MLX90132 Datasheet, PDF (11/44 Pages) Melexis Microelectronic Systems – 13.56MHz RFID / NFC Transceiver

MLX90132
13.56MHz RFID / NFC Transceiver
Reading data from the MLX90132
MOSI
Control byte
MISO
Several data bytes
Figure 8: SPI communication, reading data from the MLX90132
Data must be sampled by the rising edge of the SPI_SCK signal.
‘Sending’, ‘Polling’ and ‘Reading’ commands must be separated by a high level of the SPI_NSS line.
For example, when the application needs to wait for data from the MLX90132, it sets to low the pin SPI_NSS
and issues a ‘Polling’ command. By keeping the SPI_NSS “low”, the application can continuously read the
Flags waiting for the bit indicating that the MLX90132 is ready (the flags will be automatically updated, no
need to send several polling commands).Then, the application has to set high the pin SPI_NSS to finish the
polling sequence. The application puts low again the pin SPI_NSS to issue a ‘Reading’ command to read
data. When all data is read, the application sets high the pin SPI_NSS to terminate the communication.
The MLX90132 can issue as many 'Polling' commands as necessary.
For example, the application sets low the pin SPI_NSS to issue a 'Polling' commands. If the MLX90132 is not
ready, the application can put high the pin SPI_NSS and continue its operations. Then, as soon as the
application is ready again, it sets low the pin SPI_NSS to issue a 'Polling' commands, to see if the MLX90132
is ready. These operations are not time critical which makes it easy to insert in the application flow.
Reset MLX90132
MOSI
Control byte
MISO
Figure 9: SPI communication reset the MLX90132
Control byte 0x01 resets the MLX90132 and places the device in Power-up state. A wake-up sequence is
then necessary to start again the communication with the MLX90132.
Warning: The SPI communication is most significant bit (MSB) first.
5.2.2 IRQ mode
When the MLX90132 is configured to use the SPI serial interface, the pin IRQ_OUT is used to give additional
information to the application. When the MLX90132 is ready to send back a reply it sends an Interrupt
request by setting a low level on pin IRQ_OUT, which remains low until the application reads the data. The
application can use the IRQ mode to skip the polling stage.
3901090132
Rev. 009
Page 11 of 44
Jan-2014