DS-0355 Datasheet, PDF (6/16 Pages) All Sensors Corporation – DLH Series Low Voltage Digital Pressure Sensors

Digital Interface Data Format
For either type of digital interface, the format of data returned from the sensor is the same. The first byte consists of the
Status Byte followed by a 24-bit unsigned pressure value and a 24-bit unsigned temperature value. Unused bits
beyond the calibrated bit width are undefined, and may have any value. See the Pressure Output Transfer Function
and Temperature Output Transfer Function definitions on page 3 for converting to pressure and temperature.
Refer to Table 2 for the overall data format of the sensor. Table 3 shows the Status Byte definition.
Note that a completed reading without error will return status 0x40.
Table 2 - Output Data Format
S[7:0]
Status
Byte
P[23:16]
Pressure
MSB
P[15:8]
Pressure
Byte 1
P[7:0]
Pressure
LSB
T[23:16]
Temperature
MSB
T[15:8]
Temperature
Byte 1
T[7:0]
Temperature
LSB
Table 3- Status Byte Definition
Bit Description
Bit 7 [MSB] [Always = 0]
6
Power : [1 = Power On]
5
Busy: [ 1 = Processing Command, 0 = Ready]
4:3 Mode: [00 = Normal Operation ]
2
Memory Error [ 1 = EEPROM Checksum Fail]
1
Sensor Configuration [ always = 0]
Bit 0 [LSB] ALU Error [1 = Error]
I2C Interface
I2C Command Sequence
The part enters Idle state after power-up, and waits for a command from the bus master. Any of the five
Measurement commands may be sent, as shown in Table 1. Following receipt of one of these 3-byte commands,
the EOC pin is set to Low level, and the sensor Busy bit is set in the Status Byte. After completion of measurement
and calculation in the Active state, compensated data is written to the output registers, the EOC pin is set high,
and the processing core goes back to Idle state. The host processor can then perform the Data Read operation,
which for I2C is simply a 7-byte Device Read.
If the EOC pin is not monitored, the host can poll the Status Byte by repeating the Status Read command, which
for I2C is a one-byte Device Read. When the Busy bit in the Status byte is zero, this indicate that valid data is
ready, and a full Data Read of all 7 bytes may be performed.
DLH Series Low Voltage Digital Pressure Sensors
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