LPS331AP Datasheet, PDF (13/36 Pages) STMicroelectronics – MEMS pressure sensor: 260-1260 mbar absolute digital output barometer

LPS331AP
Digital interfaces
5.3.1
SDO are respectively the serial port data input and output. Those lines are driven at the
falling edge of SPC and should be captured at the rising edge of SPC.
Both the read register and write register commands are completed in 16 clock pulses or in
multiples of 8 in the case of multiple bytes read/write. Bit duration is the time between two
falling edges of SPC. The first bit (bit 0) starts at the first falling edge of SPC after the falling
edge of CS while the last bit (bit 15, bit 23, ...) starts at the last falling edge of SPC just
before the rising edge of CS.
bit 0: RW bit. When 0, the data DI(7:0) is written into the device. When 1, the data DO(7:0)
from the device is read. In the latter case, the chip will drive SDO at the start of bit 8.
bit 1: MS bit. When 0, the address will remain unchanged in multiple read/write commands.
When 1, the address will be auto incremented in multiple read/write commands.
bit 2-7: address AD(5:0). This is the address field of the indexed register.
bit 8-15: data DI(7:0) (write mode). This is the data that is written into the device (MSb first).
bit 8-15: data DO(7:0) (read mode). This is the data that is read from the device (MSb first).
In multiple read/write commands further blocks of 8 clock periods are added. When the MS
bit is 0 the address used to read/write data remains the same for every block. When MS bit
is 1 the address used to read/write data is increased at every block.
The function and the behavior of SDI and SDO remain unchanged.
SPI read
Figure 5. SPI read protocol
CS
SPC
SDI
SDO
RW
MS AD5 AD4 AD3 AD2 AD1 AD0
DO7 DO6 DO5 DO4 DO3 DO2 DO1 DO0
The SPI Read command is performed with 16 clock pulses. The multiple byte read
command is performed adding blocks of 8 clock pulses at the previous one.
bit 0: READ bit. The value is 1.
bit 1: MS bit. When 0 do not increment address, when 1 increment address in multiple
reading.
bit 2-7: address AD(5:0). This is the address field of the indexed register.
bit 8-15: data DO(7:0) (read mode). This is the data that is read from the device (MSb first).
bit 16-... : data DO(...-8). Further data in multiple byte readings.
Doc ID 022112 Rev 7
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