
I-70
EPSON
S1C88348/317/316/308 TECHNICAL HARDWARE
5 PERIPHERAL CIRCUITS AND THEIR OPERATION (Output Ports)
BZSHT: 00FF45HD5
Controls the one-shot buzzer output.
When "1" is written: Trigger
When "0" is written: No operation
When "1" is read:
Busy
When "0" is read:
Ready
Writing "1" into BZSHT causes the one-shot output
circuit to operate and the BZ signal to be output.
The buzzer output is automatically turned OFF
after the time set by SHTPW has elapsed. At this
time, "0" must always be set for the data register
R50D.
The one-shot output is only valid when the normal
buzzer output is OFF (BZON = "0") state. The
trigger is invalid during ON (BZON = "1") state.
When a re-trigger is assigned during a one-shot
output, the one-shot output time set with SHTPW is
measured again from that point. (time extension)
The operation status of the one-shot output circuit
can be confirmed by reading BZSHT, when the one-
shot output is ON, BZSHT reads "1" and when the
output is OFF, it reads "0".
At initial reset, BZSHT is set to "0" (ready).
BZSTP: 00FF45HD6
Forcibly stops the one-shot buzzer output.
When "1" is written: Forcibly stop
When "0" is written: No operation
Reading:
Constantly "0"
By writing "1" into BZSTP, the one-shot buzzer
output can be stopped prior to the elapsing of the
time set with SHTPW.
Writing "0" is invalid and writing "1" except during
one-shot output is also invalid.
When "1" is written to BZSHT and BZSTP simulta-
neously, BZSTP takes precedence and one-shot
output becomes stop status.
Since BZSTP is for writing only, during readout it is
constantly set to "0".
5.6.7 Programming notes
(1) Since the special output signals (CL, FR, TOUT,
FOUT and BZ) are generated asynchronously
from the output control registers (LCCLK,
LCFRM, PTOUT, FOUTON, BZON, BZSHT and
BZSTP), when the signals is turned ON or OFF
by the output control register settings, a hazard
of a 1/2 cycle or less is generated.
(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, "ELECTRICAL CHAR-
ACTERISTICS".)
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.