
PRODUCT SPECIFICATION
9-1
Audio Out
Chapter 9
by Gert Slavenburg, Santanu Dutta
9.1
AUDIO OUT OVERVIEW
The TM1300 Audio Out (AO) unit is new and contains
many features not available in the TM1100. It has up to
8 channels, and drives up to 4 external stereo D/A con-
verters through a flexible bit-serial connection.
It provides all signals to interface to high quality, low cost
oversampling D/A converters, including a precisely pro-
grammable oversampling D/A system clock. The AO unit
and external D/A’s together provide the following capa-
bilities:
Up to 8 channels of audio output.
16-bit or 32-bit samples per channel.
Programmable sampling rate.
Internal or external sampling clock source.
Autonomously reads processed audio data from
memory using double buffering (DMA).
Supports 16-bit mono and stereo PC standard mem-
ory data formats.
Supports little- and big-endian memory formats.
Provides control capability for highly integrated PC
codecs such as the AD1847, CS4218 or UAD1340.
9.2
NEW AND CHANGED FEATURES
Individual serial data outputs to each D/A
32-bit samples
No 8-bit sample support
No support for connecting several D/As to one serial data
output.
Table 9-1. AO unit external signals
Signal
Type
Description
AO_OSCLK
OUT
Over sampling clock. Can be pro-
grammed to emit any frequency up to 40
MHz, with sub-Hz resolution. Intended for
use as the 256 or 384fs oversampling
clock by the external D/A conversion sub-
system.
AO_SCK
IO
When AO is programmed to act as a
serial interface timing slave (RESET
default), AO_SCK acts as input. It
receives the serial clock from the
external audio D/A subsystem. The
clock is treated as fully asynchronous
to the TM1300 main clock.
When AO is programmed to act as
serial interface timing master,
AO_SCK acts as output. It drives the
serial clock for the external audio D/A
subsystem. Clock frequency is a pro-
grammable integral divide of the
AO_OSCLK frequency.
AO_SCK is limited to 22 MHz. The sam-
ple rate of valid samples embedded within
the serial stream is limited by the
AO_SCK maximum frequency and the
available highway bandwidth.
AO_WS
IO
When AO is programmed as the serial-
interface timing slave (RESET default),
AO_WS acts as an input. AO_WS is
sampled on the opposite AO_SCK
edge at which AO_SDx are asserted.
When AO is programmed as serial-
interface timing master, AO_WS acts
as an output. AO_WS is asserted on
the same AO_SCK edge as AO_SDx.
AO_WS is the word-select or frame-sync
signal from/to the external D/A sub-
system. Each audio channel receives 1
sample for every WS period.
AO_WS can be set to change on
AO_OSCLK positive or negative edges by
the CLOCK_EDGE bit.
AO_SD1
OUT
Serial data to stereo external audio D/A
subsystem. AO_SD1 can be set to
change on AO_OSCLK positive or nega-
tive edges by the CLOCK_EDGE bit.
AO_SD2
OUT
Serial data to stereo external audio D/A
subsystem. AO_SD2 can be set to
change on AO_OSCLK positive or nega-
tive edges by the CLOCK_EDGE bit.
AO_SD3
OUT
Serial data to stereo external audio D/A
subsystem. AO_SD3 can be set to
change on AO_OSCLK positive or nega-
tive edges by the CLOCK_EDGE bit.
AO_SD4
OUT
Serial data to stereo external audio D/A
subsystem. AO_SD4 can be set to
change on AO_OSCLK positive or nega-
tive edges by the CLOCK_EDGE bit.
Table 9-1. AO unit external signals
Signal
Type
Description