TLC320AD55 Datasheet, PDF (25/41 Pages) Texas Instruments – Sigma-Delta Analog Interface Circuit

3.5 Phone Mode Control
This function is provided for applications that need hardware control and monitor of external events. By
allowing the device to drive two FLAG terminals (set through the control 2 register), the host digital signal
processor (DSP) is capable of system control through the same serial port connection to the device. Along
with this control is the capability for monitoring the value of the ALT DATA terminal during a secondary
communication cycle. One application for this function is in monitoring ring detect or offhook detect from a
phone answering system. The two FLAG terminals allow response to these incoming control signals. Figure
3– 8 shows the timing associated with this operating mode.
Primary
Secondary
Primary
Secondary
Primary
FS
DOUT
(Secondary
Read)
ALT DATA
8 SCLKs
Register
Data
ALT DATA
DOUT
(Secondary
Write)
ÏÏÏÏÏÏÏÏÏÏ _{ALT DATA}
ÏÏÏÏÏ ÏÏÏÏ ÏÏÏÏ ÏÏÏÏÏÏÏ DIN
ÏÏÎÎÏÎÎÏÎÎÏÎÎÏÎÎÏÎÎÏÎÎÏ ÏÏÏÏ ÏÏÏÏÏÏÏ _FLAG0,
ÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏÏ ^{FLAG 1}
1 SCLK MAX
Set FLAG 0 = FLAG 1 = 1
Set FLAG 0 = FLAG 1 = 0
Figure 3– 8. Phone Mode Timing
3–7