Freescale Semiconductor DSP56366 - Manual (Page 258)

DSP56366 Bootstrap Program
DSP56366 24-Bit Digital Signal Processor User Manual, Rev. 4
A-6 Freescale Semiconductor
; MD:MC:MB:MA=0001
EPROMLD
move #BOOT,r2 ; r2 = address of external EPROM
movep #AARV,X:M_AAR1 ; aar1 configured for SRAM types of access
do #6,_LOOP9 ; read number of words and starting address
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.
nop ; pipeline delay
_LOOP10 ; and go get another 24-bit word.
; Boot from EPROM done
bra
OMR1XXX
jclr #MC,omr,BURN_RESER ; IF MD:MC:MB:MA=101x, go to RESERVED
; IF MD:MC:MB:MA=1001, go to BURN
jclr #MB,omr,OMR1IS0 ; IF MD:MC:MB:MA=110x, go to look for ISA/HC11
jclr #MA,omr,I8051HOSTLD ; If MD:MC:MB:MA=1110, go load from 8051 Host
; If MD:MC:MB:MA=1111, go load from MC68302 Host
;========================================================================
; This is the routine which loads a program through the HDI08 host port
; The program is downloaded from the host MCU with the following rules:
; 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 the program length defined by the 3 first bytes)
; 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 HDI08 boot ROM program enables the following busses to download programs
; through the HDI08 port:
;
; C - ISA - Dual strobes non-multiplexed bus with negative strobe
; pulses dual positive request
; D - HC11 - Single strobe non-multiplexed bus with positive strobe
; pulse single negative request.