed I²C address. Supplies temperature and relative humidity.

Adafruit BME280 Library drives the Bosch BME280: temperature, humidity and air pressure in one package. In the repo this is the most common environment sensor outside [sensor_base]; seven variants name a BME280 library.

Adafruit BMP280 Library is the variant without humidity measurement — temperature and pressure.

Adafruit BMP085 Library drives the older BMP085 and BMP180.

Adafruit BME680 Library drives the BME680, which measures a gas resistance alongside temperature, humidity and pressure. Its depends= asks for GFX and SSD1306 for the example sketches.

Adafruit SHTC3 Library drives the Sensirion SHTC3, a compact, low-power temperature and humidity sensor.

Sensirion I2C SHT4x drives the SHT4x range from Sensirion. This is the library that actually drives the SHT4x sensors in the firmware, through SensirionI2cSht4x (EnvironmentSensorManager.cpp r.90-91). It brings in Sensirion Core, which is declared nowhere.

Arduino_LPS22HB drives the ST LPS22HB pressure sensor, as found on the Arduino Nano 33 BLE Sense.

Adafruit MLX90614 Library drives an infrared thermometer that measures the temperature of a surface at a distance, alongside its own ambient temperature. Hence the sub_ch argument in the query_ function: two values from one sensor.

Adafruit_VL53L0X drives a time-of-flight distance sensor, which measures the distance to an object with a laser pulse.

Adafruit INA219, Adafruit INA260 Library, Adafruit INA3221 Library and robtillaart/INA226 measure current and voltage; those four are covered in power.md.

stevemarple/MicroNMEA also belongs to this section but is a GPS library; see gps.md.

finitespace/BME280¶

A second BME280 library, outside [sensor_base], declared in one variant. Unlike the Adafruit version it does not use Adafruit Unified Sensor and supplies its values without that abstraction.

boschsensortec/BSEC Software Library¶

BSEC is Bosch's closed software layer on top of the BME680. Where the ordinary library yields a gas resistance in ohms, BSEC converts that into an air quality index, with a calibration that runs over days. Declared in two variants, lilygo_tbeam_SX1276 and rak4631, behind the ENV_INCLUDE_BME680_BSEC flag with a query_bme680_bsec function of its own.

RAK12035_SoilMoisture — vendored¶

The RAK12035 soil moisture sensor has no lib_deps line. Its driver simply sits in the source, as src/helpers/sensors/RAK12035_SoilMoisture.h and .cpp, and otherwise follows exactly the same pattern as the others: an ENV_INCLUDE_RAK12035 flag, an init_ and a query_rak12035 function and a row in the sensor table. Anyone compiling a sensor list from the platformio.ini files misses this one.

Overview¶

Library	Version	Variants	Flag
`adafruit/Adafruit AHTX0`	`^2.0.5`	3	`ENV_INCLUDE_AHTX0`
`adafruit/Adafruit BME280 Library`	`^2.3.0`	6	`ENV_INCLUDE_BME280`
`adafruit/Adafruit BMP280 Library`	`^2.6.8`	2	`ENV_INCLUDE_BMP280`
`adafruit/Adafruit BMP085 Library`	`^1.2.4`	1	`ENV_INCLUDE_BMP085`
`adafruit/Adafruit BME680 Library`	`^2.0.4`	1	`ENV_INCLUDE_BME680`
`adafruit/Adafruit SHTC3 Library`	`^1.0.1`	1	`ENV_INCLUDE_SHTC3`
`sensirion/Sensirion I2C SHT4x`	`^1.1.2`	1	`ENV_INCLUDE_SHT4X`
`adafruit/Adafruit SHT4x Library`	`^1.0.4`	1	no include found
`arduino-libraries/Arduino_LPS22HB`	`^1.0.2`	1	`ENV_INCLUDE_LPS22HB`
`adafruit/Adafruit MLX90614 Library`	`^2.1.5`	1	`ENV_INCLUDE_MLX90614`
`adafruit/Adafruit_VL53L0X`	`^1.2.4`	1	`ENV_INCLUDE_VL53L0X`
`finitespace/BME280`	`^3.0.0`	1	—
`boschsensortec/BSEC Software Library`	`^1.8.1492`	2	`ENV_INCLUDE_BME680_BSEC`
`RAK12035_SoilMoisture`	vendored	—	`ENV_INCLUDE_RAK12035`

Sources¶

Translated from Dutch by Anthropic Claude