EVB90620 Datasheet, PDF (10/39 Pages) Melexis Microelectronic Systems – High precision non-contact temperature measurements

MLX90620
16x4 IR array
7.1 Initialization
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. This will result in
increased time for temperature calculation i.e. low refresh rate.
Slave address
Command
Slave address
SDA
Initial address - 0x00
S1 0 1 0 0 0 0 WA 0 0 0 0 0 0 0 0 A S1 0 1 0 0 0 0 R A
DATA(0x00)
A
DATA(0x01)
A
DATA(0xFF)
P
SCL
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).
Slave address
Command
SDA
S1 1 0 0 0 0 0 WA 0 0 0 0 0 1 0 0 A
LSByte check
(LSByte - 0xAA)
A
LSByte data
MSByte check
(MSByte - 0xAA)
A
A
MSByte data
AP
SCL
sent:
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
1. Start condition (Falling edge of SDA while SCL is high)
2. Slave address (SA=0x60) plus write bit = 0xC0
3. Command = 0x04
4. LSByte check = LSByte – 0xAA = 0x52 – 0xAA = 0xA8
5. LSbyte = 0x52
6. MSByte check = MSByte – 0xAA = 0x00 – 0xAA = 0x56
7. MSbyte = 0x00
8. 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 (0x740E). 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 = 0x0E and 0xF6 = 0x74, the Configuration register value is:
Configuration _ register _ value {0xF6 : 0xF5} 0x740E
Slave address
Command
SDA
S1 1 0 0 0 0 0 WA 0 0 0 0 0 0 1 1 A
LSByte check
(LSByte - 0x55)
A
LSByte data
MSByte check
(MSByte - 0x55)
MSByte data
(15:11)
(9:8)
A
A
1
AP
SCL
Figure 6 Write configuration register (SA = 0x60, command = 0x03)
3001090620
Rev 4.0
Page 10 of 40
Datasheet IR16x4
19 September 2012