Freescale Semiconductor, Inc...

Freescale Semiconductor, Inc.

5.2.2 Registers

Registers D7–D0 are used as data registers for bit, byte (8-bit), word (16-bit), long-word (32-bit), and quad-word (64-bit) operations. Registers A6 to A0 and the USP and SSP are address registers that may be used as software SPs or base address registers. Register A7 (shown as A7 and A7' in Figures 5-3 and 5-4) is a register designation that applies to the USP in the user privilege level and to the SSP in the supervisor privilege level. In addition, address registers may be used for word and long-word operations. All of the 16 general-purpose registers (D7–D0, A7–A0) may be used as index registers.

The PC contains the address of the next instruction to be executed by the CPU32. During instruction execution and exception processing, the processor automatically increments the contents of the PC or places a new value in the PC, as appropriate.

The SR (see Figure 5-5) contains condition codes, an interrupt priority mask (three bits), and three control bits. Condition codes reflect the results of a previous operation. The codes are contained in the low byte (CCR) of the SR. The interrupt priority mask determines the level of priority an interrupt must have to be acknowledged. The control bits determine trace mode and privilege level. At user privilege level, only the CCR is available. At supervisor privilege level, software can access the full SR.

The VBR contains the base address of the exception vector table in memory. The displacement of an exception vector is added to the value in this register to access the vector table.

Alternate source and destination function code registers (SFC and DFC) contain 3-bit function codes. The CPU32 generates a function code each time it accesses an address. Specific codes are assigned to each type of access. The codes can be used to select eight dedicated 4-Gbyte address spaces. The MOVEC instruction can use registers SFC and DFC to specify the function code of a memory address.

 

 

 

 

 

 

SYSTEM BYTE

 

 

 

 

 

 

 

 

 

 

 

 

USER BYTE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(CONDITION CODE REGISTER)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15

 

14

13

12

11

10

9

 

8

 

 

7

6

5

4

 

3

 

2

1

0

 

 

 

 

 

 

 

 

 

 

 

T1

T0

S

0

0

I2

 

I1

 

I0

0

0

0

X

 

N

 

Z

 

V

C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TRACE

 

 

 

 

 

INTERRUPT

 

 

 

 

 

 

EXTEND

 

 

 

 

 

 

 

 

 

 

 

 

ENABLE

 

 

 

 

PRIORITY MASK

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NEGATIVE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SUPERVISOR/USER

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ZERO

 

 

 

 

 

 

 

 

 

STATE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OVERFLOW

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CARRY

Figure 5-5. Status Register

5- 10MC68340 USER’S MANUALMOTOROLA

For More Information On This Product,

Go to: www.freescale.com

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Image 147
Motorola MC68340 manual Freescale Semiconductor, Inc Registers, Status Register
Page 146 Page 148

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.
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