Freescale Semiconductor DSP56374 User Manual page 172

DSP56374 Bootstrap Program
ORG PH:STRAP_START
BootStrap:
START
movep #$0,X:M_OGDB
nop
nop
nop
nop
nop
clr a #$0,r5
move omr,a
and #>$f,a
move #-1,m0
add #ModeJIT,a
move a,r0
move p:(r0),r1
jmp r1
;========================================================================
; This is the routine that jumps to the internal Program ROM.
; MD:MC:MB:MA=0010
mode2
move #>1,a
move a,y:OMRSave
bootSA:
move #PROMADDR,r1
bra <FINISH
;========================================================================
; This is the routine that loads from SHI.
; MD:MC:MB:MA=0100 - reserved for SHI
; MD:MC:MB:MA=0101 - Bootstrap from SHI (SPI slave)
; MD:MC:MB:MA=0110 - Bootstrap from SHI (I2C slave,with spike filter HCKFR=0)
; MD:MC:MB:MA=0111 - Bootstrap from SHI (I2C slave, HCKFR=0)
; This is the routine which loads a program through the SHI port.
; The SHI operates in the slave
; mode, with the 10-word FIFO enabled, and with the HREQ pin enabled for
; receive operation. The word size for transfer is 24 bits. The SHI
; operates in the SPI or in the I2C mode, according to the bootstrap mode.
;
; The program is downloaded according to 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 first 3 bytes)
; The program words will be stored in contiguous PRAM memory locations starting
; at the specified starting address.
; After storing the program words, program execution starts from the same
; address where loading started.
mode5:
mode6:
mode7:
A-2
; bootstrap code starts at $ff0000
; enable OnCE
; 5 NOP instructions, needed for test procedure
; clear a and init R5 with 0
; store starting PROM address in r1
DSP56374 Users Guide, Rev. 1.2
Freescale Semiconductor