MLX90621 datasheet(29/44 Pages) MELEXIS

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MLX90621

16x4 IR array

Datasheet

39001090621

Page 29 of 44

Datasheet IR16x4

Rev 3.0

15 September 2016

Low level communication protocol

9.2.

Start / Stop condition

9.2.1.

Each communication session is initiated by a START condition and ends with a STOP condition. A START condition is

initiated by a HIGH to LOW transition of the SDA while a STOP is generated by a LOW to HIGH transition. Both

changes must be done while the SCL is HIGH (see the figure)

Figure 18: Start / Stop conditions of I

Device addressing

9.2.2.

The master is addressing the slave device by sending a 7-bit slave address after the START condition. The first seven

bits are dedicated for the address and the 8

th is Read/Write (R/W) bit. This bit indicates the direction of the transfer:

•

Read (HIGH) means that the master will read the data from the slave

•

Write (LOW) means that the master will send data to the slave

Mlx90621 is responding to 2 different slave addresses:

for access to internal EEPROM

For access to IR array data

Figure 19: I

2C addresses

Acknowledge

9.2.3.

During the 9

th clock following every byte transfer the transmitter releases the SDA line. The receiver acknowledges

(ACK) receiving the byte by pulling SDA line to low or does not acknowledge (NoACK) by letting the SDA ‘HIGH’.

Low level communication operation

9.2.4.

The low level operation communication is based on 8bits (1byte) transmissions. This includes start/stop event,

acknowledgement and errors detection.

Figure 20: I

2C communication

START

STOP

SCL

SDA

R/W

8 Bits

I2C

transmission

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