BMP390

Overview

• Name: BMP390
• Description:

Arduion library for Bosch BMP390 Digital pressure sensor hardware SPI or I2C.

• Supports sensors features:

1. Read pressure data
2. Read temperature data
3. Tested on SPI interface and I2C interface, Interface is selected by user constructor overload(see examples)
4. Oversampling settings, filter settings and can be set thru API.
5. Normal mode, sleep mode and forced mode supported.
6. Chip ID read: 0x60
7. I2C address is 0x76 or 0x77 depending on SDO pin connection.
8. Supports FIFO and interrupt pin.

• Data sheet

Default settings

These are the default settings for the BMP390 sensor when it is initialized. These settings can be changed using the API functions provided in the library.

BMP390 Setting	Default Enumeration
Power mode	Normal (3)
IIR Filter	filter coefficient (0) bypass-mode
Output data rate (ODR)	ODR_100ODR 100Hz 10ms (2)
Oversampling Temperature	no oversampling (1)
Oversampling Pressure	no oversampling (1)

Examples

File name	Function
SPI_Normal.ino	SPI normal mode
SPI_Forced.ino	SPI forced mode
SPI_Normal_FIFO.ino	SPI normal mode with FIFO buffer & interupt, 3.2 Seconds
I2C_Normal.ino	I2C normal mode
I2C_Forced.ino	I2C forced mode
I2C_Normal_FIFO.ino	I2C normal mode with FIFO buffer & interupt, 9.14 Seconds

Features

Power modes

BMP390 can be operated in three power modes. In sleep mode, no measurements are performed. Normal mode comprises an automated perpetual cycling between an active measurement period and an inactive standby period. In forced mode, a single measurement is performed. When the measurement is finished, the sensor returns to sleep mode.

Filter settings

The environmental pressure is subject to many short-term changes, caused e.g. by slamming of a door or window, or wind blowing into the sensor. To suppress these disturbances in the output data without causing additional interface traffic and processor work load, the BMP390 features an internal IIR filter. The filter coefficient can be set to 0 (bypass mode), 1, 3, 7, 15, 31, 63 or 127. The higher the filter coefficient, the stronger the filtering of the output data. The filter coefficient is set to 0 (bypass mode) by default.

Oversampling settings

Noise depends on the oversampling and filter settings selected. The stated values were determined in a controlled pressure environment and are based on the average standard deviation of 32 consecutive measurement points taken at highest sampling rate. This is required to exclude long term drifts from the noise measurement.

Output data rate (ODR)

The output data rate (ODR) is the rate at which the sensor updates its output data. Control settings for ODR are in odr_sel, data sheet 4.3.20. . The default ODR setting is 50Hz or 20mS. ODR values are in header file under ODR_e enumeration.

Interrupt

The BMP390 has an interrupt pin that can be configured to trigger on various events, such as new data available, FIFO watermark reached, or FIFO full. The interrupt pin can be connected to any GPIO pin and can be used to wake up the MCU from sleep mode or to signal the MCU to read data from the sensor.

FIFO

The BMP390 has a FIFO buffer that can store up to 512 bytes of data. The FIFO can be configured to store pressure and temperature data, and can be set to trigger an interrupt when a certain number of bytes are stored in the FIFO (watermark). This allows for efficient data collection without the need for constant polling of the sensor. See the SPI_Normal_FIFO and I2C_Normal_FIFO examples for how to use the FIFO feature.

The calculation for the interrupt time is:

1. Size of FIFO Buffer = 512 bytes
2. Bytes per frame = 7 bytes
3. Frame-watermark is defined by user in example file
4. ODR period is defined by the ODR set, the available values are in datasheet or ODR-e enum. default 20mS
5. Max frames = Size Of FIFO/bytes per frame
6. Frame watermark/bytes per frame = frames per_read
7. Interrupt time = frames per_read * ODR period.

Example file	ODR period	Frame_watermark	interrupt time
I2C_Normal_FIFO	ODR_3_1_Hz 320 mS	200	9.14 S
SPI_Normal_FIFO	ODR_1_5_Hz 640 mS	35	3.20 S

Connections

The Sensor uses SPI or I2C for communication with the MCU. By default the sensor is 3.3 volts. Some BMP390 breakout modules boards can be powered off 5 Volts. Check your module specifications before connecting to 5V.

SPI Connections

The BMP390 can be connected to the MCU using SPI. The following table shows the pin connections between the BMP390 and the MCU SPI. Example files are setup for ESP32. The BMP390 has a CS pin which can be connected to any GPIO pin on the MCU. Can be set up for any SPI bus speed.

BMP390 Pin	Function	MCU GPIO	Notes
INT	interrupt pin	GPIO 4	Optional, pick any GPIO
CS	Chip Select (CS)	GPIO 15	Active Low pick any GPIO
SDO	MISO (Data Out)	GPIO 19	Master In Slave Out
SDI	MOSI (Data In)	GPIO 23	Master Out Slave In
SCK	SCK (Clock)	GPIO 18	SPI Clock
VCC	Power	VCC	-
GND	Ground	GND	-

I2C Connections

The BMP390 can be connected to the MCU using I2C. The following table shows the pin connections between the BMP390 and the MCU I2C baud rate and port can be adjusted. The BMP390 has a CS pin which can be connected to any GPIO pin on the MCU. The I2C address of the BMP390 is 0x76 or 0x77 depending on the SDO pin connection.

BMP390 Pin	Function	MCU GPIO	Notes
INT	interrupt pin	GPIO 4	Optional, pick any GPIO
CS	Chip Select	n/a	set high
SDO	select I2C address	n/a	high: address=0x77. low: address=0x76
SDI	Data	GPIO 21	I2C Data
SCK	Clock	GPIO 22	I2C Clock
VCC	Power	VCC	-
GND	Ground	GND	-

Debug Mode

Setting BMP390 DEBUG to 1 in the header file will enable verbose debug output during development. This can help with troubleshooting and understanding the sensor's behavior. When BMP390 DEBUG is set to 0, the library will operate in normal mode with less verbose output.

Output

In example files data is outputted to serial monitor, 38400 Uart baud rate connection.