alc880 Realtek Semiconductor Corporation, alc880 Datasheet - Page 18

• Manufacturer Part Number: alc880
• Description: 7.1 Channel High Definition Audio Codec
• Manufacturer: Realtek Semiconductor Corporation

7.
7.1. Link Signals
The High Definition Audio (HDA) Link is the digital serial interface that connects the HDA codecs to the
HDA Controller. The HDA link protocol is controller synchronous, based on a 24.0MHz BIT-CLK sent
by the HDA controller. The input and output streams, including command and PCM data, are isochronous
with a 48kHz frame rate. Figure 4 shows the basic concept of the HDA link protocol.
7.1.1.
7.1 Channel High Definition Audio Codec
Previous Frame
SYNC
BCLK
RST#
SDO
SDI
BCLK
SYNC
RST#
Item
SDO
SDI
High Definition Audio Link Protocol
Signal Definitions
Description
24.0MHz bit clock sourced from the HDA controller and connecting to all codecs.
48kHz signal is used to synchronize input and output streams on the link. It is sourced from the HDA
controller and connects to all codecs.
Serial Data Output signal driven by the HDA controller to all codecs. Commands and data streams are
carried on SDO. The data rate is double-pumped; the controller drives data onto the SDO, the codec samples
data present on SDO with respect to each edge of BCLK. The HDA controller must support at least one
SDO. To extend outbound bandwidth, multiple SDOs may be supported.
Serial Data Input signal driven by the codec. This is point-to-point serial data from the codec to the HDA
controller. The controller must support at least one SDI. Up to a maximum of 15 SDI’s can be supported.
SDI is driven by the codec at each rising edge of BCLK, and sampled by the controller at each rising edge of
BCLK. SDI can be driven by the controller to initialize the codec’s ID.
Active low reset signal. Asserted to reset the codec to default power-on state. RST# is sourced from the
HDA controller and connects to all codecs.
Frame SYNC= 8 BCLK
Command Stream
(40-bit data)
Response Stream
(36-bit data)
T
frame_sync
Stream 'A' Data
Table 5.
Stream 'A' Tag
(Here 'A' = 5)
Figure 4.
= 20.833 µs (48KHz)
Link Signal Definitions
Stream
'C' Tag
HDA Link Protocol
8
(n bytes + 10-bit data)
Stream 'C' Data
Stream 'B' Tag
Stream 'B' Data
(Here 'B' = 6)
Track ID: JATR-1076-21
ALC880 Series
Next Frame
Datasheet
Rev. 1.4