MT8885 Mitel Networks Corporation, MT8885 Datasheet - Page 10

• Manufacturer Part Number: MT8885
• Description: Integrated DTMFTransceiver with Power Down & Adaptive Micro Interface
• Manufacturer: Mitel Networks Corporation

MT8885
4-60
RS0
BIT
b0
b1
b2
b3
0
0
1
1
RSEL
C/R
b3
b3
Motorola
Table 3. Internal Register Functions
CP/DTMF
R/W
NAME
TOUT
RSEL
0
1
0
1
IRQ
Table 4. CRA Bit Positions
Table 5. CRB Bit Positions
S/D
IRQ
b2
b2
WR
0
1
0
1
Intel
Tone Output Control. A logic high enables the tone output; a logic low turns the tone output
off and places the complete DTMF transmitter circuit in power down mode. 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 retangular 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 de-activates 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.
RD
1
0
1
0
CP/DTMF
TEST
Write to Transmit
Data Register
Read from Receive
Data Register
Write to Control Register
Read from Status Register
b1
b1
Table 6. Control Register A Description
FUNCTION
ENABLE
BURST
TOUT
b0
b0
DESCRIPTION
Advance Information