Rev. 1.71
66
April 11, 2017
Rev. 1.71
67
April 11, 2017
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
Timer Modules – TM
One of the most fundamental functions in any microcontroller device is the ability to control and
measure time. To implement time related functions the devices include several Timer Modules,
abbreviated to the name TM. The TMs are multi-purpose timing units and serve to provide
operations such as Timer/Counter, Input Capture, Compare Match Output and Single Pulse Output
as well as being the functional unit for the generation of PWM signals. Each of the TMs has two
individual interrupts. The addition of input and output pins for each TM ensures that users are
provided with timing units with a wide and flexible range of features.
The common features of the different TM types are described here with more detailed information
provided in the individual Standard and Periodic TM sections.
Introduction
The devices contain one or two TMs depending upon which device is selected with each TM having
a reference name of TM0~TM1. Each individual TM can be categorised as a certain type, namely
Standard Type TM or Periodic Type TM. Although similar in nature, the different TM types vary in
their feature complexity. The common features to the Standard and Periodic TMs will be described
in this section and the detailed operation will be described in corresponding sections. The main
features and differences between the two types of TMs are summarised in the accompanying table.
Function
STM
PTM
Timer/Counter
√
√
I/P Capture
√
√
Compare Match Output
√
√
PWM Channels
1
1
Single Pulse Output
1
1
PWM Alignment
Edge
Edge
PWM Adjustment Period & Duty
Duty or Period
Duty or Period
TM Function Summary
Device
TM0
TM1
HT66F002/HT66F0025
10-bit STM
—
HT66F003
10-bit STM
10-bit PTM
HT66F004
10-bit PTM
10-bit PTM
TM Name/Type Reference
TM Operation
The two different types of TMs offer a diverse range of functions, from simple timing operations
to PWM signal generation. The key to understanding how the TM operates is to see it in terms of
a free running counter whose value is then compared with the value of pre-programmed internal
comparators. When the free running counter has the same value as the pre-programmed comparator,
known as a compare match situation, a TM interrupt signal will be generated which can clear the
counter and perhaps also change the condition of the TM output pin. The internal TM counter is
driven by a user selectable clock source, which can be an internal clock or an external pin.
TM Clock Source
The clock source which drives the main counter in each TM can originate from various sources. The
selection of the required clock source is implemented using the xTnCK2~xTnCK0 bits in the xTM
control registers. The clock source can be a ratio of either the system clock f
SYS
or the internal high
clock f
H
, the f
TBC
clock source or the external xTCKn pin. The xTCKn pin clock source is used to
allow an external signal to drive the TM as an external clock source or for event counting.