Rev. 1.50
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HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
Periodic Type TM Operation Modes
The Periodic 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 TnM1 and TnM0 bits in the TMnC1 register.
Compare Match Output Mode
To select this mode, bits TnM1 and TnM0 in the TMnC1 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 TnCCLR 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 TnAF and TnPF interrupt request flags for Comparator A and
Comparator P respectively, will both be generated.
If the TnCCLR bit in the TMnC1 register is high then the counter will be cleared when a compare
match occurs from Comparator A. However, here only the TnAF interrupt request flag will be
generated even if the value of the CCRP bits is less than that of the CCRA registers. Therefore when
TnCCLR is high no TnPF 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 TMn output pin will change
state. The TMn output pin condition however only changes state when a TnAF interrupt request
flag is generated after a compare match occurs from Comparator A. The TnPF interrupt request flag,
generated from a compare match occurs from Comparator P, will have no effect on the TMn output
pin. The way in which the TMn output pin changes state are determined by the condition of the
TnIO1 and TnIO0 bits in the TMnC1 register. The TMn output pin can be selected using the TnIO1
and TnIO0 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 TMn output pin, which is setup after the
TnON bit changes from low to high, is setup using the TnOC bit. Note that if the TnIO1 and TnIO0
bits are zero then no pin change will take place.