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Bosch Sensortec | BMP388 Datasheet

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Modifications reserved |Data subject not change without notice | Printed in Germany

Document number: BST-BMEP388-DS001-01 Revision_1.1_032018

5. Digital interfaces

The BMP388 supports the I²C and SPI digital interfaces; it acts as a slave for both protocols. The I²C interface supports the

standard, fast and high speed modes. The SPI interface supports both SPI mode ‘00’ (CPOL = CPHA = ‘0’) and mode ‘11’

(CPOL = CPHA = ‘1’) in 4-wire and 3-wire configuration.

The following transactions are supported:



Single byte write



Multiple byte write (using pairs of register addresses and register data)



Single byte read



Multiple byte read (using a single register address which is auto-incremented)

5.1.

Interface selection

Interface selection is done automatically based on CSB (chip select) status. If CSB is connected to VDDIO, the I²C interface is

active. If CSB is pulled down, the SPI interface is activated. After CSB has been pulled down once (regardless of whether

any clock cycle occurred), the I²C interface is disabled until the next power-on-reset. This is done in order to avoid

inadvertently decoding SPI traffic to another slave as I²C data. Since power-on-reset is only executed when both VDD and

VDDIO are established, there is no risk of incorrect protocol detection due to power-up sequence used. However, if I²C is to

be used and CSB is not directly connected to VDDIO but rather through a programmable pin, it must be ensured that this pin

already outputs the VDDIO level during power-on-reset of the device. If this is not the case, the device will be locked in SPI

mode and not respond to I²C commands.

5.2.

I²C Interface

The I²C slave interface is compatible with Philips I²C Specification Revision 6 (April 2014). For detailed timings refer to Table

47. All modes (standard, fast, high speed) are supported. SDA and SCL are not pure open-drain. Both pads contain ESD

protection diodes to VDDIO and GND.

Figure 14: SDI/SCK ESD drawing

The 7-bit device address is 111011x. The 6 MSB bits are fixed. The last bit is changeable by SDO value and can be changed

during operation. Connecting SDO to GND results in slave address 1110110 (0x76); connection it to VDDIO results in slave

address 1110111 (0x77), which is the same as BMP180’s I²C address. The SDO pin cannot be left floating; if left floating, the

I²C address will be undefined.

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