DS-0355 Datasheet, PDF (8/16 Pages) All Sensors Corporation – DLH Series Low Voltage Digital Pressure Sensors

SPI Interface
SPI Command Sequence
As with the I2C interface configuration, the part enters Idle state after power-up, and waits for a command from the SPI master.
To start a measurement cycle, one of the 3- byte Measurement Commands (see Table 1) must be issued by the master.
The data returned by the sensor during this command request consists of the Status Byte followed by two undefined data bytes.
On successful decode of the command, the EOC pin is set Low as the core goes into Active state for measurement and calcula-
tion. When complete, updated sensor data is written to the output registers, and the core goes back to the Idle state. The EOC
pin is set to a High level at this point, and the Busy status bit is set to 0. At any point during the Active or Idle periods, the SPI
master can request the Status Byte by sending a Status Read command (a single byte with value 0xF0).
As with the I2C configuration, a Busy bit of value 0 in the Status Byte or a high level on the EOC pin indicates that a valid data
set may be read from the sensor. The Data Read command must be sent from the SPI master (The first byte of value 0xF0 fol-
lowed by 6 bytes of 0x00).
NOTE: Sending command data that is not defined in this document may cause unexpected device behavior.
SPI Bus Communications Overview
The sequence of bits and bus signals are shown in the following illustration (Figure 4). Refer to Figure 5 in the Interface
Timing Diagram section for detailed timing data.
Figure 4 - SPI Communications Diagram
Measurement Command
SCLK
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MOSI XXXX
First Command Byte (0xAA / 0xAC / 0xAD / 0xAE / 0xAF)
C₂₃
C₂₂
C₂₁
C₂₀
C₁₉
C₁₈
C₁₇
C₁₆
Lower Command Bytes (0x00 0x00)
C ₁₅
---
C₁
C₀
XXXX
MISO HI-Z
S₇
S₆
S₅
S₄
S₃
S₂
S₁
S₀
XX
---
XX
XX HI-Z
S₇ … S₀ (Status)
(Undefined Data)
SS
---
Read Status Command
SCLK
Command (0xF0)
MOSI Don't Care 1
1
1
1
0
0
0
0 Don't care
MISO Hi-Z
SS
S₇
S₆
S₅
S₄
S₃
S₂
S₁
S₀
S₇ … S₀ (Status)
Hi-Z
Data Read Command
SCLK
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MOSI
Command (0xF0 then 6 bytes of 0x00)
Don't Care 1 1 1 1 0 0 0 0 0 0 - - - 0 0 0 0 - - - 0 0 Don't Care
MISO
SS
Hi-Z
S₇ S₆ S₅ S₄ S₃ S₂ S₁ S₀ P₂₃ P₂₂ - - - P₁ P₀ T₂₃ T₂₂ - - - T₁ T₀
S₇ … S₀ (Status)
P₂₃…P₀ (Pressure)
T₂₃…T₀ (Temperature)
Hi-Z
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DLH Series Low Voltage Digital Pressure Sensors
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