Rainbow Electronics APR6016 - Manual (Page 13)

Preliminary
APR6016 Data Sheet
Voice Recording & Playback Device Page 13
Revision 1.0
Playing Back Audio Data
When a SET_PLAY or PLAY command is issued the device
will begin sampling the data in the specified sector and pro-
duce a resultant output on the AUDOUT, ANAOUT-, and
ANAOUT+ pins. 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 long as the SAC pin
remains low. Any command received after the SAC returns
high will be queued up and executed during the next SAC
cycle.
Figure 14 shows a typical timing diagram and OpCode
sequence for a playback operation. The
SET_PLAY com-
mand begins playback at the specified memory location after
T
aplay
time has passed. Some time later the low going edge
on the SAC pin alerts the host processor that half of the first
sector has been played back. The host processor responds
by issuing a
PLAY command during the SAC low time. The
PLAY command instructs the APR6016 to continue playback
of the sector immediately following the current sector. When
the first sector has been played back the device jumps to the
next sector and returns the SAC signal to a high state to indi-
cate that the second sector is now being played. At this point
the host processor decides to issue a
STOP command during
the next available SAC low time. The device follows the
STOP command and terminates playback after TS
aplay
. The
/BUSY pin indicates when actual playback is taking place.
Figure 14 Typical Playback Sequence
Handshaking signals
Several signals are included in the device that allow for hand-
shaking. These signals can simplify message management
significantly depending on the message management
scheme used.
The /INT signal can be used to generate interrupts to the pro-
cessor when attention is required by the APR6016 This pin is
normally high and goes low when an interrupt is requested.
An interrupt is generated whenever a EOD or Overflow
occurs.
The SAC signal is used to determine when the device is
nearing the end of the current memory segment during either
a record, play or forward operation. The SAC signal is in a
normally high state. The signal goes low after half the cur-
rently active segment has been played or recorded. The sig-
nal returns to a high state after the entire segment has been
played or recorded. The microprocessor should sense the
low edge of the SAC signal as an indicator that the next seg-
/CS
SCLK
DI
T
aplay
TS
aplay
SET_PLAY STOP
SAC
ANAOUT+
ANAOUT-
ANAOUT
/BUSY
Note: Command timing is not to scale
PLAY