mfrc531 NXP Semiconductors, mfrc531 Datasheet - Page 77

• Manufacturer Part Number: mfrc531
• Description: Iso/iec 14443 Reader Ic
• Manufacturer: NXP Semiconductors

NXP Semiconductors
MFRC531_34
Product data sheet
PUBLIC
11.2.1.2 RF channel redundancy and framing
11.2.1.3 Transmission of bit oriented frames
11.2.1.4 Transmission of frames with more than 64 bytes
Each ISO/IEC 14443 A transmitted frame consists of a Start Of Frame (SOF) pattern,
followed by the data stream and is closed by an End Of Frame (EOF) pattern. These
different phases of the transmission sequence can be monitored using the PrimaryStatus
register ModemState[2:0] bit; see
Depending on the setting of the ChannelRedundancy register bit TxCRCEn, the CRC is
calculated and appended to the data stream. The CRC is calculated according to the
settings in the ChannelRedundancy register. Parity generation is handled according to the
ChannelRedundancy register ParityEn and ParityOdd bits settings.
The transmitter can be configured to send an incomplete last byte. To achieve this the
BitFraming register’s TxLastBits[2:0] bits must be set at above zero (for example, 1). This
is shown in
Figure 15
All fully transmitted bytes are followed by a parity check bit but the incomplete byte is not
followed by a parity check bit. After transmission, the TxLastBits[2:0] bits are automatically
cleared.
Remark: If the TxLastBits[2:0] bits are not equal to zero, CRC generation must be
disabled. This is done by clearing the ChannelRedundancy register TxCRCEn bit.
To generate frames of more than 64 bytes, the microprocessor must write data to the
FIFO buffer while the Transmit command is active. The state machine checks the FIFO
buffer status when it starts transmitting the last bit of the data stream; the check time is
marked in
Fig 15. Transmitting bit oriented frames
TxLastBits = 0
TxLastBits = 7
TxLastBits = 1
shows the data stream if bit ParityEn is set in the ChannelRedundancy register.
Figure 16
Figure
15.
SOF
SOF
SOF
with arrows.
Rev. 3.4 — 26 January 2010
0
0
0
056634
Section 11.2.4 on page
7
7
7
P
P
P
0
0
0
EOF
82.
ISO/IEC 14443 reader IC
6
MFRC531
© NXP B.V. 2010. All rights reserved.
7
EOF
P
EOF
001aak618
77 of 116