wm8903 Wolfson Microelectronics plc, wm8903 Datasheet - Page 101

• Manufacturer Part Number: wm8903
• Description: Ultra Low Power Codec For Portable Audio Applications
• Manufacturer: Wolfson Microelectronics plc

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Table 69 Write Sequencer Control – Initiating a Sequence
PROGRAMMING A SEQUENCE
A sequence consists of write operations to data bits (or groups of bits) within the control registers.
The Register fields associated with programming the Control Write Sequencer are described in Table
70.
For each step of the sequence being programmed, the Sequencer Index must be written to the
WSEQ_WRITE_INDEX field. The values 0 to 31 correspond to all the available RAM addresses
within the Write Sequencer memory. (Note that memory addresses 32 to 48 also exist, but these are
ROM addresses, which are not programmable.)
Having set the Index as described above, Register R109 must be written to (containing the Control
Register Address, the Start Bit Position and the Field Width applicable to this step of the sequence).
Also, Register R110 must be written to (containing the Register Data, the End of Sequence flag and
the Delay time required after this step is executed). After writing to these two registers, the next step
in the sequence may be programmed by updating WSEQ_WRITE_INDEX and repeating the
procedure.
WSEQ_ADDR is an 8-bit field containing the Control Register Address in which the data should be
written.
R108 (6Ch)
Write
Sequencer 0
R111 (6Fh)
Write
Sequencer 3
R112 (70h)
Write
Sequencer 4
REGISTER
ADDRESS
BIT
5:0
9:4
8
9
8
0
WSMD_CLK_E
NA
WSEQ_ABORT
WSEQ_START
WSEQ_START_
INDEX [5:0]
WSEQ_CURRE
NT_INDEX [5:0]
WSEQ_BUSY
LABEL
DEFAULT
00_0000
00_0000
0
0
0
0
Write Sequencer / Mic Detect Clock
Enable.
0 = Disabled
1 = Enabled
Previously called WSEQ_ENA.
Writing a 1 to this bit aborts the
current sequence and returns control
of the device back to the serial
control interface.
Writing a 1 to this bit starts the write
sequencer at the memory location
indicated by the
WSEQ_START_INDEX field. The
sequence continues until it reaches
an “End of sequence” flag. At the
end of the sequence, this bit will be
reset by the Write Sequencer.
Sequence Start Index. This is the
memory location of the first
command in the selected sequence.
0 to 31 = RAM addresses
32 to 48 = ROM addresses
49 to 63 = Reserved
Sequence Current Index. This is the
location of the most recently
accessed command in the write
sequencer memory.
Sequencer Busy flag (Read Only).
0 = Sequencer idle
1 = Sequencer busy
Note: it is not possible to write to
control registers via the control
interface while the Sequencer is
Busy.
PP, Rev 3.1, August 2009
DESCRIPTION
WM8903
101