Zilog Z16C35 Manuel d'utilisateur télécharger pdf (Page 201)

Application Note

The Z180™ Interfaced with the SCC at MHZ

(Continued)

;external/status interrupt

service routine

ext_stat: ld a,10h

out (scc_cont),a ;reset ext/stat int

in a,(scc_cont) ;read stat

and 00100000b ;mask off bits other than /cts

rra ;shift into D0 loc

rra

set 1,a ;set interrupt ﬂag

ld b,a ;save it

ld a,38h

out (scc_cont),a ;reset highest ius

ei ;enable int

ret ;return from int

;initialization data table for scc

;table format - register number, then value for the register

;and ends with 0ffh - since scc doesn’t have

;register 0ffh...

scctab: db 09h ;select WR9

if scc_a

db 10000000b ;ch a reset

else

db 01000000b ;ch b reset

endif

db 0eh ;select WR15

db 20h ;only enable /cts int

db 01h ;select WR1

db 00000001b ;enable ext/stat int

db 10h ;reset ext/stat int

db 10h ;twice

db 09h ;select WR9

db 08h ;mie, vect not incl. stat

db 0ffh ;end of table

;interrupt vector table

org inttest + 100h

sccvect: dw ext_stat

.block 100h ;reserve area for stack

top_of_sp:

end

Table 12. SCC Test Program – Interrupt for 180/SCC Application Board (Under Mode2 Interrupt) (Continued)

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Zilog Z16C35 Manuel d'utilisateur Page 201

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