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Product data sheet
Rev. 3.3 — 3 April 2012
40 of 132
Contactless reader IC
The default coding of a data stream is done by using the Bit-Generator. It is activated
when the value of TxFrameCon.DCodeType is set to 0000 (bin). The Bit-Generator
encodes the data stream byte-wise and can apply the following encoding steps to each
1. Add a start-bit of specified type at beginning of every byte
2. Add a stop-bit and EGT bits of a specified type. The maximum number of EGT bit is 6,
only full bits are supported
3. Add a parity-bit of a specified type
4. TxFirstBits (skips a given number of bits at the beginning of the first byte in a frame)
5. TxLastBits (skips a given number of bits at the end of the last byte in a frame)
6. Encrypt data-bit (MIFARE encryption)
TxFirstBits and TxLastBits can be used at the same time. If only a single data byte is sent,
it must be ensured that the range of TxFirstBits and TxLastBits do not overlap. It is not
possible to skip more than 8 bit of a single byte! ( (8 - TxFirstBits) + (8 - TxLastBits) ) < 8
By default, data bytes are always treated LSB first. To make use of a MSB first coding, the
TxMSBFirst in the register CLCON1 needs to be set.
8.6.3 Receiver circuitry
The CLRC663 features a versatile quadrature receiver architecture with fully differential
signal input at RXP and RXN. It can be configured to achieve optimum performance for
reception of various 13.56 MHz based protocols.
For all processing units various adjustments can be made to obtain optimum
Fig 27. Example 2: overshoot_t1 = 0d; overhoot_t2 = 5d