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Rev. 1.21
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HT66F488/HT66F489
A/D Flash MCU with EEPROM
HT66F488/HT66F489
A/D Flash MCU with EEPROM
Standard Type TM Operating Modes
The Standard Type TM can operate in one of five operating modes, Compare Match Output Mode,
PWM Output Mode, Single Pulse Output Mode, Capture Input Mode or Timer/Counter Mode. The
operating mode is selected using the STM1 and STM0 bits in the STMC1 register.
Compare Match Output Mode
To select this mode, bits STM1 and STM0 in the STMC1 register, should be set to 00 respectively.
In this mode once the counter is enabled and running it can be cleared by three methods. These are
a counter overflow, a compare match from Comparator A and a compare match from Comparator P.
When the STCCLR bit is low, there are two ways in which the counter can be cleared. One is when
a compare match from Comparator P, the other is when the CCRP bits are all zero which allows the
counter to overflow. Here both STMAF and STMPF interrupt request flags for Comparator A and
Comparator P respectively, will both be generated.
If the STCCLR bit in the STMC1 register is high then the counter will be cleared when a compare
match occurs from Comparator A. However, here only the STMAF interrupt request flag will be
generated even if the value of the CCRP bits is less than that of the CCRA registers. Therefore when
STCCLR is high no STMPF interrupt request flag will be generated. In the Compare Match Output
Mode, the CCRA can not be set to “0”.
As the name of the mode suggests, after a comparison is made, the TM output pin, will change state.
The TM output pin condition however only changes state when a STMAF interrupt request flag is
generated after a compare match occurs from Comparator A. The STMPF interrupt request flag,
generated from a compare match occurs from Comparator P, will have no effect on the TM output
pin. The way in which the TM output pin changes state are determined by the condition of the
STIO1 and STIO0 bits in the STMC1 register. The TM output pin can be selected using the STIO1
and STIO0 bits to go high, to go low or to toggle from its present condition when a compare match
occurs from Comparator A. The initial condition of the TM output pin, which is setup after the
STON bit changes from low to high, is setup using the STOC bit. Note that if the STIO1 and STIO0
bits are zero then no pin change will take place.