Specifications

ESS Technology, Inc. SAM0025A-062397 19
ES1879 DATA SHEET
PERIPHERAL INTERFACING
PRELIMINARY
DSP Digital Audio Playback
There are two choices for mixing the DSP digital audio
playback data with other audio sources. The audio data
can be mixed in the ES1879’s internal playback mixer or
external to the ES1879.
Mixing Internal to the ES1879
The DSP digital audio playback can be mixed within the
ES1879 playback mixer. To select this method, set the
Output Signal Control bits of the Mixer register 44h for
mixer output. To do this, program bits 6:4 of mixer register
44h to 1, 0, and 0, respectively. The volume of the DSP
digital audio playback is controlled by the DAC Play
Volume register 14h.
NOTE:
In Telegaming mode, register 14h also controls
the game-compatible first audio channel digital audio
playback. If independent mixer volume control of the
game-compatible and DSP digital audio data is
necessary, use the second method.
Mixing External to the ES1879
The second method is to use the FDXO output pin and mix
the DSP digital audio playback and the game-compatible
digital audio playback in an external audio mixer. To select
this method, set the Output Signal Control bits of Mixer
register 44h for mixer output except DAC playback. To do
this, program bits 6:4 of register 44h to 1, 0, and 1,
respectively. In addition, set bit 1 of Mixer register 46h high
to enable FDXO as an output when DSP serial mode is
enabled.
The volume of the DSP digital audio playback is controlled
within the DSP by scaling the data.
DSP Interface Serial Data Format
Figure 8 16-Bit Data, Positive Sync Pulse
Table 4 Digital Audio Mixing Methods in Serial Mode
To mix DSP and digital
audio...
...set the Output Signal
Control bits of register
44h to...
...and the volume of the DSP
digital audio playback is
controlled by...
In addition...
Bit 6 Bit 5 Bit 4
internal to the ES1879 1 0 0 DAC Play Volume register 14h N/A
external to the ES1879 1 0 1 scaling the data within the DSP set bit 1 of register 46h high.
DCLK
FS
DX
DR
Hi-Z
D15 D14 D13
D12 D1
D0
D15 D14 D13
D12 D1
D0
(MSB)
(MSB)