MPL115A1 查看數據表（PDF） - Freescale Semiconductor

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MPL115A1

Miniature SPI Digital Barometer

Freescale Semiconductor 

3.6 Example of SPI Reading of Coefficients

These are MPL115A1 SPI commands to read coefficients, execute Pressure and Temperature conversions, and to read Pressure

and Temperature data. The sequence of the commands for the interaction is given as an example to operate the MPL115A1.

Utilizing this gathered data, an example of the calculating the Compensated Pressure reading is given in floating point notation.

SPI Commands (simplified for communication)

Command to Write “Convert Pressure and Temperature” = 0x24

Command to Read “Pressure ADC High byte” = 0x80

Command to Read “Pressure ADC Low byte” = 0x82

Command to Read “Temperature ADC High byte” = 0x84

Command to Read “Temperature ADC Low byte” = 0x86

Command to Read “Coefficient data byte 1 High byte” = 0x88

Read Coefficients:

[CS=0], [0x88], [0x00], [0x8A], [0x00], [0x8C], [0x00], [0x8E], [0x00], [0x90], [0x00], [0x92], [0x00], [0x94], [0x00], [0x96], [0x00],

[0x00], [CS=1]

Start Pressure and Temperature Conversion, Read raw Pressure:

[CS=0], [0x24], [0x00], [CS=1], [3 ms Delay]

[CS=0], [0x80], [0x00], [0x82], [0x00], [0x84], [0x00,] [0x86], [0x00], [0x00], [CS=1]

NOTE: Extra [0x00] at the end of each sequence to output the last data byte on the slave side of the SPI.

Figure 4. SPI Read Coefficient Datagram

a0 coefficient MSB = 0x41

a0 coefficient LSB = 0xDF a0 coefficient = 0x41DF = 2107.875

b1 coefficient MSB = 0xB0

b1 coefficient LSB = 0x28 b1 coefficient = 0xB028 = -2.49512

b2 coefficient MSB = 0xBE

b2 coefficient LSB = 0xAD b2 coefficient = 0xBEAD = -1.02069

c12 coefficient MSB = 0x38

c12 coefficient LSB = 0xCC c12 coefficient = 0x38CC = 0.00086665

Sensors

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MPL115A1

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