Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

currently active interrupt conditions. The interrupt enable register (IER) is programmable to mask any events that can cause an interrupt.

7.1.5 Comparison of Serial Module to MC68681

The serial module is code compatible with the MC68681 with some modifications. The following paragraphs describe the differences.

The programming model is slightly altered. The supervisor/user block in the MC68340 closely follows the MC68681. The supervisor-only block has the following changes:

•The interrupt vector register is moved from supervisor/user to supervisor only at a new address.

•MR2A and MR2B are moved from a hidden address location to a location at the bottom of the programming model.

The timer/counter is eliminated as well as all associated command and status registers.

Only certain output port pins are available.

There are no IP pins on the MC68340.

RxRTS and TxRTS are more automated on the MC68340.

The XTAL_RDY bit in the ISR should be polled until it is cleared to prevent an unstable frequency from being applied to the baud rate generator. The following code is an example:

if (XTAL_RDY==0) begin

write CSR end

else begin

wait jump loop

end

7.2 SERIAL MODULE SIGNAL DEFINITIONS

The following paragraphs contain a brief description of the serial module signals. Figure 7- 2 shows both the external and internal signal groups.

NOTE

The terms assertion and negation are used throughout this section to avoid confusion when dealing with a mixture of active-low and active-high signals. The term assert or assertion indicates that a signal is active or true, independent of the level represented by a high or low voltage. The term negate or negation indicates that a signal is inactive or false.

7- 4MC68340 USER’S MANUALMOTOROLA

For More Information On This Product,

Go to: www.freescale.com

Page 298 Page 300
Page 299
Image 299
Motorola MC68340 manual Comparison of Serial Module to MC68681, Serial Module Signal Definitions
Page 298 Page 300

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