Advance Information
MT88L85
DESCRIPTION
BIT
b0
NAME
BURST
Burst Mode Select. A logic high de-activates burst mode; a logic low enables burst mode.
When activated, the digital code representing a DTMF signal (see Table 1) can be written
to the transmit register, which will result in a transmit DTMF tone burst and pause of equal
durations (typically 51 msec). Following the pause, the status register will be updated (b1 -
Transmit Data Register Empty), and an interrupt will occur if the interrupt mode has been
enabled.
When CP mode (control register A, b1) is enabled the normal tone burst and pause
durations are extended from a typical duration of 51 msec to 102 msec.
When BURST is high (de-activated) the transmit tone burst duration is determined by the
TOUT bit (control register A, b0).
b1
b2
RxEN
S/D
This bit enables the DTMF and Call Progress Tone receivers. A logic low enables both
circuits. A logic high deactivates and puts both receiver circuits into power down mode.
Single or Dual Tone Generation. A logic high selects the single tone output; a logic low
selects the dual tone (DTMF) output. The single tone generation function requires further
selection of either the row or column tones (low or high group) through the C/R bit (control
register B, b3).
Column or Row Tone Select. A logic high selects a column tone output; a logic low selects
a row tone output. This function is used in conjunction with the S/D bit (control register B,
b2).
Table 7
.
Control Register B Description
b3
C/R
BIT
b0
b1
NAME
IRQ
TRANSMIT DATA
REGISTER EMPTY
(BURST MODE ONLY)
RECEIVE DATA REGISTER
FULL
DELAYED STEERING
STATUS FLAG SET
Interrupt has occurred. Bit one
(b1) or bit two (b2) is set.
Pause duration has terminated
and transmitter is ready for new
data.
Valid data is in the Receive Data
Register.
Set upon the valid detection of
the absence of a DTMF signal.
STATUS FLAG CLEARED
Interrupt is inactive. Cleared after
Status Register is read.
Cleared after Status Register is
read or when in non-burst mode.
Cleared after Status Register is
read.
Cleared upon the detection of a
valid DTMF signal.
b2
b3
Table 8
.
Status Register Description
4-81
MITEL [ MITEL NETWORKS CORPORATION ]
