Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

—Pulse-Width Measurement

—Period Measurement

—Event Counting

• Seven Maskable Interrupt Conditions Based on Programmable Events

8.1.1 Timer and Counter Functions

The term 'timer' is used to reference either timer 1 or timer 2, since the two are functionally equivalent.

The timer can perform virtually any application traditionally assigned to timers and counters. The timer can be used to generate timed events that are independent of the timing errors to which real-time programmed microprocessors are susceptible—for example, those of dynamic memory refreshing, DMA cycle steals, and interrupt servicing.

The timer has several functional areas: an 8-bit countdown prescaler, a 16-bit downcounter, timeout logic, compare logic, and clock selection logic. Figure 8-2 shows a functional diagram of the timer module.

8.1.1.1PRESCALER AND COUNTER. The counter can be driven directly by the selected clock or the prescaler output. Both the counter and prescaler are updated on the falling edge of the clock. During reset, the prescaler is set to $FF, and the counter is set to $0000. The counter is loaded with a programmed value on the first falling edge of the counter clock after the timer is enabled and again when a timeout occurs (counter reaches $0000). The prescaler and counter can be used as one 24-bit counter by enabling the prescaler and selecting the divide-by-256 prescaler output. Refer to 8.4 Register Description for additional information on how to program the timer.

8.1.1.2TIMEOUT DETECTION. Timeout is achieved when all 16 stages of the counter transition to zero, a counter value of $0000. Timeout is a defined counter event which triggers specific actions depending upon the programmed mode of operation. Refer to 8.3 Operating Modes for descriptions of the individual modes.

8.1.1.3COMPARATOR. The comparator block compares the value in the 16-bit compare register (COM) with the output of the 16-bit counter. When an exact match is detected, bits in the status register (SR) are set to indicate this condition. When in the input capture/output compare mode, a match is a defined counter event that can affect the output of the timer (TOUTx). Refer to 8.3.1 Input Capture/Output Compare for additional information on this mode.

8- 2MC68340 USER’S MANUALMOTOROLA

For More Information On This Product,

Go to: www.freescale.com

Page 345 Page 347
Page 346
Image 346
Motorola MC68340 manual Timer and Counter Functions
Page 345 Page 347

MC68340 specifications

The Motorola MC68340 is a highly integrated microprocessor that was introduced in the early 1990s. It belongs to the 68000 family of microprocessors and is designed to cater to the demands of embedded systems, particularly in telecommunications and networking applications. This chip represents a significant evolution in microprocessor technology by combining a microprocessor core with additional peripherals on a single chip, making it an attractive solution for engineers looking to design compact and efficient systems.

One of the key features of the MC68340 is its 32-bit architecture, which allows for significant processing power and data handling capabilities. This architecture enables the processor to handle larger data sizes and perform more complex calculations compared to its 16-bit predecessors. The MC68340 operates at clock speeds typically ranging from 16 MHz to 25 MHz. Its dual instruction pipeline enhances throughput, allowing for simultaneous instruction fetches and executions, which significantly boosts performance.

A notable characteristic of the MC68340 is the inclusion of integrated peripherals, which help reduce the overall component count in a system. Key integrated components include a memory management unit (MMU), a direct memory access (DMA) controller, and various communication interfaces such as serial ports. The memory management capabilities enhance the processor's ability to manage memory resources efficiently, enabling it to support multitasking environments commonly found in modern computing.

In terms of connectivity, the MC68340 features connections for both synchronous and asynchronous serial communication, making it well-suited for networking tasks. The processor supports a range of bus standards, including address and data buses, which facilitate seamless interaction with peripheral devices.

Another important aspect of the MC68340 is its flexibility. The processor supports multiple operating modes, including multiple CPU configurations and compatibility with the Motorola 68000 family, allowing for easier integration into existing systems.

Moreover, the MC68340 boasts low power consumption compared to many of its contemporaries, making it an excellent choice for battery-operated applications, enhancing its appeal in sectors like telecommunications, industrial control, and automotive systems. Its combination of performance, integration, versatility, and efficiency has secured the MC68340 a reputable position in the annals of embedded systems technology, proving to be a valuable asset for developers and engineers alike.
Top Page Image Contents