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MDP200 Datasheet_V1.3

April 2018

7/12

5.5

Trigger measurement operation

MDP200 works in slave mode. The default 7-bit address is 0x31 with a following

bit either write bit(0) or read bit(1).

To trigger a measurement, the master writes a command 0xC1 to slave (sensor),

then wait at least 7ms. The master can read out N bytes data from the register

address 0.

To read differential pressure data, the first byte transmitted must be 0x63 which

indicates that master will read from sensor whose slave address is 0x31.

Immediately with master generating pulses of N bytes, the master can read out

the N bytes data.

For example, the master triggers the measurement first; and then read out the

data in register 0. There are following three steps:

Step 1: Master write into sensor the trigger command 0xC1.

Slave address + write bit

Measurement trigger command

0x62

0xC1

Step 2: Wait at least 7ms.

Step 3: Master reads differential data

Slave address + read bit

N Bytes

0x63

Byte 0 – Byte N-1

Once the slave receives the address and reads bit (0x63) from master, slave

will return N bytes data as shown in the register table in Section 5.4.

With the pulses of N bytes generated by master, slave will return N bytes data.

Note:

1)

Slave returns a high byte first, then the low byte, and at last the CRC code

2)

Trigger measurement command is recommended to be sent after data reading is

completed.

3)

N is number of bytes which master reads from slave, as for how many bytes master read,

it is not constant and is from 1 to 18, if only differential pressure and CRC code are read,

N should be at least 3, if temperature sensor output are read, N should be at least 18.

5.6

Data Format

The output data from slave’s register 0 is 2 bytes signed integer data. If the data

is divided by 50, the result will be the differential pressure which is from -655 to

655 Pa.

The output data from slave’s register 8 is 2 bytes unsigned integer data, it is raw

count output of temperature sensor. It can be converted to the real temperature

(Unit: ℃) using the formula below:

Equation (1)

Tcount = Tcount_Hi × 256 + Tcount_Lo