Zilog Z16C35 User Manual
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
rra
rra
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)
Page 195 of 316
UM011002-0808