MLX90640 Datasheet, PDF (7/12 Pages) Melexis Microelectronic Systems – MLX90640 32x24 IR array

MLX90640 32x24 IR array
Short form Datasheet
7.2. Communication protocol
Low level
Start / Stop conditions
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.
Device addressing
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
Acknowledge
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’.
I²C command format
SDA
I²C write
SCL
Slave address
MSByte address
LSByte address
MSByte data
S 0 1 1 0 0 1 1 WA
A
A
A
LSByte data
AP
Figure 2 I²C write command format (default SA=0x33 is used)
Slave address
Slave address
MSByte address
LSByte address
MSByte data
LSByte data
I²C read ^SDA
S 0 1 1 0 0 1 1 WA
A
A S 0 1 1 0 0 1 1 WA
A
NAK P
SCL
Figure 3 I²C read command format (default SA=0x33 is used)
7.3. Device modes
The device can operate in following modes:
• Normal mode
• Step mode
Normal mode
In this mode the measurements are constantly running. Depending on the selected frame rate Fps in the control
register, the data for IR pixels and Ta will be updated in the RAM each 1/Fps seconds. In this mode the external
microcontroller has full access to the internal registers and memories of the device.
REVISION 3 – NOVEMBER 4, 2016
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