Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

TxCTS—Transmitter Clear-to-Send

1 = Enables clear-to-send operation. The transmitter checks the state of the CTS≈ input each time it is ready to send a character. If CTS≈ is asserted, the character is transmitted. If CTS≈ is negated, the channel TxDx remains in the high state, and the transmission is delayed until CTS≈ is asserted. Changes in CTS≈ while a character is being transmitted do not affect transmission of that character. If both TxCTS and TxRTS are enabled, TxCTS controls the operation of the transmitter.

0 = The CTS≈ has no effect on the transmitter.

SB3–SB0—Stop-Bit Length Control

These bits select the length of the stop bit appended to the transmitted character as listed in Table 7-10. Stop-bit lengths of nine-sixteenth to two bits, in increments of one- sixteenth bit, are programmable for character lengths of six, seven, and eight bits. For a character length of five bits, one and one-sixteenth to two bits are programmable in increments of one-sixteenth bit. In all cases, the receiver only checks for a high condition at the center of the first stop-bit position—i.e., one bit time after the last data bit or after the parity bit, if parity is enabled.

If an external 1⋅ clock is used for the transmitter, MR2 bit 3 = 0 selects one stop bit, and MR2 bit 3 = 1 selects two stop bits for transmission.

Table 7-10. SBx Control Bits

SB3

SB2

SB1

SB0

Length 6-8 Bits

Length 5 Bits

0

0

0

0

0.563

1.063

0

0

0

1

0.625

1.125

0

0

1

0

0.688

1.188

0

0

1

1

0.750

1.250

0

1

0

0

0.813

1.313

0

1

0

1

0.875

1.375

0

1

1

0

0.938

1.438

0

1

1

1

1.000

1.500

1

0

0

0

1.563

1.563

1

0

0

1

1.625

1.625

1

0

1

0

1.688

1.688

1

0

1

1

1.750

1.750

1

1

0

0

1.813

1.813

1

1

0

1

1.875

1.875

1

1

1

0

1.938

1.938

1

1

1

1

2.000

2.000

MOTOROLAMC68340 USER’S MANUAL7- 39

For More Information On This Product,

Go to: www.freescale.com

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Motorola MC68340 manual SBx Control Bits, Length 6-8 Bits Length 5 Bits
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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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