CS8416-CSZ datasheet(31/60 Pages) CIRRUS

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DS578F3

CS8416

10.2 Non-Audio Detection

An AES3 data stream may be used to convey non-audio data, thus it is important to know whether the in-

coming AES3 data stream is digital audio or not. This information is typically conveyed in channel status bit

1, which is extracted automatically by the CS8416. However, certain non-audio sources, such as AC-3™ or

MPEG encoders, may not adhere to this convention, and the bit may not be properly set. The CS8416 AES3

receiver can detect such non-audio data through the use of an autodetect module. The autodetect module

is similar to autodetect software used in Cirrus Logic DSPs.

If the AES3 stream contains sync codes in the proper format for IEC61937 or DTS® data transmission, an

internal AUTODETECT signal will be asserted. If the sync codes no longer appear after a certain amount

of time, autodetection will time-out and AUTODETECT will be de-asserted until another format is detected.

The AUDIO signal is the logical OR of AUTODETECT and the received channel status bit 1 (as decoded

according to the CHS bit in the Control1 register).

In Hardware Mode, AUDIO is output on pin 15. In Software Mode, AUDIO is available through the GPO pins.

If non-audio data is detected, the data is still processed exactly as if it were normal audio. The exception is

the use of de-emphasis auto-select feature which will bypass the de-emphasis filter if the input stream is

detected to be non-audio. It is up to the user to mute the outputs as required.

10.2.1 Format Detection

In Software Mode, the CS8416 can automatically detect various serial audio input formats. The Format

Detect Status register (0Bh) is used to indicate a detected format. The register will indicate if uncom-

pressed PCM data, IEC61937 data, DTS_LD data, DTS_CD data, or digital silence was detected. Addi-

tionally, the IEC61937 Pc/Pd burst preambles are available in registers 23h-26h. See the register

descriptions for more information.

10.3 Interrupts

The CS8416 has a comprehensive interrupt capability. The INT signal, available in Software Mode, indi-

cates when an interrupt condition has occurred and may be output on one of the GPOs. It can also be set

through bits INT[1:0] in the Control1 register (01h) to be active low, active high or active low with no active

pull-up transistor. This last mode is used for active low, wired-OR hook- ups, with multiple peripherals con-

nected to the microcontroller interrupt input pin.

Many conditions can cause an interrupt, as listed in the interrupt status register descriptions. Each source

may be masked off through mask register bits. In addition, each source may be set to rising edge, falling

edge, or level sensitive. Combined with the option of level sensitive or edge sensitive modes within the mi-

crocontroller, many different configurations are possible, depending on the needs of the equipment design-

er. Refer to the register descriptions for the Interrupt Mask (07h), Interrupt Mode MSB (08h), Interrupt Mode

LSB (09h), and Interrupt 1 Status (0Dh) registers

CS8416-CSZ 数据表(PDF) 31 Page - Cirrus Logic

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