Function Codes FC3-FC0, Chip Selects CS3-CS0

Freescale Semiconductor, Inc...

Freescale Semiconductor, Inc.

last falling edge of the clock for that bus cycle. For a write cycle, all 16 bits of the data bus are driven, regardless of the port width or operand size. The MC68340 places the data on the data bus approximately one-half clock cycle after AS is asserted in a write cycle.

2.4 FUNCTION CODES (FC3–FC0)

These signals are outputs that indicate one of 16 address spaces to which the address applies. Fifteen of these spaces are designated as either user or supervisor, program or data, and normal or direct memory access (DMA) spaces. One other address space is designated as CPU space to allow the CPU32 to acquire specific control information not normally associated with read or write bus cycles. The function code signals are valid while AS is asserted. See Table 2-2 for more information.

Table 2-2. Address Space Encoding

	Function Code Bits
3	2	1	0	Address Spaces
0	0	0	0	Reserved (Motorola)
0	0	0	1	User Data Space
0	0	1	0	User Program Space
0	0	1	1	Reserved (User )
0	1	0	0	Reserved (Motorola)
0	1	0	1	Supervisor Data Space
0	1	1	0	Supervisor Program Space
0	1	1	1	CPU Space
1	x	x	x	DMA Space

2.5 CHIP SELECTS (CS3–CS0)

These pins can be programmed to be chip select output signals, port B parallel I/O and autovector input, or additional interrupt request lines. Refer to Section 4 System Integration Module for more information on these signals.

CS3– CS0

The chip select output signals enable peripherals at programmed addresses. These signals are inactive high (not high impedance) after reset. CS0 is the chip select for a boot ROM containing the reset vector and initialization program. It functions as the boot chip select immediately after reset.

IRQ4, IRQ2, IRQ1

Interrupt request lines are external interrupt lines to the CPU32. These additional interrupt request lines are selected by the FIRQ bit in the module configuration register.

MOTOROLAMC68340 USER’S MANUAL2- 5

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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 Function Codes FC3-FC0, Chip Selects CS3-CS0, Address Space Encoding

Models: MC68340