Rev. 1.10
70
November 26, 2019
Rev. 1.10
71
November 26, 2019
HT68FB240
USB Low Speed Flash MCU
Compact Type TM Operating Modes
The Compact Type TM can operate in one of three operating
modes, Compare Match Output Mode,
PWM
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 occurs 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 the 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. If the CCRA bits are all
zero, the
counter will overflow when its reaches its maximum
10-bit, 3FF Hex, value, however here the TnAF
interrupt
request flag will not be generated.
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 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 TM
output
pin. The way in which the TM output pin changes
state are determined by the condition of the
TnIO1 and
TnIO0 bits in the TMnC1 register. The TM 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 TM 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.