User guide

Page 12 Voice Recording & Playback Device
Revision 2.1
Recording Audio Data
When a
SET_REC
or
REC
command is issued the device will
be
gin sampling and storing the data present on ANAIN+ and
ANAIN- to the specified sector. After half the sector is used
the SAC pin will drop low to indicate that a new command can
be accepted. The device will accept commands as lon
g as
the SAC pin remains low. An
y command received after the
SAC returns hi
gh will be queued up and executed during the
next SAC c
ycle.
Fi
gure 13 shows a typical timing diagram and OpCode
se
quence for a recording operation. In this example the
SET_REC
command begins recording at the specified mem-
or
y location after T
arec
time has passed. Some time later the
low
going edge on the SAC pin alerts the host processor that
the first sector is nearl
y full. The host processor responds by
issuing a
REC
command before the SAC pin returns high.
The
REC
command instructs the APR6008 to continue
recordin
g in the sector immediately following the current sec-
tor. When the first sector is full the device automaticall
y jumps
to the next sector and returns the SAC si
gnal to a high state
to indicate that the second sector is now bein
g used. At this
point the host processor decides to issue a
STOP
command
durin
g the next SAC cycle. The device follows the
STOP
command and terminates recording after TS
arec
.The /BUSY
pin indicates when actual recordin
g is taking place.
Figure 13 Typical Recording Sequence
/CS
SCLK
DI
T
arec
TS
arec
SET_REC
STOP
SAC
ANAOUT+
ANAOUT-
ANAOUT
/BUSY
REC
APR6008