Fault Recovery | Motorola MC68340 guide

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attempting to read the stack frame. The version number is located in the most significant byte (bits 15–8) of the internal register word at location SP + $14 in the stack frame. The validity check ensures that stack frame data will be properly interpreted in multiprocessor systems.

If a frame is invalid, a format error exception is taken. If it is inaccessible, a bus error exception is taken. Otherwise, the processor reads the entire frame into the proper internal registers, de-allocates the stack (12 words), and resumes normal processing. Bus error frames for faults during exception processing require the RTE instruction to rewrite the faulted stack frame. If an error occurs during any of the bus cycles required by rewrite, the processor halts.

If a format error occurs during RTE execution, the processor creates a normal four-word fault stack frame below the frame that it was attempting to use. If a bus error occurs, a bus-error stack frame will be created. The faulty stack frame remains intact, so that it may be examined and repaired by an exception handler or used by a different type of processor (e.g., MC68010, MC68020, or future M68000 processor) in a multiprocessor system.

5.5.3 Fault Recovery

There are four phases of recovery from a fault: recognizing the fault, saving the processor state, repairing the fault (if possible), and restoring the processor state. Saving and restoring the processor state are described in the following paragraphs.

The stack contents are identified by the special status word (SSW). In addition to identifying the fault type represented by the stack frame, the SSW contains the internal processor state corresponding to the fault.

15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
TP	MV	0	TR	B1	B0	RR	RM	IN	RW	LG	SIZ			FUNC

TP—BERR frame type

MV—MOVEM in progress

TR—Trace pending

B1—Breakpoint channel 1 pending

B0—Breakpoint channel 0 pending

RR—Rerun write cycle after RTE

RM—Faulted cycle was read-modify-write

IN—Instruction/other

RW—Read/write of faulted bus cycle

LG—Original operand size was long word

SIZ—Remaining size of faulted bus cycle

FUNC—Function code of faulted bus cycle

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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 Fault Recovery

Models: MC68340

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

5.5.3 Fault Recovery

MC68340 specifications