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Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

DSP56002 OPERATING MODES

Chip operating modes can also be changed using software to write the operating mode bits (MC, MB, MA) in the OMR. Changing operating modes does not reset the DSP.

Note: The user should disable interrupts immediately before changing the OMR to prevent an interrupt from going to the wrong memory location. Also, one no-operation (NOP) instruction should be included after changing the OMR to allow for remapping to occur.

Table 3-2 DSP56002 Operating Mode Summary

Operating

M

M

M

Description

Mode

C

B

A

 

 

 

 

 

 

 

 

 

 

 

0

0

0

0

Single-Chip Mode - P: RAM enabled, reset @ $0000

 

 

 

 

 

1

0

0

1

Bootstrap from EPROM, exit in Mode 0

 

 

 

 

 

2

0

1

0

Normal Expanded Mode - P: RAM enabled, reset @ $E000

 

 

 

 

 

3

0

1

1

Development Mode - P: RAM disabled, reset @ $0000

 

 

 

 

 

4

1

0

0

Reserved for Bootstrap

 

 

 

 

 

5

1

0

1

Bootstrap from Host, exit in Mode 0

 

 

 

 

 

6

1

1

0

Bootstrap from SCI (external clock), exit in Mode 0

 

 

 

 

 

7

1

1

1

Reserved for Bootstrap

 

 

 

 

 

3.4.1Single Chip Mode (Mode 0)

In the single-chip mode, all internal program and data RAM memories are enabled (see Figure 3-1). A hardware reset causes the DSP to jump to internal program memory location $0000 and resume execution. The memory maps for mode 0 and mode 2 (see Figure 3-1) are identical. The difference between the two modes is that reset vectors to program memory location $0000 in mode 0 and vectors to location $E000 in mode 2.

3.4.2Bootstrap From EPROM (Mode 1)

The bootstrap modes allow the DSP to load a program from an inexpensive byte-wide ROM into internal program memory during a power-on reset. On power-up, the waitstate generator adds 15 wait states to all external memory accesses so that slow memory can be used. The bootstrap program uses the bytes in three consecutive memory locations in the external ROM to build a single word in internal program memory.

3 - 8 MEMORY MODULES AND OPERATING MODES MOTOROLA

For More Information On This Product, Go to: www.freescale.com

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

DSP56002 OPERATING MODES

In the bootstrap mode, the chip enables the bootstrap ROM and executes the bootstrap program. (The bootstrap program code is shown in Appendix A.) The bootstrap ROM contains the bootstrap firmware program that performs initial loading of the DSP56002 program RAM. Written in DSP56002 assembly language, the program initializes the program RAM by loading from an external byte-wide EPROM starting at location P:$C000.

The EPROM is typically connected to the chip’s address and data bus.The data contents of the EPROM must be organized as shown in Table 3-3 Organization of EPROM Data Contents.

+5 V

FROM OPEN

COLLECTOR

BUFFER

MBD301*

MBD301*

FROM

RESET

FUNCTION

MBD301*

FROM OPEN

COLLECTOR

BUFFER

DR

DSP56002

 

 

BR

 

 

 

HACK

 

 

WT

 

 

 

MODA/IRQA

 

 

MODC/NMI

 

2716

 

 

 

PS

 

CE

 

A0-A10

11

A0-A10

 

 

RESET

8

D0-D7

 

D0-D7

 

MODB/IRQB

 

 

 

 

Notes: 1. *These diodes must be Schottky diodes.

 

 

2. All resistors are 15KΩ unless noted otherwise.

 

 

3. When in RESET,

IRQA,

 

IRQB

and

NMI

must

 

 

be deasserted by external peripherals.

 

 

 

 

 

 

 

 

 

 

ADDRESS OF EXTERNAL

CONTENTS LOADED

BYTE-WIDE P MEMORY

 

TO INTERNAL P: RAM AT:

 

 

 

 

 

 

 

P:$C000

 

P:$0000 LOW BYTE

 

 

 

 

 

 

 

P:$C001

 

P:$0000 MID BYTE

 

 

 

 

 

 

 

P:$C002

 

P:$0000 HIGH BYTE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

P:$C5FD

 

P:$01FF LOW BYTE

 

 

 

 

 

 

 

P:$C5FE

 

P:$01FF MID BYTE

 

 

 

 

 

 

 

P:$C5FF

 

P:$01FF HIGH BYTE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 3-3 Port A Bootstrap Circuit

MOTOROLA MEMORY MODULES AND OPERATING MODES 3 - 9

For More Information On This Product, Go to: www.freescale.com

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