Z85233 Datasheet, PDF (276/317 Pages) Zilog, Inc. – The Zilog SCC Serial Communication Controller

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00000282 0e08
00000284 cdWwww
00000287682 l6:
00000287 3aWwww
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0000028c 28f9
0000028e cb8f
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00000295 d3e5
00000297 0602
00000299 21Wwww
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000002b5 28f6
000002b7717 txq1:
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UM010901-0601
Application Note
Technical Considerations When Implementing LocalTalk Link Access Protocol
660
out
(scc_cont),a
661
ld
a,01101011b ;sdlc crc,
662
663
;txcrc enable,
;reset rts
1
664
out
(scc_cont),a
665
666
;
667
;**start counting out 2 flag character times **
668
;
669
;count 16 bit times
670
;from the rs-422 enable
671
;for 2 flags.
672
;btdelay=subr delay+ctc1int+polling=8bits
673
;16 bit times-btdelay=16-8=08h
674
;
675
ld
c,08h
676
call
bittime
;bittime delay
677
;is stored in reg.c
678
;and bit1 of timflg
679
;will indicate
680
;count termination.
681
;timer flag
683
ld
a,(timflg)
;
684
bit
1,a
;if bit1=1 then
685
;count terminated
686
jr
z,l6
;
687
res
1,a
;reset timflg bit1
688
ld
(timflg),a
;update timflg
689
;
690
ld
a,03h
;
691
out
(ctc1_cont),a ;disable int,
692
;software reset
693
;to kill the counter1
694
ld
b,02h
;2+1 bytes to transmitted
695
ld
hl,txlapenq
;point to txlapenq buffer
696
;send 1st byte
697
ld
a,(hl)
;
698
out
(scc_data),a ;and send it
699
inc
hl
;point to the next byte
700
;
701
ld
a,0c0h
;reset eom latch command
702
out
(scc_cont),a
703
;
704
di
;disable all int
705
ld
a,0ah
;select WR10
706
out
(scc_cont),a
707
;idle with 1’s
708
;at the end of the frame
709
ld
a,11101000b
710
out
(scc_cont),a
711
;
712 txq2: ld
a,00h
713
out
(scc_cont),a ;rr0
714
in
a,(scc_cont) ;read rr0
715
bit
2,a
;read tx buffer empty
716
jr
z,txq2
;loop if zero
718
ld
719
out
720
inc
721
a,(hl)
(scc_data),a
hl
;
;and send it
;point to the next byte
6-141