MLX90621 datasheet(10/44 Pages) MELEXIS

10 / 44 page

MLX90621

16x4 IR array

Datasheet

39001090621

Page 10 of 44

Datasheet IR16x4

Rev 3.0

15 September 2016

Initialization

7.1.

After the POR is released the external MCU must execute an initialization procedure.

This procedure must start at least 5ms after POR release.

Read the whole EEPROM (see Figure 4). For maximum speed performance MELEXIS recommends that

the whole calibration data is stored into the client MCU RAM. However it is possible to read the

calibration data from the EEPROM only when needed during calculations. This will result in increased

time for temperature calculation i.e. low refresh rate.

Figure 4 Whole EEPROM dump (SA = 0x50, command = 0x00)

Store the EEPROM content into customer MCU RAM – This step could be omitted resulting in more

data processing time because calibration data needs to be reread for each calculation

Write the oscillator trimming value (extracted from EEPROM content at address 0xF7) into the

corresponding register (0x93).

Figure 5 Write oscillator trimming (SA = 0x60, command = 0x04)

Example: If the value that has to be uploaded is 0x0052 the following sequence must be sent:

Start condition (Falling edge of SDA while SCL is high)

Slave address (SA=0x60) plus write bit = 0xC0

Command = 0x04

LSByte check = LSByte – 0xAA = 0x52 – 0xAA = 0xA8

LSbyte = 0x52

MSByte check = MSByte – 0xAA = 0x00 – 0xAA = 0x56

MSbyte = 0x00

Stop condition (Rising edge of SDA while SCL is high)

Write device configuration value. In EEPROM addresses (0xF5 and 0xF6) MELEXIS provides a typical

value of the configuration register (0x463E). So it is up to the user to copy that value or hardcode a new

value to be loaded into the configuration register. If the EEPROM value is to be used the 16 bits are

combined as follows:

For example: if EEPROM 0xF5 = 0x3E and 0xF6 = 0x46, the Configuration register value is:

0 6:0 5

SCL

SDA

1 0

0 0

0 A

1 0

0 0

DATA(0x00)

Initial address - 0x00

DATA(0x01)

DATA(0xFF)

Slave address

Command

Slave address

SCL

SDA

0 0

1 0

0 A

LSByte check

(LSByte - 0xAA)

LSByte data

MSByte check

(MSByte - 0xAA)

MSByte data

Slave address

Command

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