SLAS366 datasheet(23/58 Pages) TI2

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3–11

3.8

Smart Time Division Multiplexed Serial Port (SMARTDM)

The SMART time division multiplexed serial port (SMARTDM) uses the 4 wires of DOUT, DIN, SCLK, and FS to

transfer data into and out of the AIC14. The TLV320AIC14s SMARTDM supports three serial interface configurations

(see Table 3–2): stand-alone master, stand-alone slave, and master-slave cascade, employing a time division

multiplexed (TDM) scheme (a cascade of only-slaves is not supported). The SMARTDM allows for a serial connection

of up to 16 codecs to a single serial port. Data communication in these three serial interface configurations can be

carried out in either standard operation (default) or turbo operation. Each operation has two modes; programming

mode (default mode) and continuous data transfer mode. To switch from the programming mode to the continuous

data transfer mode, set bit D6 of control register 1 to 1, which resets after switching back to programming mode. The

TLV320AIC14 can be switched back from the continuous data transfer mode to the programming mode by setting

the LSB of the data on DIN to 1, only if the data format is (15+1), as selected by bit 0 of control register 1. The

SMARTDM automatically adjusts the number of time slots per frame sync (FS) to match the number of codecs in the

serial interface so that no time slot is wasted. Both the programming mode and the continuous data transfer mode

of the TLV320AIC14 are compatible with the TLV320AIC10. The TLV320AIC14 provides primary/secondary

communication and continuous data transfer with improvements and eliminates the requirements for hardware and

software requests for secondary communication as seen in the TLV320AIC10. The TLV320AIC14 continuous data

transfer mode now supports both master/slave stand-alone and cascade.

Table 3–2. Serial Interface Configurations

TLV320AIC14

M/S PIN

FSD PIN

COMMENTS

TLV320AIC14

CONNECTIONS

MASTER

SLAVE

MASTER

SLAVE

COMMENTS

Stand-alone master

High

Pull high

Stand-alone slave

Low

Pull-low

Master-slave cascade

High

Low

Connect to the next slave’s FS

(see Figure 3–7)

Last slave’s FSD pin is pulled high

Slave-slave cascade

Not supported

3.8.1

Programming Mode

In the programming mode, the FS signal starts the input/output data stream. Each period of FS contains two frames

as shown in Figures 3–13 and 3–14: data frame and control frame. The data frame contains data transmitted from

the ADC or to the DAC. The control frame contains data to program the AIC14s control registers. The SMARTDM

automatically sets the number of time slots per frame equal to 2 times the number of AIC14 codecs in the interface.

Each time slot contains 16-bit data. The SCLK is used to perform data transfer for the serial interface between the

AIC14 codecs and the DSP. The frequency of SCLK varies depending on the selected mode of serial interface. In

the stand-alone mode, there are 32 SCLKs (or two time slots) per sampling period. In the master-slave cascade

mode, the number of SLCKs equals 32x(Number of codecs in the cascade). The digital output data from the ADC

is taken from DOUT. The digital input data for the DAC is applied to DIN. The synchronization clock for the serial

communication data and the frame-sync is taken from SCLK. The frame-sync signal that starts the ADC and DAC

data transfer interval is taken from FS. The SMARTDM also provides a turbo mode, in which the FS’s frequency is

always the device’s sampling frequency, but SCLK is running at a much higher speed. Thus, there are more than 32

SCLKs per sampling period, in which the data frame and control frame occupy only the first 32 SCLKs from the falling

edge of the frame-sync FS (also see Section 3.6 for more details).

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