BMP581 datasheet(31/75 Pages) BOSCH

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Bosch Sensortec | BST-BMP581-DS004-11

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Document number: BST-BMP581-DS004-11

as well as in the event of applications for industrial property rights

5 Digital Interface

The device provides one serial interface to the host. It acts as a slave to the host The serial interface is configurable to

the interface protocols SPI, I3C and I2C.

5.1Protocol Selection

The protocol is automatically selected based on the behavior of the signal on the chip select pin CSB after power-up.

After soft reset or power-up, the primary interface of the device is in I²C/I3C mode. If the CSB is connected to VDDIO

during power-up and not changed, the primary interface works in I²C or I3C mode.

For using I²C and I3C, it is recommended to hard-wire the CSB line to VDDIO. Since power-on-reset is only executed

when both VDD and VDDIO are stable, there is no risk of an incorrect protocol detection due to the power-up sequence.

Once the CSB input pin is falling low, the I²C/I3C mode is disabled. The HIF switches over to SPI mode if there are at

least 16 full serial clock (SCK) edges during the CSB low phase, and CSB has risen again. Hence, it is recommended

to perform a single read via SPI of a registers (e.g. to CHIP_ID) before the actual SPI communication with the device.

Note: the content of the retrieved data will be invalid.

The switch from I²C to I3C follows the MIPI I3C specification. Upon power up, the chip stays in I²C mode and once the

dedicated Broadcast I3C Address (7’h7E) is seen on the bus, the chip will disable its I2C feature and the interface stays

in the I3C mode until a soft reset or the next power-up occurs.

The possibles switches among the modes on the digital interface are summarized in Table 15.

Table 16: Possible switches between interface modes

Protocol switch

to I²C

to I3C

to SPI

from I²C

Device ID 7E sent

dummy SPI read

from I3C

power-down or soft-

reset

dummy SPI read

from SPI

power-down or soft-

reset

power-down or soft-

reset

5.2Interface timing

The general interface parameters are given in the table below.

Table 17: General interface parameters

Parameter

Comment

Symbol

Unit

Min

Typ

Max

Input Low Voltage

@VDDIO=1.2V/1.8V/3.3V+/-10%

V_IL

Input High Voltage

@VDDIO=1.2V/1.8V/3.3V+/-10%

V_IH

Input Voltage Hysteresis @VDDIO=1.2V/1.8V/3.3V+/-10%

V_IHYST

Output Low Voltage

@VDDIO=1.2V/1.8V/3.3V+/-10%

V_OL

Output High Voltage

@VDDIO=1.2V/1.8V/3.3V+/-10%

V_OH

Pad Input Leakage

Current (no pull-R)

Input = ‘Low’

I_IL

Pad Input Leakage

Current (no pull-R)

Input = ‘High’

I_IH

Pull-up resistance at

CSB pin

I2C mode, relevant for interface

mode selection

R_PU_CSB kΩ

100

131

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