Скачиваний:
38
Добавлен:
27.04.2015
Размер:
3.97 Mб
Скачать

Freescale Semiconductor, Inc.

ARCHIVED BY FREESCALE SEMICONDUCTOR, INC. 2005

Freescale Semiconductor, Inc.DSP56824 Memory Map

ARCHIVED BY FREESCALE SEMICONDUCTOR, INC. 2005

NOTE:

When the EX bit is set, only the upper 64 peripheral memory-mapped locations are accessible (X:$FFC0–$FFFF) with the I/O short addressing mode. The lower 64 memory-mapped locations (X:$FF80–$FFBF) are not accessible when the EX bit is set. An access to these addresses results in an access to external memory.

The EX bit is cleared by processor reset.

3.1.2.9 Reserved Bit—Bit 2

The OMR bit 2 is reserved. It is read as zero during DSP read operations and should be written with zero to ensure future compatibility.

3.1.2.10 Operating Mode (MB, MA)—Bits 1–0

The chip operating mode (MB and MA) bits indicate the operating mode and memory maps of the DSP56824. These bits are loaded from the external mode select pins MODB and MODA on processor reset. After the DSP leaves the Reset state, MB and MA may be changed under program control. Operating modes for the DSP56824 are shown in Table 3-5 on page 3-12.

3.1.3 DSP56824 Status Register (SR)

The status register (SR) is a 16-bit register consisting of an 8-bit mode register (MR) and an 8-bit condition code register (CCR). The MR is the high-order 8 bits of the SR; the CCR is the low-order 8 bits. A full description of the SR is provided in the DSP56800 Family Manual. The programming model for the SR is shown in Figure 3-4.

 

 

 

 

 

MR

 

 

 

 

 

 

CCR

 

 

 

SR

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Status Register

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reset = $0300

LF

*

*

*

*

*

I1

I0

SZ

L

E

U

N

Z

V

C

Read/Write

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LF— Loop Flag

I[1:0]— Interrupt Mask

SZ— Size

L— Limit

E— Extension

U— Unnormalized

N— Negative

Z— Zero

V— Overflow

C— Carry

* Indicates reserved bits, read as zero and should be written with zero for future compatibility

AA1433

Figure 3-4. Status Register Programming Model

Within the SR, the MR is of special concern to DSP56824 users, as it allows masking or enabling interrupts for the on-chip peripherals. On reset, the SR is set to $0300, which enables interrupts having IPL 1 (listed in Table 3-7 on page 3-16) but masks interrupts with level IPL 0. All the on-chip peripheral

Memory Configuration and Operating Modes

3-7

For More Information On This Product,

Go to: www.freescale.com

Соседние файлы в папке DSP568xx