Central Processor Unit (CPU) Registers

Table 4-3.Status Register Bit Definitions (Continued)

Bit Number

Bit Name

Reset Value

Description

 

 

 

 

 

 

 

 

20

SM

0

Arithmetic Saturation Mode

 

 

 

Selects automatic saturation on 48 bits for the results going to the

 

 

 

accumulator. This saturation is performed by a special circuit inside the

 

 

 

MAC unit. The purpose of this bit is to provide an Arithmetic Saturation

 

 

 

mode for algorithms that do not recognize or cannot take advantage of the

 

 

 

extension accumulator.

 

 

 

 

19

CE

0

Cache Enable

 

 

 

Enables/disables the instruction cache controller. If CE is set, the cache is

 

 

 

enabled, and instructions are cached into and fetched from the internal

 

 

 

Program RAM. If CE is cleared, the cache is disabled and the DSP56300

 

 

 

core fetches instructions from external or internal program memory,

 

 

 

according to the memory space table of the specific DSP56300 core-based

 

 

 

device.

 

 

 

Note: To ensure proper operation, do not clear Cache Enable mode

 

 

 

while Burst mode is enabled (OMR[BE] is set).

 

 

 

 

18

 

0

Reserved. Write to zero for future compatibility.

17

SA

0

Sixteen-Bit Arithmetic Mode

 

 

 

Affects data width functionality, enabling the Sixteen-bit Arithmetic mode of

 

 

 

operation. When SA is set, the core uses 16-bit operations instead of 24-bit

 

 

 

operations. In this mode, 16-bit data is right-aligned in the 24-bit memory

 

 

 

locations, registers, and 24-bit register portions. Shifting, limiting, rounding,

 

 

 

arithmetic instructions, and moves are performed accordingly. For details

 

 

 

on Sixteen-Bit Arithmetic mode, consult the DSP56300 Family Manual.

 

 

 

 

16

FV

0

DO FOREVER Flag

 

 

 

Set when a DO FOREVER loop executes. The FV flag, like the LF flag, is

 

 

 

restored from the stack when a DO FOREVER loop terminates. Stacking

 

 

 

and restoring the FV flag when initiating and exiting a DO FOREVER loop,

 

 

 

respectively, allow program loops to be nested. When returning from the

 

 

 

long interrupt with an RTI instruction, the system stack is pulled and the

 

 

 

value of the FV bit is restored.

 

 

 

 

15

LF

0

Do Loop Flag

 

 

 

When a program loop is in progress, enables the detection of the end of the

 

 

 

loop. The LF is restored from stack when a program loop terminates.

 

 

 

Stacking and restoring the LF when initiating and exiting a program loop,

 

 

 

respectively, allow program loops to be nested. When returning from the

 

 

 

long interrupt with an RTI instruction, the System Stack is pulled and the LF

 

 

 

bit value is restored.

 

 

 

 

4-8

DSP56301 User’s Manual

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Motorola DSP56301 user manual Cache Enable, Sixteen-Bit Arithmetic Mode, Do Forever Flag, Do Loop Flag
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DSP56301 specifications

The Motorola DSP56301 is a highly efficient digital signal processor, specifically engineered for real-time audio and speech processing applications. This DSP is part of Motorola's renowned DSP56300 family, which is recognized for its innovative features and outstanding performance in the realm of digital signal processing.

One of the main features of the DSP56301 is its ability to handle complex computations at high speeds. With a maximum clock frequency of 66 MHz, it delivers fast performance, enabling it to process audio signals in real time. The chip is built on a 24-bit architecture, which allows for high-resolution audio processing. This is particularly beneficial in applications such as telecommunications, consumer audio devices, and professional audio equipment, where precision is paramount.

The DSP56301 boasts a comprehensive instruction set that includes efficient mathematical operations, which are essential for digital filters and audio effects processing. One of the key innovations of this device is its dual data path architecture, which permits simultaneous processing of multiple data streams. This feature significantly enhances the device's throughput and responsiveness, making it suitable for demanding applications such as voice recognition and synthesis.

In terms of memory regions, the DSP56301 includes several on-chip memory categories, such as program memory, data memory, and a specialized memory for coefficients. The architecture's support for external memory expansion further increases its versatility, allowing designers to tailor systems to their specific requirements.

The DSP56301 implements advanced features such as a powerful on-chip hardware multiplier and accumulator, simplifying complex mathematical tasks and accelerating the execution of algorithms. Its flexible interrupt system enhances its capability to respond to time-sensitive operations, while the integrated serial ports facilitate efficient data communication with external devices.

Power consumption is also a vital characteristic of the DSP56301. It is designed with energy efficiency in mind, allowing for extended operation in battery-powered devices. The chip’s low power requirements are particularly advantageous in portable audio devices and other applications where energy conservation is crucial.

In conclusion, the Motorola DSP56301 is an exceptional digital signal processor that combines high processing power, flexibility, and efficiency. Its main features, advanced technologies, and robust architecture make it a top choice for developers seeking to create sophisticated audio and signal processing systems. With its enduring legacy in the industry, the DSP56301 continues to be relevant in a variety of modern applications, ensuring it remains a valuable tool for engineers and designers.
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