Programming Notes - Epson 0C88832 Technical Manual

5 PERIPHERAL CIRCUITS AND THEIR OPERATION (Sound Generator)
BZSHT: 00FF44H•D5
Controls the one-shot buzzer output.
When "1" is written: Trigger
When "0" is written: No operation
When "1" is read:
When "0" is read:
Writing "1" into BZSHT causes the one-shot output
circuit to operate. The BZ (BZ) signal is output from
the R50 (R51) terminal. The buzzer output is
automatically turned OFF after the time set by
SHTPW has elapsed.
To output the BZ signal, "0" must always be set for
the data register R50D. The data register R51D does
not affect the BZ output.
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, "1" is read from BZSHTand
when the output is OFF, "0" is read.
At initial reset, BZSHT is set to "0" (ready).
The BZ signal can be output from R51 only when
the function is selected by mask option.
BZSTP: 00FF44H•D6
Forcibly stops the one-shot buzzer output.
When "1" is written: Forcibly stop
When "0" is written: No operation
Reading:
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".
108
Busy
Ready
Constantly "0"

5.12.7 Programming notes

(1) Since the buzzer signal is generated asynchro-
nously from the register BZON, when the signal
is turned ON or OFF by the register setting, a
hazard of a 1/2 cycle or less is generated.
(2) The SLP instruction has executed when the
buzzer signal output is in the enable status
(BZON = "1" or BZSHT = "1"), unstable clock is
output from the output terminal at the time of
return from the SLEEP status. Consequently,
when shifting to the SLEEP status, you should
set the buzzer signal output to the disable status
(BZON = BZSHT = "0") prior to executing the
SLP instruction.
(3) The one-shot output is only valid when the
normal buzzer output is OFF (BZON = "0")
status. The trigger is invalid during ON (BZON
= "1") status.
EPSON
E0C88832/88862 TECHNICAL MANUAL