LPS25HB Datasheet, PDF(20/40 Page) STMicroelectronics – MEMS pressure sensor: 260-1260 hPa absolute digital output barometer

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LPS25HB Datasheet, PDF (20/40 Pages) STMicroelectronics – MEMS pressure sensor: 260-1260 hPa absolute digital output barometer

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Digital interfaces

LPS25HB

Table 13. Transfer when master is writing multiple bytes to slave

Master ST SAD + W

SUB

DATA

Slave

SAK

Table 14. Transfer when master is receiving (reading) one byte of data from slave

Master ST SAD + W

SUB

SR SAD + R

NMAK SP

Slave

SAK

SAK DATA

Table 15. Transfer when master is receiving (reading) multiple bytes of data from slave

Master ST SAD+W

SUB

SR SAD+R

MAK

NMAK SP

Slave

SAK

SAK DATA

DATA

Data are transmitted in byte format (DATA). Each data transfer contains 8 bits. The number

of bytes transferred per transfer is unlimited. Data is transferred with the most significant bit

(MSb) first. If a receiver canât receive another complete byte of data until it has performed

some other functions, it can hold the clock line, SCL LOW to force the transmitter into a wait

state. Data transfer only continues when the receiver is ready for another byte and releases

the data line. If a slave receiver does not acknowledge the slave address (i.e. it is not able to

receive because it is performing some real-time function) the data line must be kept HIGH by

the slave. The master can then abort the transfer. A LOW-to-HIGH transition on the SDA line

while the SCL line is HIGH is defined as a STOP condition. Each data transfer must be

terminated by the generation of a STOP (SP) condition.

In order to read multiple bytes incrementing the register address, it is necessary to assert

the most significant bit of the sub-address field. In other words, SUB(7) must be equal to 1

while SUB(6-0) represents the address of the first register to be read.

In the presented communication format MAK is Master acknowledge and NMAK is no

master acknowledge.

6.3

SPI bus interface

The LPS25HB SPI is a bus slave. The SPI allows writing to and reading from the registers of

the device.

The serial interface interacts with the outside world with 4 wires: CS, SPC, SDI and SDO.

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