
S1C88848 TECHNICAL MANUAL
EPSON
113
5 PERIPHERAL CIRCUITS AND THEIR OPERATION (Remote Controller)
5.13.2 Mask option
R26 output port specification
R26 .......... ■
■ DC output
_________
■
■ TOUT output
■
■ REM output
The R26 output port can be configured for REM
_________
output, TOUT output (TOUT inverted output) or
general-purpose DC output by mask option.
Selecting REM output allows remote control carrier
output by the control described in Sections 5.13.3
through 5.13.5. Refer to Section 5.5, "Output Ports
_________
(R ports)", for how to control DC output and TOUT
output.
5.13.3 Carrier
The carrier is generated by the carrier generation
circuit using the OSC3 clock as the source clock.
The carrier cycle and duty ratio selections and the
carrier generation circuit ON/OFF control can be
done by software.
The control for the carrier is same procedure for
both the soft-timer mode and the hard-timer mode.
Perform the carrier settings before starting the
transmission in each mode.
The carrier cycle can be selected as a division ratio
of the OSC3 clock using the REM carrier cycle
setting register RCDIV. When "0" is written to
RCDIV, fOSC3/64 is selected and when "1" is
written, fOSC3/96 is selected.
The carrier duty ratio is set as shown in Table
5.13.3.1 using the REM carrier duty setting register
RCDUTY0–RCDUTY3. The selectable values and
range depend on the RCDIV value. When RCDIV =
"1", the remote controller does not output the REM
signal if RCDUTY is "1100" or more. When RCDIV
= "0", setting RCDUTY to "0100" or more selects the
same duty ratio as RCDUTY = "0011".
Carrier settings can be done even when the OSC3
oscillation circuit is in OFF status. Furthermore,
when these are set once, the set contents are
maintained until an initial reset is performed.
Note: The setting of RCDIV and the RCDUTY should
be done when the REM circuit is OFF (REMC
= "0") before starting remote transmission. If
changing the contents when the REM circuit is
ON, it may cause a malfunction.
Table 5.13.3.1 Carrier duty ratio
3
1
0
2
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
RCDIV = "1"
(fOSC3/96)
12/24
11/24
10/24
9/24
8/24
7/24
6/24
5/24
4/24
3/24
2/24
1/24
RCDIV = "0"
(fOSC3/64)
–
4/8
3/8
2/8
1/8
RCDUTY
Carrier duty ratio
The carrier generation circuit is turned ON and
OFF by the REM carrier ON/OFF register REMC.
By writing "1" to REMC, the carrier generation
circuit goes ON and generates the carrier. When
REMC is set to "0" by writing, the carrier generation
circuit goes OFF and the carrier generation stops.
The OSC3 clock is divided to generate the carrier.
Therefore, the OSC3 oscillation circuit must be ON
before starting remote output. Remote output
should be done when the OSC3 oscillation has
stabilized. Make sure that the OSC3 oscillation has
stabilized before starting a remote controller. After
turning the OSC3 oscillation circuit ON until the
oscillation stabilizes, an interval of several 100 sec
to several 10 msec is required. Therefore, you
should allow an adequate waiting time after
turning the OSC3 oscillation circuit ON before
starting a remote control output. (The oscillation
start time will vary somewhat depending on the
oscillator and on external parts. Refer to the
oscillation start time example indicated in Chapter
7, "ELECTRICAL CHARACTERISTICS".)
At initial reset, OSC3 oscillation circuit is set to ON
status.
Figure 5.13.3.1 shows the carrier waveform.
Note: Except when outputting the remote control
waveform, REMC should be fixed at "0" to
prevent outputting unnecessary waveforms
and to reduce current consumption. However
at initial reset, the REMC register is set to "1"
for initializing the carrier generation circuit.
The register must not be set to "0" until after
initialization (within 32 machine cycles).
OSC3 clock
64 clocks
96 clocks
1/64 division
2/8 duty
1/64 division
3/8 duty
1/96 division
6/24 duty
1/96 division
8/24 duty
Carrier
waveform
Fig. 5.13.3.1 Carrier waveform