
17-16
MCF5249UM
MOTOROLA
Digital Audio Interface (EBU)
17.3.1.8
U and Q Receive Register Interrupts
UChannelRcvFull — Receive register full
UChannelRcvOverrun — Overrun error
QChannelRcvFull — Receive register full
QChannelOverrun — Overrun error on Q channel
ChannelSyncFound — Received sync on U/Q channel.
ChannelLengthError — Set when ChannelSyncFound occurs when there are less than 32 bits
waiting in QchannelReceive register, or less than 4 bytes in UChannelReceive, or when a syncing
error is found. To regain correct syncing, U channel receive register and Q channel receive register
must be read to establish correct synchronization.
On the input interface, 2 data receive registers are defined:
1. UChannelReceive — 32-bit register to receive incoming subcode.
2. QChannelReceive — 32-bit register to receive Q channel of incoming subcode.
The hardware associated with IEC958 receiver U-channel reception is intended for reception of the
following kind of data:
CD or CD-compatible User channel subcode (P,Q and R-W, or Q and R-W). See the CD Red Book
specification for a detailed description.
Other types of subcode.
17.3.1.9
Behavior of User Channel Receive Interface (CD Data)
This section details the behavior of the user channel receive interface on incoming CD user channel
subcode in the IEC958 receiver. This mode is selected if UsyncMode (bit 1) in register CD-Subcode
control, is set.
The CD subcode stream embedded into the IEC958 User channel consists of a sequence of packets.
Every packet contains 98 symbols. The first two symbols of every packet are sync symbols and the other
96 symbols are data symbols.
Any sequence found in the IEC958 U-channel stream starting with a leading one, followed by 7 information
bits, is recognized as a data symbol. Subsequent data symbols are separated by pauses. During the
pause, zero bits are seen on the IEC958 U-channel.
Data symbols come in MSB first. The MSB is the leading one and is always received as bit 7.
1
USYNCMODE
EBU1
1: CD user channel reception
0: Other data.
0
UCHANTXTIM
0: Timing to reg. UChannelTx from
cd-text output interface
1: Timing to reg. UChannelTx from
EBU1 output interface
1. On read back, last written value is returned
2. On read back, zero is returned
3. PRESETCOUNT(6:0) will only affect the free running counter when the register is written with
PRESETEN = ‘1’. Writing with PRESETEN = ‘0’ does not affect the counter.
Table 17-16 CD-Subcode Register Bit Descriptions (Continued)
FIELD
BITS
MODE
DESCRIPTION
NOTES
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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