DSP56303 datasheet(230/292 Pages) FREESCALE

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DSP56303 User’s Manual, Rev. 2

A-8

Freescale Semiconductor

Bootstrap Program

movem p:(r2)+,a2

; Get the 8 LSB from ext. P mem.

asr #8,a,a

; Shift 8 bit data into A1

_LOOP9

;

move a1,r0

; starting address for load

move a1,r1

; save it in r1

; a0 holds the number of words

do a0,_LOOP10

; read program words

do #3,_LOOP11

; Each instruction has 3 bytes

movem p:(r2)+,a2

; Get the 8 LSB from ext. P mem.

asr #8,a,a

; Shift 8 bit data into A1

_LOOP11

; Go get another byte.

movem a1,p:(r0)+

; Store 24-bit result in P mem.

_LOOP10

; and go get another 24-bit word.

; Boot from EPROM done

;========================================================================

FINISH

; This is the exit handler that returns execution to normal

; expanded mode and jumps to the RESET vector.

andi #$0,ccr

; Clear CCR as if RESET to 0.

jmp (r1)

; Then go to starting Prog addr.

; End of bootstrap code. Number of program words: 91

;*****************************************************************************

;

EQUATES for 56303 I/O registers and ports

;

Last update: June 11 1995

;

;*****************************************************************************

page132,55,0,0,0

optmex

ioequ

ident

1,0

A.2 Equates for I/O Port Programming

;------------------------------------------------------------------------

;

M_HDR

EQU

$FFFFC9

; Host port GPIO data Register

M_HDDR

EQU

$FFFFC8

; Host port GPIO direction Register

M_PCRC

EQU

$FFFFBF

; Port C Control Register

M_PRRC

EQU

$FFFFBE

; Port C Direction Register

M_PDRC

EQU

$FFFFBD

; Port C GPIO Data Register

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