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118 EPSON S1C63558 TECHNICAL MANUAL
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Telephone Function)
t
TD
t
MH
t
TD
:
t
TIP
:
t
MH
:
"0"
t
TIP
t
TIP
t
TIP
Tone duration time
Tone inter-digit pause time
Mute hold time
"0"
"0"
"0"
HSON
(FF18H•D3)
Data bus
Write to TCD
(FF17H)
DP
TONE
XRMUTE(R11)
XTMUTE(R10)
Interrupt
request
"1"
"1"
5897
Fig. 4.14.4.2 Tone output timing chart
By writing data to the TCD register, the TONE terminal outputs the specified tone signal. At the same
time, the XTMUTE (R10) terminal goes Low level.
The minimum tone duration time (tTD) is 94 msec and can be prolonged using the CTO register
(FF16H•D3). When the CTO register is set to "1" before writing data to the TCD register, the tone output
continues until "0" is written to the CTO register. However the tone signal will be output for 94 msec even
if the CTO register is set to "0" before 94 msec duration time has passed. The tone duration time when the
CTO register is set to "0" is 94 msec.
When the tone signal has been output completely, the TONE terminal returns to Low level, then a 94
msec of inter-digit pause will be inserted.
An interrupt occurs when the inter-digit pause time has passed. It allows transmission of the next tone.
The XTMUTE (R10) terminal keeps on Low level for 4 msec of mute hold time (
tMH) after the inter-digit
pause is released. If the next tone output does not start in this period, the XTMUTE (R10) terminal returns
to High level. When the next tone output starts in the mute hold period, the XTMUTE (R10) terminal will
stay in Low level.
Note that the CTMUT register (FF18H•D0) and CRMUT register (FF18H•D1) must be set to "1" when the
above mute function (XTMUTE and XRMUTE control) is used.