Specifications

ESS Technology, Inc. SAM0025A-062397 23
ES1879 DATA SHEET
PERIPHERAL INTERFACING
PRELIMINARY
Table 9 shows the mode configurations when the
notebook unit is docked.
Docking Status
The ES1879 is either in docked or undocked state. The
state is determined by the DOCKED input, which is active-
high when docked.
In the undocked state, the XSC and XSD pins are driven
low. The XA[3:0] pins act as in mode 0 (differential
outputs), except they follow the AOUT_L/AOUT_R
outputs directly (i.e., after the master volume).
Playback Mode
The ES1879/ES978 design assumes that the active
speakers move from the portable to the expansion unit
when docked. Except when recording, expansion audio
sources are mixed in the expansion unit within the ES978
and played through speakers in the expansion unit. In
most cases, speakers within the portable unit are
programmed to be automatically muted when docked.
An exception is PC speaker beeps, which are always
heard in the portable, even when docked.
Each audio input can be programmed individually on how
to respond to a docking situation in one of the three ways:

As an analog input, such as mic, that remains in the
portable (ES1879) when docked and is muted in the
ES978.

As an analog input, such as line-in, that is disabled in the
ES1879 when docked and enabled in the ES978 when
docked, i.e., it is muted in the mixers in the ES1879 and
ES978.

As an analog input that is enabled in both the ES1879 and
ES978 mixers, and shares a common volume control.
(Note: An exception to sharing a common volume control
is allowed for the Mappable Volume register 5Dh; see
below).
The playback master volume is controlled through
software programming or by the up/down/mute switch
inputs. The latter method, called hardware volume control,
has active-low switch inputs in both the ES1879 and
ES978.
Record Mode
In record mode, the expansion audio bus is turned around,
and sound data is sent from the expansion unit ES978
chip to the ES1879 in the portable unit. The sound data
from the expansion unit can be mixed inside the ES1879
with local sources before recording. Because portable unit
sources (for example, FM) can be mixed into the
recording, it is not possible to do a record monitor function
through the expansion unit speakers (they are
automatically muted in record mode). It is possible for the
record monitor to use the speakers in the portable unit
(see bit 5 of Vendor-Defined Card-Level register 2Bh.)
The default situation for most applications is to have all
speakers muted during recording.
As in previous chips, one of four record sources can be
selected: Mic, Line, Aux A, or Mixer. When docked, the
ES1879 chip knows whether each resource is present in
the portable, the docking station, or both, and acts
accordingly.
Mono Full-Duplex Mode
In the ES1879, host-based software applications can use
full-duplex mode through two 8-bit DMA channels. The
restriction is that both record and playback are
monophonic.
The record channel can record from any analog input of
the ES1879, any analog input of the remote ES978, any
mix of the same, or from the FDXI input to the ES1879
when using the DSP serial port.
Stereo Full-Duplex Mode
In the ES1879, host-based software applications can use
stereo full-duplex mode through two 8-bit DMA channels.
The record channel can record from any analog input of
the ES1879, any analog input of the remote ES978, or any
mix of the same. It is possible to record from the FDXI
input to the ES1879 when using the DSP serial port, but
this data is monophonic.
No ES978 – Differential AOUT Mode
In some applications, there is no ES978 in the expansion
unit. In this case, XA[3:0] are used as differential outputs
that follow AOUT_L/AOUT_R and are intended to connect
to a differential-input power amplifier in the expansion unit.
This mode of operation is selected automatically
whenever the DOCKED input is zero. When DOCKED is
zero, XSC and XSD are high-impedance.
Power Management
Power management is controlled by bits 1:0 of Vendor-
Defined Card-Level register 2Dh. In previous
Audio
Drive
®
chips, power management was controlled via I/O port
Table 9 Docked Modes for Analog Audio
Mode XA0 XA1 XA2 XA3
0 -Left Play +Left Play -Right Play +Right Play
1 +Left
Record
-Left
Record
+Right
Record
-Right
Record
2 -Play +Play +Record -Record
3 Left Record Left Play Right Record Right Play