Motorola MC68340 specs

Freescale Semiconductor, Inc...

Freescale Semiconductor, Inc.

To use an external clock source (see Figure 4-6), the operating clock frequency can be driven directly into the EXTAL pin (the XTAL pin must be left floating for this case). This approach results in a system clock and CLKOUT that are the same as the input signal frequency, but not tightly coupled to it. To enable this mode, MODCK must be held low during reset, and VCCSYN held at 0 V while the chip is in operation.

VCCSYN

XFC1

0.1 µF

EXTERNAL

CLOCK

EXTAL		XTAL	XFC PIN	VCCSYN	.01 µF
	CRYSTAL	PHASE	LOW-PASS
	OSCILLATOR	PHASE	LOW-PASS		VCO
	OSCILLATOR	COMPARATOR	FILTER		VCO
		COMPARATOR	FILTER
2			FEEDBACK
2			DIVIDER
			DIVIDER
			CLOCK CONTROL		CLKOUT
					SYSTEM
					CLOCK

NOTES:

1.Must be low-leakage capacitor.

2.External mode uses this path only.

Figure 4-6. Clock Block Diagram for External Oscillator Operation

Alternatively, an external clock signal can be directly driven into EXTAL (with XTAL left floating) using the on-chip PLL. This configuration results in an internal clock and CLKOUT signal of the same frequency as the input signal, with a tight skew between the external clock and the internal clock and CLKOUT signals. To enable this mode, MODCK must be held low during reset, and VCCSYN should be connected to a quiet 5-V source.

If an input signal loss for either of the clock modes utilizing the PLL occurs, chip operation can continue in limp mode with the VCO running at approximately one-half the operating speed (affected by the value of the X-bit in the SYNCR), using an internal voltage reference. The SLIMP bit in the SYNCR indicates that a loss of input signal reference has been detected. The RSTEN bit in the SYNCR controls whether an input signal loss causes a system reset or causes the device to operate in limp mode. The SLOCK bit in the SYNCR indicates when the VCO has locked onto the desired frequency or if an external clock is being used.

4.2.3.1PHASE COMPARATOR AND FILTER. The phase comparator takes the output of the frequency divider and compares it to an external input signal reference. The result of

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MC68340 USER’S MANUAL

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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.

Motorola MC68340 manual Clock Block Diagram for External Oscillator Operation

Models: MC68340

Freescale Semiconductor, Inc...

Freescale Semiconductor, Inc.

Figure 4-6. Clock Block Diagram for External Oscillator Operation

MC68340 specifications