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CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Telephone Function)
4.14.7 Flash
The flash function pulls down the DP terminal to Low level for a predetermined period of time to
temporarily restore the telephone to on-hook status. The flash time should be set to the FTS3–FTS0
register (FF12H). Table 4.14.7.1 lists the available flash time.
D3
0
0
0
0
0
0
0
0
Do not write "0" (0000B) to the FTS register because it may cause a malfunction.
At initial reset, the flash time is set to 563 msec.
Writing data to the FTS register just defines the flash time. The actual flash operation will be activated
when the FLASH bit (FF14H•D0) is set to "1".
Figure 4.14.7.1 shows a timing chart of the flash function.
HSON
(FF18H•D3)
Data bus
Write to TPS
(FF10H•D3)
Write to TCD
(FF17H)
Write to FLASH
(FF14H•D0)
DP
TONE
XRMUTE(R11)
XTMUTE(R10)
Interrupt
request
124
Table 4.14.7.1 Flash time selection
FTS
Flash time
D2
D1
D0
(msec)
0
0
0
Unavailable *
0
0
1
94
0
1
0
188
0
1
1
281
1
0
0
375
1
0
1
469
1
1
0
563
1
1
1
656
"0"
Flash
Pulse mode
"1"
"0'
"0"
"0"
t
t
FL
FLP
"0"
"1"
t
MH
"1"
Fig. 4.14.7.1 Flash execution timing chart
FTS
D3
D2
D1
D0
1
0
0
0
1
0
0
1
1
0
1
0
1
0
1
1
1
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
1
Flash
t
t
IDP
FL
t
:
FL
t
:
FLP
t
:
IDP
t
:
MH
EPSON
Flash time
(msec)
750
844
938
1031
1125
1219
1313
1406
2
Tone mode
t
FLP
Flash time
Flash pause time
Inter-digit pause time
Mute hold time
S1C63558 TECHNICAL MANUAL
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