IRCC datasheet(61/79 Pages) SMSC

61 / 79 page

Framing Errors

The IrDA FIR pulse and signaling violations listed

in this section are considered framing errors.

When the Frame Error bit in the IrCC Line Status

The IrDA receiver response to framing errors

depends upon when the errors occur. Framing

errors that occur before a valid BOF has been

detected will always set the Frame Error bit but

will not alter the system state in any other way;

i.e., the abort bit is not activated.

If framing

errors occur following a valid BOF, i.e. while

nActive Frame is zero, the message is aborted.

For both the HDLC and 4PPM encoding

schemes, messages with data fields larger than

the value contained in the data size register

violate IrDA framing rules but are not aborted.

NOTE: the Size Error and the Frame Error bits

are set. Pulses less than 60ns should be ignored,

in all modes. The events listed in the following

two sections are framing errors.

1.152Mbps

Pulse Widths greater than one bit-cell. Invalid

BOF: includes data fields before BOF, pulse-

width violations during BOF, and subsequent

invalid BOFs (including Aborts) following a valid

BOF before the Address field. Invalid data fields:

includes frames with invalid data field characters

(including aborts), and pulse-width violations

during a data field (including during CRC).

Invalid EOF fields: includes invalid EOF flags

(including Aborts), pulse-width violations, and

subsequent invalid EOFs following a valid EOF.

4Mbps

Pulse Widths greater than two chip times. Invalid

PA field: includes invalid PA symbols, pulse-

width violations, and subsequent invalid PA

symbols following at least one valid PA symbol

(including Aborts) before the STA field. Invalid

STA field: includes invalid STA symbols, pulse-

width violations, and subsequent invalid STA

symbols following at least one valid symbol

(including Aborts) before the payload data.

Invalid Data field: includes frames with invalid

data symbols (including Aborts), and pulse-width

violations during a data field (including during

CRC). Invalid EOF field: includes invalid EOF

flag (including Aborts), pulse-width violations,

and subsequent invalid EOFs following a valid

EOF.

CONSUMER IR ENCODER TIMING

The Consumer IR-mode SCE does not require

the framing signals that are specified in the IrDA-

mode timing, although both modes utilize the

nActive Frame and EOM Interrupt. There is also

no need to differentiate the IrDA-mode EOM

signal from an inactive nActive Frame.

The

Consumer IR-mode SCE operates at the bit

rates set in the Consumer IR Bit Rate Register.

The Consumer IR-mode SCE can operate in

Programmed I/O or DMA mode.

The CRC

Generator is not used.

Transmit Timing

The SCE TV Remote transmitter uses the same

enabling

mechanisms

the

IrDA-mode

transmitter (see page 57). Note: the IrDA-mode

Active SIP Pulse Tx Enable timing restriction

does not apply. Once enabled, the TV Remote

transmitter operates until the FIFO underruns

(Figure 30).

The nActive Frame and EOM

Interrupt signals behave as shown. The SCE

Modes bits are reset to zero, disabling the

transmitter, following nActive Frame.

IRCC Datasheet(PDF) 61 Page - SMSC Corporation

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