Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

7.1.1 Serial Communication Channels A and B

Each communication channel provides a full-duplex asynchronous/synchronous receiver and transmitter using an operating frequency independently selected from a baud rate generator or an external clock input.

The transmitter accepts parallel data from the IMB, converts it to a serial bit stream, inserts the appropriate start, stop, and optional parity bits, then outputs a composite serial data stream on the channel transmitter serial data output (TxDx). Refer to 7.3.2.1 Transmitter for additional information.

The receiver accepts serial data on the channel receiver serial data input (RxDx), converts it to parallel format, checks for a start bit, stop bit, parity (if any), or break condition, and transfers the assembled character onto the IMB during read operations. Refer to 7.3.2.2 Receiver for additional information.

7.1.2 Baud Rate Generator Logic

The crystal oscillator operates directly from a 3.6864-MHz crystal connected across the X1 input and the X2 output or from an external clock of the same frequency connected to X1. The clock serves as the basic timing reference for the baud rate generator and other internal circuits.

The baud rate generator operates from the oscillator or external TTL clock input and is capable of generating 19 commonly used data communication baud rates ranging from 50 to 76.8k by producing internal clock outputs at 16 times the actual baud rate. Refer to 7.2 Serial Module Signal Definitions and 7.3.1 Baud Rate Generator for additional information.

The external clock input (SCLK), which bypasses the baud rate generator, provides a synchronous clock mode of operation when used as a divide-by-1 clock and an asynchronous clock mode when used as a divide-by-16 clock. The external clock input allows the user to use SCLK as the only clock source for the serial module if multiple baud rates are not required.

7.1.3 Internal Channel Control Logic

The serial module receives operation commands from the host and, in turn, issues appropriate operation signals to the internal serial module control logic. This mechanism allows the registers within the module to be accessed and various commands to be performed. Refer to 7.4 Register Description and Programming for additional information.

7.1.4 Interrupt Control Logic

Seven interrupt request (IRQ7–IRQ1) signals are provided to notify the CPU32 that an interrupt has occurred. These interrupts are described in 7.4 Register Description and Programming. The interrupt status register (ISR) is read by the CPU32 to determine all

MOTOROLAMC68340 USER’S MANUAL7- 3

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Motorola MC68340 manual Baud Rate Generator Logic, Internal Channel Control Logic, Interrupt Control Logic
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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.
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