Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

7.2.3 External Input (SCLK)

This input can be used as the clock input for channel A and/or channel B and is programmable in the clock-select registers (CSR). When used as the receiver clock, received data is sampled on the rising edge of the clock. When used as the transmitter clock, data is output on the falling edge of the clock. If this input is not used, it must be connected to VCC or GND.

7.2.4 Channel A Transmitter Serial Data Output (TxDA)

This signal is the transmitter serial data output for channel A. The output is held high ('mark' condition) when the transmitter is disabled, idle, or operating in the local loopback mode. Data is shifted out on this signal on the falling edge of the clock source, with the least significant bit transmitted first.

7.2.5 Channel A Receiver Serial Data Input (RxDA)

This signal is the receiver serial data input for channel A. Data received on this signal is sampled on the rising edge of the clock source, with the least significant bit received first.

7.2.6 Channel B Transmitter Serial Data Output (TxDB)

This signal is the transmitter serial data output for channel B. The output is held high ('mark' condition) when the transmitter is disabled, idle, or operating in the local loopback mode. Data is shifted out on this signal at the falling edge of the clock source, with the least significant bit transmitted first.

7.2.7 Channel B Receiver Serial Data Input (RxDB)

This signal is the receiver serial data input for channel B. Data on this signal is sampled on the rising edge of the clock source, with the least significant bit received first.

7.2.8 Channel A Request-To-Send (RTSA)

This active-low output signal is programmable as the channel A request-to-send or as a dedicated parallel output.

7.2.8.1RTSA. When used for this function, this signal can be programmed to be

automatically negated and asserted by either the receiver or transmitter. When connected to the clear-to-send (CTS≈) input of a transmitter, this signal can be used to control serial data flow.

7.2.8.2OP0. When used for this function, this output is controlled by bit 0 in the output port data register (OP).

7.2.9 Channel B Request-To-Send (RTSB)

This active-low output signal is programmable as the channel B request-to-send or as a dedicated parallel output.

7- 6MC68340 USER’S MANUALMOTOROLA

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Motorola MC68340 manual Freescale Semiconductor, Inc External Input Sclk, Channel a Transmitter Serial Data Output TxDA
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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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