7/20
MTU429B Revision 3.0
28/Oct/1999
MTU429B
(Preliminary)
MYSON
TECHNOLOGY
4.8 Predivider
The predivider is a 15-stage counter that uses PH0 as the clock source. The output of T-F/F is changed when
the input signal is changed from H to L. PH11~15 are reset to L when PLC 100H instruction is executed, or
power-on or external reset is used. When PH14 is changed from H to L, the HALT release signal is generated.
4.9 Alarm/Frequency/Melody
There is an 8-bit programmable counter and an 8-bit envelope control for alarm, frequency or melody output
from BZ/BZB.
The frequency counter can use software to select 1/2 duty, 1/3 duty or 1/4 duty drive mode.
4.10 INT Function
The INT pin can be selected by mask option as pull-high/pull-low or none, and rising edge/falling edge trigger.
4.11 Watchdog Timer
The watchdog timer automatically generates a device reset when it overflows. The interval of overflow is 8/64/
512 x PH10 (set by mask option). You can use software to enable and disable this function. The watchdog
enable flag will be disabled by power-on reset or reset-pin reset condition, but can not be disabled by watch-
dog reset itself.
4.12 HALT Function
The HALT instruction will disable all clocks except the predivider, timer, frequency counter, PWM, EL-light
generator and chattering clock to minimize the operating current.
4.13 STOP Function
The STOP instruction will disable all clocks to minimize the standby current, so only two external factors (INT,
IOA/IOC/S port, keyscan) can release the STOP condition.
R1
R2
ELP
ELC
EL-plane
D1
LIT
ELP
ELC
FREQ
1/2 DUTY FREQ
1/3 DUTY FREQ
1/4 DUTY FREQ
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