FS1015 Datasheet

R36DS0008EU0100 Rev.1.00

Jun 2, 2022

Page 8

4.3

Digital Output Measurements

The FS1015 continuously measures during operation. The data is sent in byte packages. Each byte is followed

by an ACK from the slave. The most significant bit (MSB) is transmitted first.

To read the data, the following command is sent to the FS1015.

After the START bit, the master device sends the 7-bit slave address followed by an eighth bit = 1 (READ). The

READ bit indicates a transmission from the FS1015 (slave) to master (see Figure 7).

The checksum used for data integrity is returned from the FS1015 followed by the two bytes of flow data.

The flow data is a 12-bit integer. Only the least significant four bits in the high byte are valid (see Figure 8).

Figure 7. Flow Data Read Command

Figure 8. Flow Data from FS1015

4.4

Calculating Checksum

The checksum used for data integrity is the 2’s complement (negative) of the 256-modulo (8-bit) sum of the data

bytes (does not include I2C address).

Figure 8 shows the 5 bytes read:

Example:

Byte 1, 0xCC (Checksum)

Byte 2, 0x01

Byte 3, 0x99

Byte 4, 0x01 or 0x00

Byte 5, 0x99 or 0x00

6

5

4

3

2

1

0

S

1

0

1

0

0

0

Device Slave Address (0x50), [6:0]

Byte

7

6

5

4

3

2

1

0

A

7

6

5

4

3

2

1

0

A

7

6

5

4

3

2

1

0

A

Byte 3

Sensor Flow Data, Low Byte [7:0]

Checksum [7:0]

Byte 1

Byte 2

Sensor Flow Data, High Byte [3:0]

7

6

5

4

3

2

1

0

A

7

6

5

4

3

2

1

0

A

P

Byte 4

Byte 5

Generic Checksum Data [7:0]

Generic Checksum Data [7:0]

S START Condition

R READ Mode

P STOP Condition