MLX90132 Datasheet, PDF (18/44 Pages) Melexis Microelectronic Systems – 13.56MHz RFID / NFC Transceiver

MLX90132
13.56MHz RFID / NFC Transceiver
6.5 PollField command (0x03)
The “PollField” command is used to detect the presence of an HF field by monitoring the flag “FieldDet”. This
command returns the current value of the flag “FieldDet”. The parameters <Presc> and <Timer> can also be
used to define a time during which the MLX90132 continuously scans for the presence of HFfield. The
answer to the “PollField” command is available with the flag <FieldDet> updated accordingly, after the
scanning period is terminated.
PollField0x03
Direction
Data
03
<Len>
<Flags>
<Presc>
MCU – device
<Timer>
Device - MCU
00
01
<FieldDet>
Comment
Command code
Length of data
Timer flag (Optional)
01 – Wait for field appearance
00 – Wait for field disappearance
Timer prescaler (Optional)
Timer time-out (Optional)
Example
0300 – Check if Field is ON or OFF
0303010FFF– Wait for field appearance
during(16*256)/13.56=302µs
Parameters Flags, Presc and Timer are optional.
They must be specified if application has to wait
for field appearance or disappearance.
The time to wait is:
Result code
Length of data
[7:1] – RFU
[0] – 0 : No HF field detected
1 : HF field detected
Time  ^{(Presc 1)  (Timer 1)} [s]
13.56
000101 – HF field is detected
Table 12: “PollField” command
Note: When the MLX90132 is selected in reader mode (protocol select command), the HF field will be automatically
turned ON and the flag “FieldDet” will be set to ‘1’ (the MLX90132 detects its own field). Consequently, the PollField
command should be used in Tag/Card Emulation state or in Reader state with the HF field set OFF.
3901090132
Rev. 009
Page 18 of 44
Jan-2014