Specifications

ESS Technology, Inc. SAM0023-122898 43
ES1869 DATA SHEET
PROGRAMMING THE ES1869
PROGRAMMING THE ES1869
Identifying the ES1869
The ES1869 may be identified by reading mixer register
40h successively. It returns the following values on four
successive reads:
18h, 69h, A[11:0], A[7:0]
where 18h and 69h are data reads indicating the part
number (1869), and A[11:0] is the base address of the
configuration device.
Resetting the ES1869 by Software
The chip can be reset in either of two ways: hardware and
software reset. The hardware reset signal comes from the
ISA bus. Software reset is controlled by bit 0 of port
Audio_Base+6h.
To reset the ES1869 by software:
1. Write 1h to port Audio_Base+6h.
2. Delay a short period, for example, by reading back
Audio_Base+6h.
3. Write 0h to port Audio_Base+6h.
4. In a loop that lasts at least 1 millisecond, poll port
Audio_Base+Eh bit 7 for Read-Data-Available.
If bit 7 is high, read the byte from port Audio_Base+Ah.
Exit the loop if the content is 0AAh; otherwise, continue
polling.
Both hardware and software reset:
• Disable Extended mode.
• Reset the timer divider and filter registers for 8 kHz
sampling.
• Stop any DMA transaction in progress.
• Clear any active interrupt request.
• Disable voice input of mixer (see the D1h/ D3h
commands).
• Reset Compatibility mode and Extended mode DMA
counters to 2048 bytes.
• Set analog direction to be DAC, with the DAC value set to
mid-level.
• Set input volume for 8-bit recording with Automatic Gain
Control (AGC) to maximum.
• Set input volume for 16-bit recording to mid-range
In addition to performing actions on the above list, a
hardware reset resets all mixer registers to default values.
Modes of Operation
The ES1869 can operate the first audio channel in one of
two modes: Compatibility mode or Extended mode.
In both modes, a set of mixer and controller registers
enables application software to control the analog mixer,
record source, and output volume. Programming the
ES1869 Enhanced Mixer is described later in this
document. See “Programming the ES1869 Mixer” on
page52.
Compatibility Mode Description
The first mode, Compatibility mode, is compatible to the
Sound Blaster Pro. This is the default mode after reset. In
this mode, the ES1869 microcontroller is an intermediary
in all functions between the ISA bus and the CODEC. The
ES1869 microcontroller performs limited FIFO functions
using 64 bytes of internal memory.
Extended Mode Description
The ES1869 also supports an Extended mode of
operation. In this case, a 256-byte FIFO is used as an
intermediary between the ISA bus and the ADC and DAC
Control registers, and various Extended mode controller
registers are used for control. The ES1869 microcontroller
is mostly idle in this mode. DMA control is handled by
dedicated logic. Programming for Extended mode
operation requires accessing various control registers with
ES1869 commands. Some of these commands are also
useful for Compatibility mode, such as those that
configure DMA and IRQ channels.