17.6 I/O Signals

Interrupts

17.4 Interrupts

These TIMB sources can generate interrupt requests:

•TIMB overflow flag (TOF) — The timer overflow flag (TOF) bit is set when the TIMB counter reaches the modulo value programmed in the TIMB counter modulo registers. The TIMB overflow interrupt enable bit, TOIE, enables TIMB overflow interrupt requests. TOF and TOIE are in the TIMB status and control registers.

•TIMB channel flags (CH1F–CH0F) — The CHxF bit is set when an input capture or output compare occurs on channel x. Channel x TIMB CPU interrupt requests are controlled by the channel x interrupt enable bit, CHxIE.

17.5 Wait Mode

The WAIT instruction puts the MCU in low-power standby mode.

The TIMB remains active after the execution of a WAIT instruction. In wait mode, the TIMB registers are not accessible by the CPU. Any enabled CPU interrupt request from the TIMB can bring the MCU out of wait mode.

If TIMB functions are not required during wait mode, reduce power consumption by stopping the TIMB before executing the WAIT instruction.

Port E shares three of its pins with the TIMB:

•PTE0/TCLKB is an external clock input to the TIMB prescaler.

•The two TIMB channel I/O pins are PTE1/TCH0B and PTE2/TCH1B.

17.6.1 TIMB Clock Pin (PTE0/TCLKB)

PTE0/TCLKB is an external clock input that can be the clock source for the TIMB counter instead of the prescaled internal bus clock. Select the PTE0/TCLKB input by writing 1s to the three prescaler select bits, PS[2:0]. See 17.7.1 TIMB Status and Control Register.

The maximum TCLK frequency is the least: 4 MHz or bus frequency ⎟ 2.

PTE0/TCLKB is available as a general-purpose I/O pin or ADC channel when not used as the TIMB clock input. When the PTE0/TCLKB pin is the TIMB clock input, it is an input regardless of the state of the DDRE0 bit in data direction register E.

17.6.2 TIMB Channel I/O Pins (PTE1/TCH0B–PTE2/TCH1B)

Each channel I/O pin is programmable independently as an input capture pin or an output compare pin. PTE1/TCH0B and PTE2/TCH1B can be configured as buffered output compare or buffered PWM pins.

MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1

Freescale Semiconductor

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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.

Freescale Semiconductor MC68HC908MR16, MC68HC908MR32 17.6 I/O Signals, Timb Clock Pin PTE0/TCLKB

Models: MC68HC908MR16 MC68HC908MR32