Functional Description

Addr.

Register Name

 

Bit 7

6

 

5

4

3

2

1

Bit 0

 

TIMA Channel 2 Register High

Read:

 

 

 

 

 

 

 

 

 

 

Bit 15

14

 

13

12

11

10

9

Bit 8

 

 

 

$001A

(TACH2H)

Write:

 

 

 

 

 

 

 

 

 

 

 

See page 232.

 

 

 

 

 

 

 

 

 

 

 

Reset:

 

 

 

 

Indeterminate after reset

 

 

 

 

 

 

 

 

 

 

 

 

 

TIMA Channel 2 Register Low

Read:

 

 

 

 

 

 

 

 

 

 

Bit 7

6

 

5

4

3

2

1

Bit 0

 

 

 

$001B

(TACH2L)

Write:

 

 

 

 

 

 

 

 

 

 

 

See page 232.

 

 

 

 

 

 

 

 

 

 

 

Reset:

 

 

 

 

Indeterminate after reset

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TIMA Channel 3 Status/Control

Read:

CH3F

CH3IE

 

0

MS3A

ELS3B

ELS3A

TOV3

CH3MAX

 

 

 

 

 

$001C

Register (TASC3)

Write:

0

 

R

 

 

 

 

 

 

 

 

See page 229.

 

 

 

 

 

 

 

 

 

 

 

Reset:

0

0

 

0

0

0

0

0

0

 

 

 

 

TIMA Channel 3 Register High

Read:

 

 

 

 

 

 

 

 

 

 

Bit 15

14

 

13

12

11

10

9

Bit 8

 

 

 

$001D

(TACH3H)

Write:

 

 

 

 

 

 

 

 

 

 

 

See page 232.

 

 

 

 

 

 

 

 

 

 

 

Reset:

 

 

 

 

Indeterminate after reset

 

 

 

 

 

 

 

 

 

 

 

 

 

TIMA Channel 3 Register Low

Read:

 

 

 

 

 

 

 

 

 

 

Bit 7

6

 

5

4

3

2

1

Bit 0

 

 

 

$001E

(TACH3L)

Write:

 

 

 

 

 

 

 

 

 

 

 

See page 232.

 

 

 

 

 

 

 

 

 

 

 

Reset:

 

 

 

 

Indeterminate after reset

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

= Reserved

 

 

 

 

 

 

 

 

 

R

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 16-3. TIM I/O Register Summary (Continued)

16.3 Functional Description

Figure 16-2shows the TIMA structure. The central component of the TIMA is the 16-bit TIMA counter that can operate as a free-running counter or a modulo up-counter. The TIMA counter provides the timing reference for the input capture and output compare functions. The TIMA counter modulo registers, TAMODH–TAMODL, control the modulo value of the TIMA counter. Software can read the TIMA counter value at any time without affecting the counting sequence.

The four TIMA channels are programmable independently as input capture or output compare channels.

16.3.1 TIMA Counter Prescaler

The TIMA clock source can be one of the seven prescaler outputs or the TIMA clock pin, PTE3/TCLKA. The prescaler generates seven clock rates from the internal bus clock. The prescaler select bits, PS[2:0], in the TIMA status and control register select the TIMA clock source.

16.3.2 Input Capture

An input capture function has three basic parts:

1.Edge select logic

2.Input capture latch

3.16-bit counter

Two 8-bit registers, which make up the 16-bit input capture register, are used to latch the value of the free-running counter after the corresponding input capture edge detector senses a defined transition. The polarity of the active edge is programmable. The level transition which triggers the counter transfer is defined by the corresponding input edge bits (ELSxB and ELSxA in TASC0–TASC3 control registers with

MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1

Freescale Semiconductor

219

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Freescale Semiconductor MC68HC908MR16, MC68HC908MR32 manual Tima Counter Prescaler, Input Capture
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MC68HC908MR16, MC68HC908MR32 specifications

Freescale Semiconductor's MC68HC908MR32 and MC68HC908MR16 microcontrollers are part of the popular HC08 family, designed primarily for embedded applications. These microcontrollers are particularly favored in automotive, industrial, and consumer product sectors due to their reliability and versatility.

One of the standout features of the MC68HC908MR series is its CMOS technology, which enhances performance while minimizing power consumption. This makes these microcontrollers suitable for battery-operated devices. They operate at a maximum clock frequency of 2 MHz and offer a 16-bit architecture, providing a solid balance between processing power and efficiency.

The MC68HC908MR32 variant is equipped with 32KB of flash memory, which allows for the storage of complex programs and extensive data handling. In contrast, the MC68HC908MR16 features 16KB of flash memory, making it ideal for simpler applications. Both microcontrollers also come with 1KB of RAM, enabling efficient data processing and real-time operations.

Another significant characteristic of these microcontrollers is their integrated peripherals. They come with multiple input/output (I/O) pins, which allow for connectivity with various sensors and actuators. The built-in timer systems offer precise timing control for automotive and industrial applications, while the Analog-to-Digital Converter (ADC) provides essential conversion capabilities for various analog signals.

For communication purposes, the MC68HC908MR series includes a serial communication interface, enabling easy integration with other devices and systems. This versatility facilitates the development of complex systems that require interaction with external components.

Security is another crucial aspect of these microcontrollers. They have built-in fail-safe mechanisms to ensure reliable operation under various conditions, making them suitable for critical systems. Additionally, their robust architecture helps to safeguard against potential disruptions or attacks.

In summary, Freescale Semiconductor's MC68HC908MR32 and MC68HC908MR16 microcontrollers are key players in the embedded systems landscape. Their blend of power efficiency, integrated features, and scalability ensures they remain relevant for a wide array of applications, making them a favored choice among engineers and developers looking for dependable solutions in a competitive market.
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