CLRC63201TSLASH0FE datasheet(121/163 Pages) PHILIPS

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Philips Semiconductors

Product Specification Rev. 3.0; May 2003

Multiple Protocol Contactless Reader IC

CL RC632

121

Confidential

18.4.2.4 Receiving Bit Oriented Frames

The receiver can handle byte streams with incomplete bytes, resulting in bit oriented frames. To support this,

the following values may be used:

•

RxAlign selects a bit offset for the first incoming byte, e.g. if RxAlign is set to 3, the first 5 bits received

are forwarded to the FIFO buffer. Further bits are packed into bytes and forwarded. After reception,

RxAlign is cleared automatically.

If RxAlign is set to zero, all incoming bits are packed into one byte.

•

RxLastBits returns the number of bits valid in the last received byte, e.g. if RxLastBits evaluates to 5 at

the end of the receiving command, the 5 least significant bits are valid.

RxlastBits evaluates to zero if the last byte is complete.

RxLastBits is valid only, if no frame error is indicated by the flag FrameErr. If RxAlign is set to a value other

than zero and also ParityEn is active, the first parity bit is not checked but ignored.

18.4.2.5 Communication Errors

The following table shows which event causes the setting of error flags:

Cause

Bit, that is set

Received data did not start with a SOF pattern.

FramingErr

The CRC block is not equal the expected value.

CRCErr

The received data is shorter than the CRC block.

CRCErr

The parity bit is not equal the expected value (e. g. a bit collision occurs when a parity is expected)

ParErr

A collision is detected.

CollErr

Table 18-3: Communication Error Table

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