NXP Semiconductors
FXPS7115D4
Digital absolute pressure sensor, 40 kPa to 115 kPa
7.7.9.2 SPI CRC Length and Seed Bits
The SPI_CRC_LEN[1:0] bits select the CRC length for SPI Mode as shown in the table
below. The SPI CRC seed bits contain the seed used for the SPI Mode. The default SPI
CRC is an 8-bit. When the SPI_CRC_LEN[1:0] bits are set to a non-zero value using
a Register Write command, the SPI CRC changes as defined in the table. The new
polynomial value is enabled for both MISO and MOSI on the next SPI Mode command.
The default seed (SPICRCSEED[3:0] = 0h) is FFh for an 8-bit CRC. When the value
is changed to a non-zero value using a Register Write command, the SPI CRC seed
changes to the value programmed as shown in the table. The new seed value is enabled
for both MISO and MOSI on the next SPI Mode command.
Table 57.ꢀSPI CRC Definition
SPI_CRC_LEN[1:0]
SPICRCSEED
CRC Polynomial
x8 + x5 + x3 + x2 + x + 1
x8 + x5 + x3 + x2 + x + 1
x4 + 1
CRC Seed
1111, 1111
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
non-zero
0
0000, SPICRCSEED[3:0]
1010
non-zero
0
x4 + 1
SPICRCSEED[3:0]
111
x3 + x + 1
non-zero
0
x3 + x + 1
SPICRCSEED[2:0]
111
x3 + x + 1
non-zero
x3 + x + 1
SPICRCSEED[2:0]
7.7.10 WHO_AM_I - who am I register (address 3Eh)
The WHO_AM_I register is a user programmed read/write register that contains the
unique product identifier. This register is included in the read/write array error detection.
Table 58.ꢀWHO_AM_I - device identification register (address 3Eh) bit allocation
Bit
7
6
5
4
3
2
1
0
Symbol
WHO_AM_I[7:0]
Factory default (stored value)
Factory default (read value)
Access
0
0
0
1
0
1
0
0
0
0
0
1
0
0
0
0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
The default register value is 00h. If the register value is 00h, a value of C4h is transmitted
in response to a read command. For all other register values, the actual register value is
transmitted in response to a read command.
Table 59.ꢀWHO_AM_I register values
WHO_AM_I register value (hex)
Response to a register read command
00h
C4h
01h to FFh
Actual register value
7.7.11 I2C_ADDRESS - I2C slave address register (address 3Fh)
The I2C slave address register is a user programmed read/write register that contains the
unique I2C slave address. The register is readable in all modes. This register is included
in the read/write array error detection.
FXPS7115D4
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© NXP B.V. 2019. All rights reserved.
Product data sheet
Rev. 3 — 5 December 2019
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