
S1C88348/317/316/308 TECHNICAL SOFTWARE
EPSON
II-131
APPENDIX C PROGRAMMING NOTES
(2) When the FOUT frequency is made "fOSC3/n",
you must turn on the OSC3 oscillation circuit
before outputting FOUT. A time interval of
several msec to several 10 msec, from the
turning ON of the OSC3 oscillation circuit to
until the oscillation stabilizes, is necessary, due
to the oscillation element that is used. Conse-
quently, if an abnormality occurs as the result of
an unstable FOUT signal being output exter-
nally, you should allow an adequate waiting
time after turning ON of the OSC3 oscillation,
before turning outputting FOUT. (The oscilla-
tion start time will vary somewhat depending
on the oscillator and on the externally attached
parts. Refer to the oscillation start time example
indicated in Chapter 7/Technical Hardware,
"ELECTRICAL CHARACTERISTICS".)
At initial reset, OSC3 oscillation circuit is set to
OFF state.
(3) The SLP instruction has executed when the
special output signals (TOUT, FOUT and BZ)
are in the enable status, an unstable clock is
output for the special output at the time of
return from the SLEEP state. Consequently,
when shifting to the SLEEP state, you should set
the special output signal to the disable status
prior to executing the SLP instruction.
I/O Port (P Port)
(1) When changing the port terminal from LOW
level to HIGH with the built-in pull-up resistor,
a delay in the waveform rise time will occur
depending on the time constant of the pull-up
resistor and the load capacitance of the termi-
nal. It is necessary to set an appropriate wait
time for introduction of an I/O port. Make this
wait time the amount of time or more calculated
by the following expression.
Wait time = RIN x (CIN + load capacitance on the
board) x 1.6 [sec]
RIN: Pull up resistance Max. value
CIN: Terminal capacitance Max. value
(2) When the analog comparator is used, "0" must
always be set for the I/O control registers
(IOC14–IOC15 or IOC16–IOC17, or both) of I/O
ports which will become input terminals.
Serial Interface
(1) Be sure to initialize the serial interface mode in
the transmitting/receiving disable status (TXEN
= RXEN = "0").
(2) Do not perform double trigger (writing "1") to
TXTRG (RXTRG) when the serial interface is in
the transmitting (receiving) operation. Further-
more, do not execute the SLP instruction. (When
executing the SLP instruction, set TXEN =
RXEN = "0".)
(3) In the clock synchronous mode, since one clock
line (SCLK) is shared for both transmitting and
receiving, transmitting and receiving cannot be
performed simultaneously. (Half duplex only is
possible in clock synchronous mode.)
Consequently, be sure not to write "1" to
RXTRG (TXTRG) when TXTRG (RXTRG) is "1".
(4) When a parity error or flaming error is gener-
ated during receiving in the asynchronous
mode, the receiving error interrupt factor flag
FSERR is set to "1" prior to the receiving
complete interrupt factor flag FSREC for the
time indicated in Table C.1. Consequently,
when an error is generated, you should reset the
receiving complete interrupt factor flag FSREC
to "0" by providing a wait time in error process-
ing routines and similar routines.
When an overrun error is generated, the
receiving complete interrupt factor flag FSREC
is not set to "1" and a receiving complete
interrupt is not generated.
Table C.1 Time difference between FSERR
and FSREC on error generation
Clock source
Time difference
fOSC3 / n
Programmable timer
1/2 cycles of fOSC3 / n
1 cycle of timer 1 underflow
(5) When the demultiplied signal of the OSC3
oscillation circuit is made the clock source, it is
necessary to turn the OSC3 oscillation ON, prior
to using the serial interface.
A time interval of several msec to several 10
msec, from the turning ON of the OSC3 oscilla-
tion circuit to until the oscillation stabilizes, is
necessary, due to the oscillation element that is
used. Consequently, you should allow an
adequate waiting time after turning ON of the
OSC3 oscillation, before starting transmitting/
receiving of serial interface. (The oscillation
start time will vary somewhat depending on the
oscillator and on the externally attached parts.
Refer to the oscillation start time example
indicated in Chapter 7/Technical Hardware,
"ELECTRICAL CHARACTERISTICS".)
At initial reset, the OSC3 oscillation circuit is set
to OFF status.