MLX90609

Angular Rate Sensor (Standard version)

390109060901

Page 9 of 22

Data Sheet

Rev 008

February/08

5.2 Communication with the MLX90609 through the SPI

The MLX90609 has a serial communication interface compatible with Serial Peripheral Interface

(SPI). Likewise SPI the Serial Interface of the MLX90609 specifies four signals:

serial clock (SCLK);

master data output, slave data input (MOSI);

master data input, slave data output (MISO); and

slave select (SS ).

The MLX90609 always operates as a slave. Therefore only MISO pin is an output.

data will not be accepted via the MOSI pin. The serial output pin (MISO) will remain in a high

impedance state. High level of SS forces the serial interface into the start state of data exchange.

Data is serially transmitted to the MLX90609 in 8 bit words (an instruction byte) and in 16 bit data

words. Data is serially received from the MLX90609 in 16 bit words (an answer word). Most

Significant Bit (MSB) is the first bit transmitted and received.

Transmission:

After the device is selected with SS going low, the instruction byte will be received by the

MLX90609. On each rising edge of SCLK data from MOSI enter into an internal 8-bit shift register.

The accepted instruction byte contains the op-code that defines the operations to be performed.

Along with op-code this byte can also contain information such as EEPROM address or ADC mode

(to be setup).

Reception:

After the 8th bit is received to the shift register, the command will be executed by the MLX90609.

The format of the outgoing data is defined by the received instruction. All instructions evoke an

answer. A full communication cycle (transmitting an instruction and receiving the full answer) is

finished after 24th clock of the SCLK. Communication can be terminated by putting SS high.

Some remarks:

If an invalid op-code is received, it is rejected and the corresponding data is ignored. In this

case a special

It's recommended to use synchronization by SS after every data exchange to prevent a data

distortion.

If high level is applied to SS during an instruction byte transmission, the command will be

ignored.

If high level is applied to SS during the answer reception, the answer will be truncated. This

can be used to limit the reading of the answer to e.g. one byte only (see Figure 5-3).