RCx Control Bits, Rba, Rbb | Motorola MC68340 manual

Freescale Semiconductor, Inc.

RC1–RC0—Receiver Commands

These bits select a single command as listed in Table 7-8.

Table 7-8. RCx Control Bits

RC1	RC0	Command
0	0	No Action Taken
0	1	Enable Receiver
1	0	Disable Receiver
1	1	Do Not Use

No Action Taken—The no action taken command causes the receiver to stay in its current mode. If the receiver is enabled, it remains enabled; if disabled, it remains disabled.

Receiver Enable—The receiver enable command enables operation of the channel's receiver. If the serial module is not in multidrop mode, this command also forces the receiver into the search-for-start-bit state. If the receiver is already enabled, this command has no effect.

Receiver Disable—The receiver disable command disables the receiver immediately. Any character being received is lost. The command has no effect on the receiver status bits or any other control register. If the serial module is programmed to operate in the local loopback mode or multidrop mode, the receiver operates even though this command is selected. If the receiver is already disabled, this command has no effect.

Do Not Use—Do not use this bit combination because the result is indeterminate.

7.4.1.8RECEIVER BUFFER (RB). The receiver buffer contains three receiver holding registers and a serial shift register. The channel's RxDx pin is connected to the serial shift register. The holding registers act as a FIFO. The CPU32 reads from the top of the stack while the receiver shifts and updates from the bottom of the stack when the shift register has been filled (see Figure 7-4). This register can only be read when the serial module is enabled (i.e., the STP bit in the MCR is cleared).

RBA, RBB						$713, $71B
7	6	5	4	3	2	1	0
RB7	RB6	RB5	RB4	RB3	RB2	RB1	RB0
RESET:
0	0	0	0	0	0	0	0
Read Only					Supervisor/User

RB7–RB0—These bits contain the character in the receiver buffer.

7.4.1.9TRANSMITTER BUFFER (TB). The transmitter buffer consists of two registers, the transmitter holding register and the transmitter shift register (see Figure 7-4). The holding register accepts characters from the bus master if the TxRDY bit in the channel's SR is set. A write to the transmitter buffer clears the TxRDY bit, inhibiting any more

7- 30MC68340 USER’S MANUALMOTOROLA

For More Information On This Product,

Go to: www.freescale.com

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.

Motorola MC68340 manual RCx Control Bits, Rba, Rbb

Models: MC68340

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

Table 7-8. RCx Control Bits

RBA, RBB

7- 30MC68340 USER’S MANUALMOTOROLA

MC68340 specifications