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NT91214/15 Series
14
V1.0
6. One-key redialing
Off Hook D1 . . . Dn RD or On Hook
HFI
↓
D1 . . . Dn RD
If the dialing of D1 to Dn is finished, pressing
RD will cause the pulse dialing pin to go low for 1.67
seconds of break time and an 824 ms pause will
automatically be added. If the pulses of the number
dialed with D1 to Dn have not finished, the
pressing of the redial key will be ignored.
7. Flash dialing
Off Hook F D1 . . . Dn or On Hook
HFI
↓
F D1 . . . Dn
The flash keys emulate quick On-Off Hook operations.
Pressing the flash keys, F1 or F2 , will cause a
break of 96 ms or 640 ms (or, 297 ms or 640 ms,
depending on the model) on the
DP
output pin. Then, it
pauses for 824 ms and continues dialing the digits,
D1 to Dn . These digits are then stored in the redial
memory.
Each time the flash key is pressed, the redial memory
will
be cleared to store a new entry. In addition, the MODE
IN
status will be checked again for the setting of the
TONE/PULSE DIALING mode.
Similarly, to make sure that the IC is working properly,
new flash key inputs will be ignored as long as the digits
that were dialed have not finished.
Timing Waveforms
1. Timing Waveform in PULSE Mode:
Key Input
2
3
XMIT MUTE
HK or HFO
1
KT
T
KD
: debouncing time 21 ms
T
KTD
(23 ms), f = 437Hz
T
d
T
IDP
T
M
T
M
21ms
T
M
T
B
DP
Td:
T
IDP
:
T
KTO
: Key-in tone duration
T
KD
:
Debouncing time
Note: "
HK
" or "HFO" indicates chip works when hook switch "
HK
" goes low or Hands-Free control output HFO goes
high.
Delay time of Key valid to dialing signal out, typically 0ms
Inter-digit pause time