TCC76 datasheet(73/259 Pages) ETC2

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TCC76x

Specification Rev. 0.07

February 23, 2005

32-bit RISC Microprocessor for Digital Media Player

DAI & CDIF

Preliminary

4-1

4 DAI & CDIF

4.1 DAI (Digital Audio Interface)

The block diagram of DAI is shown in Figure 4.1.

The TCC76x provides digital audio interface that complies with IIS (Inter-IC Sound). The DAI

has five input/output pins for IIS interface, MCLK, BCLK, LRCK, DAI and DAO. All DAI

input/output pins are multiplexed with GPIO pins; GPIO_B<21:25>.

The MCLK is the system clock pin that is used for CODEC system clock. In master mode, the

MCLK can be generated from clock generator in which that is known as a DCLK, or fed from

the outside of chip in slave mode. The DAI can process 256fs, 384fs and 512fs as a system clock.

256fs means that the system clock has 256 times of sampling frequency (fs).

The BCLK is the serial bit clock for IIS data exchange. The DAI can generate 64fs, 48fs and

32fs by dividing a system clock. The polarity of BCLK can be programmed. That is, the serial

bit can be stable either rising edge of BCLK or falling edge of BCLK.

The LRCK is the frame clock for the stereo audio channel Left and Right. The frequency of

LRCK is known as the “fs” – sampling frequency. Generally, for audio application such as

MP3 Player and CD player, the fs can be set to 8kHz, 16kHz, 11.05kHz, 24kHz, 32kHz,

44.1kHz and 48kHz. For supporting the wide range of sampling frequency in audio application,

the DCO function is very useful to generate a system clock. Refer the chapter of clock generator

for detail information.

All three clocks (MCLK, BCLK, LRCK) are selectable as master or slave.

The DAI, DAO are the serial data input output pins respectively.

The DAI has two 8-word input/output buffers. It has a banked buffer structure so that one side of

buffer is receiving/transmitting data while the other side of that can be read/written through the

DADI_XX/DADO_XX registers. The maximum data word size is 24 bit. Data is justified to

MSB of 32bits and zeros are padded to LSB.

There are two types of interrupt from IIS; transmit done interrupt, receive done interrupt. The

transmit-done interrupt is generated when the 8 words are transferred successfully in the output

buffer. At this interrupt, user should fill another 8 more words into the other part of the output

buffer in the interrupt service routine (ISR). In this ISR routine, 8 consecutive stores of word

data to the DADO registers are needed. The receive-done interrupt is generated when the 8 words

are received successfully in the input buffer. At this interrupt, user should read 8 received words

from the input buffer using 8 consecutive load instructions from the DADI registers.

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