bmx280thp
—
Driver for Bosch BMP280/BME280 sensor chip via I2C bus
bmx280thp* at iic? addr 0x76
bmx280thp* at iic? addr 0x77
bmx280thp* at spi? slave 0
bmx280thp* at spi? slave 1
The bmx280thp
driver provides measurements from the
BMP280 and BME280 temperature, humidity and barometric pressure sensors via
the envsys(4) framework. The
bmx280thp
addr argument selects
the address at the iic(4) bus and
the bmx280thp
slave argument
selects which chip select will be used on the
spi(4) bus. The precision of the
measurement which is related to the over sampling performed on the measurement
can be changed through sysctl(8)
nodes.
The following sysctl(3) variables
are provided:
hw.bmx280thp0.osrs_t
-
hw.bmx280thp0.osrs_p
-
hw.bmx280thp0.osrs_h
- These control oversampling of temperature, pressure and humidity. The
valid values are 1, 2, 4, 8, and 16 times oversample. Humidity is only
available if the chip is a BME280.
hw.bmx280thp0.irr_samples
- IRR is a filter that can be used to reduce the noise in the measurement.
The value values are 1 (or off), 2, 5, 11 and 22 samples to reach >=
75% of the step response.
hw.bmx280thp0.waitfactor.t
-
hw.bmx280thp0.waitfactor.p
-
hw.bmx280thp0.waitfactor.h
- These control the wait multiplication factor for a measurement cycle. This
factor is different for temperature, pressure and humidity and is based
upon the values of osrs_t, osrs_p and osrs_h. If the chip does not return
the correct measurements for a given over sampling then the wait factors
can be adjusted to allow more time for the measurement to complete
successfully.
hw.bmx280thp0.debug
-
hw.bmx280thp0.dump_calibration
- If the driver is compiled with
BMX280_DEBUG
, these
nodes will appear and can be used to set the debugging level and provide
the calibration constants, upon refresh, that are stored in the chip.
Since the constants are fixed, this is a boolean node and will reset back
to false once one dump has been performed.
hw.bmx280thp0.readattempts
- A status register tells the driver if the chip is busy with a measurement.
This status register must be polled and readattempts is the number of
times that this poll will be performed. The default is 25 which should be
more than enough for most purposes.
The bmx280thp
driver first appeared in
NetBSD 10.0.
The driver does not support the continuous read mode that the BMP280 and BME280
has.