WM8904ECSSLASHR datasheet(126/188 Pages) WOLFSON

126 / 188 page

WM8904

Pre-Production

PP, Rev 3.3, September 2012

126

The Write Sequencer can be interrupted by writing a logic 1 to the WSEQ_ABORT bit.

The current status of the Write Sequencer can be read using two further register fields - when the

WSEQ_BUSY bit is asserted, this indicates that the Write Sequencer is busy. Note that, whilst the

Control Write Sequencer is running a sequence (indicated by the WSEQ_BUSY bit), normal

read/write operations to the Control Registers cannot be supported. (The Write Sequencer registers

and the Software Reset register can still be accessed when the Sequencer is busy.) The index of the

current step in the Write Sequencer can be read from the WSEQ_CURRENT_INDEX field; this is an

indicator of the sequencer’s progress. On completion of a sequence, this field holds the index of the

last step within the last commanded sequence.

When the Write Sequencer reaches the end of a sequence, it asserts the WSEQ_EINT flag in

Interrupt Event on completion of the sequence. Note that the WSEQ_EINT flag is asserted to indicate

that the WSEQ is NOT Busy.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R108 (6Ch)

Write

Sequencer 0

WSEQ_ENA

Write Sequencer Enable.

0 = Disabled

1 = Enabled

R111 (6Fh)

Write

Sequencer 3

WSEQ_ABORT

Writing a 1 to this bit aborts the

current sequence and returns

control of the device back to the

serial control interface.

WSEQ_START

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.

5:0

WSEQ_START_

INDEX [5:0]

00_0000

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

R112 (70h)

Write

Sequencer 4

9:4

WSEQ_CURRE

NT_INDEX [5:0]

00_0000

Sequence Current Index (read only):

This is the location of the most

recently accessed command in the

write sequencer memory.

WSEQ_BUSY

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.

Table 85 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

86.

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.)

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