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SA-1110 Developer’s Manual 359
Peripheral Control Module
A register read is performed by writing the address of the register to read while clearing the
read/write bit to zero within MCDR2. Again, the data is transferred to the serial shifter on the next
rising edge of the SFRM signal and is transmitted to the UCB1x00 during subframe 0. Because the
address and read/write control bit fields are placed near the beginning of the serial stream output,
the codec performs the read immediately after the read/write bit is received (during the 41st bit of
the frame), and the value contained within the addressed register is sent back to the MCP in the
same data frame, and is placed within MCDR2.
Once MCDR2 is written with a value to execute a read or write, the operation is performed every
MCP data frame until a new value is written to the register. Thus continual reads or writes are made
to the addressed codec register until a new read or write operation is configured.
The following table shows the location of MCP data register 2. Note that the reset state of all
MCDR2 bits is unknown (indicated by question marks), writes to reserved bits are ignored, and
reads return zeros.
0h 8006 0010 MCP Data Register 2: MCDR2 Read/Write
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved
Register
Address
R/W
0
Data Value Returned by a Codec Register Read or Write
Reset
0 0 0 0 0 0 0 0 0 0 0 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
Read Access
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved
Register
Address
R/W
R/W
Data Value to be Written to the Addressed Codec
Register
Reset
0 0 0 0 0 0 0 0 0 0 0 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
Write Access
(Sheet 1 of 2)
Bits Name Description
15..0
Codec
Register
Read/Write
Data
Codec register read/write data.
Read – If a codec write was last performed, contains data of previous register access; next
frame contains the data that was written. If a codec read was last performed, contains data
from the read register.
Write – Used to specify what data to write to the addressed register, ignored for a codec
register read.
16 R/W
Read/write.
Read – Returns a zero.
Write – Used to control whether the addressed register is read or written (write = 1, read =
0).