MLX90132 Datasheet, PDF (10/44 Pages) Melexis Microelectronic Systems – 13.56MHz RFID / NFC Transceiver

MLX90132
13.56MHz RFID / NFC Transceiver
5.2 SPI
5.2.1 Polling mode
In order to send commands and receive answers, the application software has to pass 3 stages:
1. Send the command to the MLX90132
2. Poll the MLX90132 until it is ready to transmit the response.
3. Read the response.
The application software should never read the MLX90132 without being sure that the MLX90132 is ready to
send its response.
The maximum allowed communication speed is 2Mbps. Please note that the communication speed is limited
to 1.5Mbps in case of TAG emulation mode with “clock recovery” option selected (“ClkRec” in Table 11,
TAG/Card emulation mode).
A Control byte is used to specify the communication type and direction (see pictures below):
– 00: Send command to the MLX90132
– 11: Poll the MLX90132
– 10: Read data from the MLX90132
– 01: Reset the MLX90132
The SPI_NSS line is used to select a device on the common SPI bus; the SPI_NSS active level is LOW.
When the SPI_NSS line is inactive, all data sent by the application will be ignored and the SPI_MISO line will
be set in high impedance state.
Sending command to the MLX90132
MOSI
Control byte
MISO
Several data bytes
Polling the MLX90132 until it is ready
MOSI
Control byte
MISO
Polling Flags until ready
Figure 7: SPI communication, sending command & polling method
The following table shows the meaning of the flags returned by the MLX90132 device.
Bit
Description
[4:7]
RFU, will be set to “0000”
3
Data can be read from MLX90132 when set
2
Data can be sent to MLX90132 when set
[1:0]
MLX Reserved
Table 4: Interpretation of SPI flags
3901090132
Rev. 009
Page 10 of 44
Jan-2014