MT8888C
RS0
0
0
1
1
WR
0
1
0
RD
1
0
1
FUNCTION
Write to Transmit Data Register
Read from Receive Data Register
Write to Control Register
Data Sheet
1
0
Read from Status Register
Table 3 - Internal Register Functions
b3
RSEL
b2
IRQ
b1
CP/DTMF
b0
TOUT
Table 4 - CRA Bit Positions
b3
C/R
b2
S/D
b1
TEST
b0
BURST
ENABLE
Table 5 - CRB Bit Positions
BIT
b0
b1
NAME
TOUT
CP/DTMF
DESCRIPTION
Tone Output Control. A logic high enables the tone output; a logic low turns the tone output
off. This bit controls all transmit tone functions.
Call Progress or DTMF Mode Select. A logic high enables the receive call progress mode;
a logic low enables DTMF mode. In DTMF mode the device is capable of receiving and
transmitting DTMF signals. In CP mode a rectangular wave representation of the received
tone signal will be present on the IRQ/CP output pin if IRQ has been enabled (control
register A, b2=1). In order to be detected, CP signals must be within the bandwidth
specified in the AC Electrical Characteristics for Call Progress.
Note: DTMF signals cannot be detected when CP mode is selected.
Interrupt Enable. A logic high enables the interrupt function; a logic low deactivates the
interrupt function. When IRQ is enabled and DTMF mode is selected (control register A,
b1=0), the IRQ/CP output pin will go low when either 1) a valid DTMF signal has been
received for a valid guard time duration, or 2) the transmitter is ready for more data (burst
mode only).
Register Select. A logic high selects control register B for the next write cycle to the control
register address. After writing to control register B, the following control register write cycle
will be directed to control register A.
Table 6 - Control Register A Description
b2
IRQ
b3
RSEL
13
Zarlink Semiconductor Inc.
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
