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Motorola MC68340 manual Freescale Semiconductor, Inc

Models: MC68340

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Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

OE—Overrun Error

1 = One or more characters in the received data stream have been lost. This bit is set upon receipt of a new character when the FIFO is full and a character is already in the shift register waiting for an empty FIFO position. When this occurs, the character in the receiver shift register and its break detect, framing error status, and parity error, if any, are lost. This bit is cleared by the reset error status command in the CR.

0 = No overrun has occurred.

TxEMP—Transmitter Empty

1 = The channel transmitter has underrun (both the transmitter holding register and transmitter shift registers are empty). This bit is set after transmission of the last stop bit of a character if there are no characters in the transmitter holding register awaiting transmission.

0 = The transmitter buffer is not empty. The transmitter holding register is loaded by the CPU32, or the transmitter is disabled. The transmitter is enabled/disabled by programming the TCx bits in the CR.

TxRDY—Transmitter Ready

This bit is duplicated in the ISR; bit 0 for channel A and bit 4 for channel B.

1 = The transmitter holding register is empty and ready to be loaded with a character. This bit is set when the character is transferred to the transmitter shift register. This bit is also set when the transmitter is first enabled. Characters loaded into the transmitter holding register while the transmitter is disabled are not transmitted and are lost.

0 = The transmitter holding register was loaded by the CPU32, or the transmitter is disabled.

FFULL—FIFO Full

1 = A character was transferred from the receiver shift register to the receiver FIFO and the transfer caused the FIFO to become full (all three FIFO holding register positions are occupied).

0 = The CPU32 has read the receiver buffer and one or more FIFO positions are available. Note that if there is a character in the receiver shift register because the FIFO is full, this character will be moved into the FIFO when a position is available, and the FIFO will remain full.

RxRDY—Receiver Ready

1 = A character has been received and is waiting in the FIFO to be read by the CPU32. This bit is set when a character is transferred from the receiver shift register to the FIFO.

0 = The CPU32 has read the receiver buffer, and no characters remain in the FIFO after this read.

MOTOROLAMC68340 USER’S MANUAL7- 25

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Motorola MC68340 manual Freescale Semiconductor, Inc
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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.