TLC320AD535C-I_16 Datasheet, PDF (23/42 Pages) Texas Instruments – DUAL CHANNEL VOICE/DATA CODEC

4.2 Secondary Serial Communication
Secondary serial communication reads or writes 16-bit words that program both the options and the circuit
configurations of the device for either the voice channel or the data channel. Register programming always occurs
during secondary communication for that channel. 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.
Four primary and secondary communication cycles are required to program the four voice channel registers. In the
same manner, two primary and secondary communication cycles are necessary to program the data channel control
registers. If the default value for a particular register is desired, then the register addressing can be omitted during
secondary communications. The NOOP (no operation) command addresses a pseudo-register, register 0, and no
register programming takes place during this secondary communication. This can be used for either the data channel
or the voice channel serial port.
During a secondary communication, a register is written to or read from. When writing a value to a register, the
DT_DIN (or VC_DIN) line contains the value to be written. The data returned on DT_DOUT (or VC_DOUT) is 00h.
The method for requesting a secondary communication is by asserting the least significant bit (D0) of DT_DIN (or
VC_DIN) high as shown in Table 4–1.
Table 4–1. Least-Significant-Bit Control Function
CONTROL BIT D0
CONTROL BIT FUNCTION
0
No secondary communication request
1
Secondary communication request
Figure 4–4 shows the data format XX_DIN and XX_DOUT during secondary communication.
Don’t Care
XX_DIN
(Read)
D15
–– –– 1 D12 D11 D10 D9 D8
D7–D0
XX_DIN
(Write)
R/W
D15
Register Address
–– –– 0 D12 D11 D10 D9 D8
Register Data
D7–D0
XX_DOUT
(Read)
AII 0
D15–D8
Register Data
D7–D0
AII 0
XX_DOUT
(Write)
D15–D0
Figure 4–4. Secondary Communication DIN and DOUT Data Format
4–3