TLC320AD535C-I Datasheet, PDF (21/43 Pages) Texas Instruments – DUAL CHANNEL VOICE/DATA CODEC

4 Serial Communications
DT_DOUT, DT_DIN, DT_SCLK, and DT_FS are the serial communication signals for the data channel serial port,
while VC_DOUT, VC_DIN, VC_SCLK, and VC_FS are the serial communication signals for the voice channel serial
port. The digital output data from the ADC is taken from DT_DOUT (or VC_DOUT). The digital input data for the DAC
is applied to DT_DIN (or VC_DIN). The synchronization clock for the serial communication data and the frame-sync
is taken from DT_SCLK and VC_SCLK for the data and voice channels, respectively. The frame-sync pulse which
signals the beginning of the ADC and DAC data transfer interval is taken from DT_FS and VC_FS for the data and
voice channels, respectively.
For signal data transmitted from the ADC or to the DAC, a primary serial communication is used. A secondary
communication reads or writes words to the control registers, which control both the options and the circuit
configurations of the device.
The purpose of primary and secondary communications is to allow conversion data and control data to be transferred
across the same serial port. A primary transfer is always dedicated to conversion data. A secondary transfer is used
to set up or read the control register values described in Appendix A, Programmable Register Set. A primary transfer
occurs for every conversion period. A secondary transfer occurs only when requested. Secondary serial
communication is requested by software - D0 of the primary data input to DT_DIN for the data channel serial port or
to VC_DIN for the voice channel serial port. A secondary request can be made for the voice channel without making
a secondary request for the data channel, or vice versa. Control registers 1 and 2 can only be written to or read from
the data channel serial port. Control registers 3 through 6 can only be written to or read from the voice channel serial
port.
4.1 Primary Serial Communication
Primary serial communication transmits and receives conversion signal data. The DAC word length is 15 bits and
the last bit of the primary 16-bit serial communication word is a control bit used to request secondary serial
communication. For all serial communications, the most significant bit is transferred first. For the 16-bit ADC word,
D15 is the most significant bit, and D0 is the least significant bit. For the 15-bit DAC data word in a primary
communication, D15 is the most significant bit, D1 is the least significant bit, and D0 is used for the secondary
communication request control. All digital data values are in 2s-complement data format. Refer to Figure 4–1.
XX_DIN
D15–D1
D0
D/A Data
A/D Data
Secondary
Communication Request
XX_DOUT
D15–D0
Figure 4–1. Primary Communication DIN and DOUT Data Format
4–1