Owner's manual

Table Of Contents
21-2 DS785UM1
Copyright 2007 Cirrus Logic
I
2
S Controller
EP93xx User’s Guide
2
1
2
1
21
The primary I
2
S port and the I
2
S clocks are multiplexed and can be assigned to either the
SSP pins or the Ac97 pins. The second and third I
2
S ports use the same clock pins as the
primary I
2
S port, but their serial output and input pins are multiplexed with EGPIO pins. The
second I
2
S port's serial output and serial input pins are multiplexed with EGPIO[4] and
EGPIO[5] respectively and are enabled by setting DeviceCfg.A1onG. The third I
2
S port's
serial output and serial input pins are multiplexed with EGPIO[6] and EGPIO[13] respectively
and are enabled by setting DeviceCfg.A2onG.
21.2 I
2
S Transmitter Channel Overview
Each I
2
S TX channel provides a single stereo I
2
S compliant output. The Transmit channel
can operate in master or slave mode. Data is transferred between the ARM Core and the I
2
S
controller via an interrupt based mechanism or DMA access. The ARM Core or host
processor must write words in multiples of 2 (that is, a left and right stereo pair). These words
are serially shifted out, timed with respect to the audio bit clock and word clock (SCLK and
LRCK) that are generated (see Chapter 5, “Clock Control” on page 5-4 for additional details).
The key features of the I
2
S transmitter are:
Three transmit data channels, master or slave mode.
Table 21-1. I
2
S Controller Input and Output Signals
Signal Name Type Description
lrck IN Left/right Word Audio slave clock.
sck IN Audio bit slave clock.
sdi0 IN Serial data for channel 0
sdi1 IN Serial data for channel 1
sdi2 IN Serial data for channel 2
sdo0 OUT Serial data output for TX channel 0
sdo1 OUT Serial data output for TX channel 1
sdo2 OUT Serial data output for TX channel 2
Table 21-2. Audio Interfaces Pin Assignment
Pin
Name
Normal Mode
I
2
S on SSP Mode I
2
S on AC'97 Mode
Pin Description Pin Description Pin Description
SCLK1 SPI Bit Clock
I
2
S Serial Clock
SPI Bit Clock
SFRM1 SPI Frame Clock
I
2
S Frame Clock
SPI Frame Clock
SSPRX1 SPI Serial Input
I
2
S Serial Input
SPI Serial Input
SSPTX1 SPI Serial Output
I
2
S Serial Output
SPI Serial Output
(No I
2
S Master Clock)
ARSTn AC'97 Reset AC'97 Reset
I
2
S Master Clock
ABITCLK AC'97 Bit Clock AC'97 Bit Clock
I
2
S Serial Clock
ASYNC AC'97 Frame Clock AC'97 Frame Clock
I
2
S Frame Clock
ASDI AC'97 Serial Input AC'97 Serial Input
I
2
S Serial Input
ASDO AC'97 Serial Output AC'97 Serial Output
I
2
S Serial Output