Module bmp280 

Bosch BMP280 digital pressure sensor.

The BMP280 is the BME280’s sibling without the humidity element: a barometric pressure and temperature sensor that ships 20-bit raw ADC codes plus a block of per-chip trimming coefficients, and leaves the compensation to the host. The integer arithmetic here is a line for line port of the bmp280_compensate_T_int32 and bmp280_compensate_P_int64 reference code in section 3.11.3 of the data sheet (BST-BMP280-DS001), and the tests cross-check it against the data sheet’s floating-point form in appendix 8.1.

A caller reads the 24 calibration bytes once with Calibration::parse, then burst-reads the six data registers each cycle into a Measurement and calls Calibration::compensate for a Reading. CtrlMeas and Config build and decode the two control registers, and every decode has a matching builder so a node can be exercised with nothing wired. The measurement-time functions are here too, and the Bmp280 driver (the embedded-hal feature) runs the whole sequence, reset to reading, over an I2C or SPI bus.

Modules

register

The BMP280 register addresses.

sim

A BMP280 that is not there.

Structs

Bmp280

A BMP280 on an I2C or SPI bus, measuring on demand in forced mode.

Calibration

The per-chip trimming coefficients read from 0x88..=0x9F.

Config

The configuration register (0xF5, config).

CtrlMeas

The measurement control register (0xF4, ctrl_meas).

Measurement

The raw, uncompensated 20-bit codes from the BMP280 data registers.

Reading

A compensated BMP280 reading.

Enums

Mode

The power mode selected by the mode[1:0] field.

Oversampling

An oversampling setting for the pressure or temperature measurement.

Standby

The inactive period between measurements in normal mode, the t_sb[2:0] field.

Constants

CALIBRATION_LEN

The number of calibration bytes at register::CALIBRATION.

CHIP_ID

The value the chip-id register (0xD0) returns for a BMP280.

DATA_LEN

The number of data bytes at register::DATA.

I2C_ADDRESS_PRIMARY

The I2C address with the SDO pin tied to ground.

I2C_ADDRESS_SECONDARY

The I2C address with the SDO pin tied to VDDIO.

RESET_WORD

The word written to the reset register (0xE0) to run a full power-on reset.

SKIPPED_OUTPUT

The raw code a data register holds when its measurement is skipped.

STARTUP_MICROS

The start-up time from power-on or reset until the part accepts a transfer, in microseconds: Table 2’s t_startup, 2 ms at most, which the soft reset of section 4.3.2 incurs again since it runs the complete power-on-reset procedure.

STATUS_POLLS

How many times the status register is polled, 1 ms apart, before a conversion or a reset is called overdue.

Functions

image_updating

Returns whether the status register reports the NVM image being copied.

max_measurement_micros

The longest one measurement cycle can take, in microseconds.

measuring

Returns whether the status register reports a conversion in progress.

typical_measurement_micros

The typical time one measurement cycle takes, in microseconds.