
36
EPSON
S1C88848 TECHNICAL MANUAL
5 PERIPHERAL CIRCUITS AND THEIR OPERATION (Output Ports)
5.5.5 Special output
Besides normal DC output, each output port can
also be assigned special output function by
software (R27, R34, R50) or mask option (R26, R51)
as shown in Table 5.5.5.1.
Table 5.5.5.1 Special output ports
Output port
R26
R27
R34
R50
R51
Special output
TOUT output or REM output (mask option)
TOUT output (software selection)
FOUT output (software selection)
BZ output (software selection)
BZ output (mask option)
■ REM output (R26)
A mask option is provided so the R26 output port
terminal can be used for outputting a REM signal
(remote control carrier signal).
When REM output is selected, the R26 data register
is disconnected from the R26 terminal and can be
used as a general-purpose register that does not
affect the output.
The REM output is controlled using the remote
controller registers. Refer to Section 5.13, "Remote
Controller" for details.
■
_________
TOUT output (R27), TOUT output (R26)
In order for the S1C88848 to provide clock signal to
an external device, the R27 output port terminal can
be used to output a TOUT signal (clock output by
the programmable timer). Furthermore, the R26
_________
output port terminal can be used to output a TOUT
signal (TOUT inverted signal). The configuration of
the output ports R26 and R27 is shown in Figure
5.5.5.1.
Register R27D
Register PTOUT
R27 output
R26 output
Mask option
TOUT signal
REM signal
Register R26D
Fig. 5.5.5.1 Configuration of R26 and R27
_________
The output control for the TOUT (TOUT) signals is
done by the register PTOUT. When you set "1" for
_________
the PTOUT, the TOUT (TOUT) signal is output
from the R27 (R26) output port terminal. When "0"
is set, the R27 goes HIGH (VDD) and the R26 goes
LOW (VSS).
To output the TOUT signal, "1" must always be set
for the data register R27D.
_________
The data register R26D does not affect the TOUT
output.
The TOUT signal is generated from the
programmable timer underflow signal by halving
the frequency.
With respect to frequency control, see "5.10 Pro-
grammable Timer".
_________
Since the TOUT (TOUT) signal is generated asyn-
chronously from the register PTOUT, when the
signal is turned ON or OFF by setting the register, a
hazard of a 1/2 cycle or less is generated.
Figure 5.5.5.2 shows the output waveform of the
_________
TOUT (TOUT) signal.
PTOUT
TOUT output (R27)
TOUT output (R26) *
01
 when selected by mask option
________
Fig. 5.5.5.2 TOUT (TOUT) output waveform
■ FOUT output (R34)
In order for the S1C88848 to provide clock signal to
an external device, a FOUT signal (divided clock of
oscillation clock fOSC1 or fOSC3) can be output from
the output port terminal R34.
Figure 5.5.5.3 shows the configuration of output
port R34.
Register R34D
Register FOUTON
R34 output
FOUT signal
Fig. 5.5.5.3 Configuration of R34
The output control for the FOUT signal is done by
the register FOUTON. When you set "1" for the
FOUTON, the FOUT signal is output from the
output port terminal R34, when "0" is set, the HIGH
(VDD) level is output. At this time, "1" must always
be set for the data register R34D.
The frequency of the FOUT signal can be selected in
software by setting the registers FOUT0–FOUT2.
The frequency is selected any one from among
eight settings as shown in Table 5.5.5.2.
Table 5.5.5.2 FOUT frequency setting
FOUT2
FOUT frequency
0
1
fOSC1 / 1
fOSC1 / 2
fOSC1 / 4
fOSC1 / 8
fOSC3 / 1
fOSC3 / 2
fOSC3 / 4
fOSC3 / 8
FOUT1
0
1
0
1
FOUT0
0
1
0
1
0
1
0
1
fOSC1:
fOSC3:
OSC1 oscillation frequency
OSC3 oscillation frequency