Motorola 009 Instrukcja Użytkownika Pobierz pdf (Strona 19)

System Overview

DSP Subsystem Code

MOTOROLA

SHI Port Usage

2-7

Example 2-1

SHI Boot in SPI Mode Section of Bootstrap ROM Program

; This is the routine that loads from the Serial Host Interface.

; MC:MB:MA=101 - Bootstrap from SHI (SPI)

; MC:MB:MA=111 - Bootstrap from SHI (IIC)

; If MC:MB:MA=1x1, the internal program RAM is loaded with 512 words received

; through the Serial Host Interface (SHI). 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 IIC mode, according to the bootstrap

; mode. The OnCE is enabled by the bootstrap code.

shild jclr #ma,omr,ma_0

shild_1 movep a,x:ogdbr ; enable the OnCE

move #$0002A9,x1 ; SHI control word (SPI)

; HEN=1, HI2C=0, HM1-HM0=10, HFIFO=1, HMST=0,

; HRQE1-HRQE0=01, HIDLE=1, HBIE=0, HTIE=0, HRIE1-HRIE0=00

move #<0,r0 ; start loading code at P:$0

jmp <$100

org pl:$100,pl:$100 ; Start of second 32-word group

jclr #mb,omr,shi_loop ; If MC:MB:MA=101, then SPI

bset #hi2c,x1 ; IIC (HI2C=1)

shi_loop movep x1,x:hcsr ; enable SHI

do #512,_loop2

jclr #hrne,x:hcsr,* ; wait for HRX not empty

movep x:hrx,p:(r0)+ ; store in Program RAM

_loop2

jmp <exit ; Finish

ma_0 jmp <shild_1 ; make MC:MB:MA=1x0 equal to MC:MB:MA=1x1

; This code fills the unused bootstrap rom locations with their address

dup $120-*

dc *

endm

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Motorola 009 Instrukcja Użytkownika Strona 19