DSP56303 datasheet(226/292 Pages) FREESCALE

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DSP56303 User’s Manual, Rev. 2

A-4

Freescale Semiconductor

Bootstrap Program

START

clr a #$0a,X0; clear a and load X0 with constant 0a0000

jclr #2,omr,EPRSCILD ; If MC:MB:MA=0xx, go load from EPROM/SCI

jclr #1,omr,OMR1IS0; IF MC:MB:MA=10x, go to look for ISA/HC11 options

jclr #0,omr,I8051HOSTLD; If MC:MB:MA=110, go load from 8051 Host

jmp

MC68302HOSTLD; If MC:MB:MA=111, go load from MC68302 Host

OMR1IS0

jset #0,omr,HC11HOSTLD; If MC:MB:MA=101, go load from HC11 Host

; If MC:MB:MA=100, go load from ISA HOST

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

; This is the routine which loads a program through the HI08 host port

; The program is downloaded from the host MCU with the following scenario:

; 1) 3 bytes - Define the program length.

; 2) 3 bytes - Define the address to which to start loading the program to.

; 3) 3n bytes (while n is any integer number)

; The program words will be 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.

; The host MCU may terminate the loading process by setting the HF1=0 and HF0=1.

; When the downloading is terminated, the program will start execution of the

; loaded program from the specified starting address.

; The HI08 boot ROM program enables the following busses to download programs

; through the HI08 port:

;

1 - ISA- Dual strobes non-multiplexed bus with negative strobe

;

pulses dual positive request

;

2 - HC11- Single strobe non-multiplexed bus with positive strobe

;

pulse single negative request.

;

4 - i8051

- Dual strobes multiplexed bus with negative strobe pulses

;

dual negative request.

;

5 - MC68302 - Single strobe non-multiplexed bus with negative strobe

;

pulse single negative request.

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

ISAHOSTLD

movep #%0101000000011000,x:M_HPCR

; Configure the following conditions:

; HAP

= 0 Negative host acknowledge

; HRP

= 1 Positive host request

; HCSP

= 0 Negative chip select input

; HD/HS

= 1 Dual strobes bus (RD and WR strobes)

; HMUX

= 0 Non multiplexed bus

; HASP

= 0 (address strobe polarity has no

;

meaning in non-multiplexed bus)

; HDSP

= 0 Negative data strobes polarity

; HROD

= 0 Host request is active when enabled

;

spare = 0 This bit should be set to 0 for

;

future compatibility

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