CHAPTER 7 8-BIT PWM TIMER

Note:

Calculation example of intervals and square wave frequency

The following expression is the interval when the count clock cycle is set to 1 tINST and when an oscillation frequency (FCH) of 12.5 MHz and a PWM compare register (COMR) value of DDH (221) are set. Another expression is the frequency of the square wave output from the PWM pin that is operated continuously without changing the COMR register value.

However, the values are true when the maximum speed clock of the normal mode is selected (CS1, CS0 = 11B, 1 instruction cycle = 4/FCH) with the system clock control register (SYCC).

Interval

= (1 ⋅ 4/FCH ) ⋅ (COMR register value + 1)

=(4/12.5 MHz) ⋅ (221 + 1)

=71.0 ∝s

Output frequency = FCH / (1 ⋅ 8 ⋅ (COMR register value + 1))

=12.5 MHz/ (8 ⋅ (221 + 1)) 7.04 kHz

■PWM Timer Functions

The PWM timer functions have an 8-bit resolution and can control the "H" level width and "L" level width of one cycle.

Because the resolution is 1/256, a pulse can be output at a duty ratio of 0 to 99.6%.

The frequency of the PWM wave can be selected from four types.

The low-pass filter can be connected to the output and used as the D/A converter.

Table 7.1-2shows the frequency of the PWM wave that can be set by PWM timer functions. Figure 7.1-1is a configuration example of the D/A converter.

Table 7.1-2 Frequencies of the PWM Wave that can be Set by the PWM Timer Functions

 

1

2

3

 

 

 

 

 

 

 

4

 

 

 

 

 

 

Internal clock

 

 

 

Output of an 8/16-bit capture timer/counter

 

Count clock cycle

1tINST

16tINST

64tINST

22t

INST

to

26t

INST

to

210t

INST

to

1tEXT to

210tINST

214tINST

218tINST

28tEXT

 

 

 

 

 

 

 

 

210t

INST

to

214t

to

218t

INST

to

28t

to

PWM wave cycle

28tINST

212tINST

214tINST

 

 

 

 

INST

 

 

 

EXT

 

218tINST

222tINST

226tINST

216tEXT

 

 

 

 

tINST: Instruction cycle (Affected by the clock mode and others.)

tEXT: Output frequency of an 8/16-bit capture timer

137

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Fujitsu F202RA, MB89202 manual PWM Timer Functions, Internal clock Output of an 8/16-bit capture timer/counter, 137
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F202RA, MB89202 specifications

The Fujitsu MB89202 and F202RA microcontrollers are part of the 16-bit microcontroller family, renowned for their robust performance and versatility in a variety of embedded system applications. These devices are tailored for high-efficiency operation across diverse industries, including automotive, consumer electronics, and industrial automation.

One of the main features of the MB89202 is its powerful CPU core, which operates at a clock speed of up to 20 MHz. This enables the microcontroller to perform complex calculations and consumer-grade applications seamlessly. The architecture is designed to handle multiple tasks effectively, making it suitable for real-time operations.

Memory capacity is a vital characteristic of the MB89202, featuring on-chip RAM and ROM configurations. The microcontroller can accommodate different memory variants, providing developers with flexibility in memory allocation based on their application requirements. This adaptability facilitates applications ranging from simple control systems to complex data processing tasks.

The F202RA variant extends the capabilities of the MB89202 by integrating advanced peripheral functions. It includes built-in timers, A/D converters, and serial communication interfaces, which are essential for interfacing with other hardware components or sensors. The availability of these peripherals reduces the need for additional external circuits, thus contributing to a more compact and cost-effective design.

In terms of power management, the MB89202 series employs advanced power-saving technologies. The microcontroller offers various low-power modes, enabling devices to conserve energy during idle times, making it highly suitable for battery-operated applications. This characteristic not only enhances the efficiency of devices but also extends their operational lifespan.

Moreover, the Fujitsu MB89202 series incorporates robust protection features, including watchdog timers and failure detection mechanisms. These safety features ensure reliable operation in critical systems, making them a preferred choice in applications where failure is not an option.

The MB89202 and F202RA microcontrollers also support a range of development tools and environments, including integrated development environments (IDEs) and software libraries, which facilitate rapid application development. With these tools, developers can efficiently prototype, debug, and optimize their applications.

In summary, the Fujitsu MB89202 and F202RA microcontrollers stand out with their efficient performance, extensive memory options, integrated peripherals, and power-saving capabilities, making them ideal for a wide array of embedded applications. Their reliability and robustness further enhance their attractiveness for designers seeking advanced microcontroller solutions.
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