DSP56303 datasheet(223/292 Pages) FREESCALE

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DSP56303 User’s Manual, Rev. 2

Freescale Semiconductor

A-1

Bootstrap Program

This appendix lists the bootstrap program and equates for the DSP56303. Freescale posts updates

to the bootstrap program on the Worldwide Web at the web site listed on the back cover of this

manual.

A.1 Bootstrap Code

; Revised June, 29 1995.

;

; Bootstrap through the Host Interface, External EPROM or SCI.

;

; This is the Bootstrap program contained in the DSP56303 192-word Boot

; ROM. This program can load any program RAM segment from an external

; EPROM, from the Host Interface or from the SCI serial interface.

;

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

; If MD:MC:MB:MA=1000, then the Boot ROM is bypassed and the DSP56303 will

; start fetching instructions beginning with the address $8000 assuming that

; an external memory of SRAM type is used. The accesses will be performed

; using 31 wait states with no address attributes selected (default area).

;

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

; If MC:MB:MA=001, then it loads a program RAM segment from consecutive

; byte-wide P memory locations, starting at P:$D00000 (bits 7-0).

; The memory is selected by the Address Attribute AA1 and is accessed with

; 31 wait states.

; The EPROM bootstrap code expects to read 3 bytes

; specifying the number of program words, 3 bytes specifying the address

; to start loading the program words and then 3 bytes for each program

; word to be loaded. The number of words, the starting address and the

; program words are read least significant byte first followed by the

; mid and then by the most significant byte.

; The program words will be condensed into 24-bit words and stored in

; contiguous PRAM memory locations starting at the specified starting

: address.

; After reading the program words, program execution starts from the same

; address where loading started.

;

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

; If MC:MB:MA=010, then it loads the program RAM from the SCI interface.

; The number of program words to be loaded and the starting address must

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