Rev. 1.60
106
August 20, 2019
Rev. 1.60
107
August 20, 2019
BS66F340/BS66F350/BS66F360/BS66F370
Touch A/D Flash MCU with LED Driver
BS66F340/BS66F350/BS66F360/BS66F370
Touch A/D Flash MCU with LED Driver
Timer Modules – TM
One of the most fundamental functions in any microcontroller devices is the ability to control and
measure time. To implement time related functions the device includes several Timer Modules,
generally 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
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 Compact, Standard and Periodic TM sections.
Introduction
These devices contain four TMs and each individual TM can be categorised as a certain type,
namely Compact Type TM, Standard Type TM or Periodic Type TM. Although similar in nature,
the different TM types vary in their feature complexity. The common features to all of the Compact,
Standard and Periodic TMs will be described in this section and the detailed operation regarding
each of the TM types will be described in separate sections. The main features and differences
between the three types of TMs are summarised in the accompanying table.
TM Function
CTM
STM
PTM
Timer/Counter
√
√
√
Input Capture
—
√
√
Compare Match Output
√
√
√
PWM Channels
1
1
1
Single Pulse Output
—
1
1
PWM Alignment
Edge
Edge
Edge
PWM Adjustment Period & Duty Duty or Period Duty or Period Duty or Period
TM Function Summary
TM Operation
The different types of TM 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 count-up counter whose value is then compared with the value of pre-programmed internal
comparators. When the free running count-up 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 xTMn
control registers, where "x" stands for C, S or P type TM and "n" stands for the specific TM serial
number. For STM and PTM there is no serial number "n" in the relevant pin or control bits since
there is only one STM and PTM respectively in the series of devices, The clock source can be a ratio
of the system clock, f
SYS
, or the internal high clock, f
H
, the f
SUB
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 for event counting.