Format $0-Four-Word Stack Frame | Motorola MC68340 specification

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5.5.4 CPU32 Stack Frames

The CPU32 generates three different stack frames: four-word frames, six-word frames, and twelve-word bus error frames.

5.5.4.1FOUR-WORD STACK FRAME. This stack frame is created by interrupt, format error, TRAP #n, illegal instruction, A-line and F-line emulator trap, and privilege violation exceptions. Depending on the exception type, the PC value is either the address of the next instruction to be executed or the address of the instruction that caused the exception (see Figure 5-12).

	15				0
SP ⇒					STATUS REGISTER
+$02					PROGRAM COUNTER HIGH
					PROGRAM COUNTER LOW
+$06	0	0	0	0	VECTOR OFFSET

Figure 5-12. Format $0—Four-Word Stack Frame

5.5.4.2SIX-WORD STACK FRAME. This stack frame (see Figure 5-13) is created by instruction-related traps, which include CHK, CHK2, TRAPcc, TRAPV, and divide-by-zero, and by trace exceptions. The faulted instruction PC value is the address of the instruction that caused the exception. The next PC value (the address to which RTE returns) is the address of the next instruction to be executed.

	15				0
SP ⇒					STATUS REGISTER
+$02				NEXT INSTRUCTION PROGRAM COUNTER HIGH
					NEXT INSTRUCTION PROGRAM COUNTER LOW
+$06	0	0	1	0	VECTOR OFFSET
+$08				FAULTED INSTRUCTION PROGRAM COUNTER HIGH
				FAULTED INSTRUCTION PROGRAM COUNTER LOW

Figure 5-13. Format $2—Six-Word Stack Frame

Hardware breakpoints also utilize this format. The faulted instruction PC value is the address of the instruction executing when the breakpoint was sensed. Usually this is the address of the instruction that caused the breakpoint, but, because released writes can overlap following instructions, the faulted instruction PC may point to an instruction following the instruction that caused the breakpoint. The address to which RTE returns is the address of the next instruction to be executed.

5.5.4.3BUS ERROR STACK FRAME. This stack frame is created when a bus cycle fault is detected. The CPU32 bus error stack frame differs significantly from the equivalent stack frames of other M68000 Family members. The only internal machine state required in the CPU32 stack frame is the bus controller state at the time of the error and a single register.

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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 Freescale Semiconductor, Inc 4 CPU32 Stack Frames

Models: MC68340

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

5.5.4 CPU32 Stack Frames

Figure 5-12. Format $0—Four-Word Stack Frame

Figure 5-13. Format $2—Six-Word Stack Frame

MC68340 specifications