Zilog Z16C35 User Manual
Page 291
14-11
1
0000027c d3e8
660
out
(scc_cont),a
0000027e 3e6b
661
ld
a,01101011b
;sdlc crc,
662 ;txcrc
enable,
663 ;reset
rts
00000280 d3e8
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 ;
00000282 0e08
675
ld
c,08h
00000284 cdWwww
676
call
bittime
;bittime delay
677
;is stored in reg.c
678
;and bit1 of timflg
679 ;will
indicate
680 ;count
termination.
681
00000287682 l6:
;timer flag
00000287 3aWwww
683
ld
a,(timflg)
;
0000028a cb4f
684
bit
1,a
;if bit1=1 then
685 ;count
terminated
0000028c 28f9
686
jr
z,l6
;
0000028e cb8f
687
res
1,a
;reset timflg bit1
00000290 32Wwww
688
ld
(timflg),a
;update timflg
689
;
00000293 3e03
690
ld
a,03h
;
00000295 d3e5
691
out
(ctc1_cont),a
;disable int,
692 ;software
reset
693
;to kill the counter1
00000297 0602
694
ld
b,02h
;2+1 bytes to transmitted
00000299 21Wwww
695
ld
hl,txlapenq
;point to txlapenq buffer
696
;send 1st byte
0000029c 7e
697
ld
a,(hl)
;
0000029d d3e9
698
out
(scc_data),a
;and send it
0000029f 23
699
inc
hl
;point to the next byte
700
;
000002a0 3ec0
701
ld
a,0c0h
;reset eom latch command
000002a2 d3e8
702
out
(scc_cont),a
703 ;
000002a4 f3
704
di
;disable all int
000002a5 3e0a
705
ld
a,0ah
;select WR10
000002a7 d3e8
706
out
(scc_cont),a
707
;idle with 1’s
708
;at the end of the frame
000002a9 3ee8
709
ld
a,11101000b
000002ab d3e8
710
out
(scc_cont),a
711 ;
000002ad 3e00
712 txq2:
ld
a,00h
000002af d3e8
713
out
(scc_cont),a
;rr0
000002b1 dbe8
714
in
a,(scc_cont)
;read rr0
000002b3 cb57
715
bit
2,a
;read tx buffer empty
000002b5 28f6
716
jr
z,txq2
;loop if zero
000002b7717 txq1:
000002b7 7e
718
ld
a,(hl)
;
000002b8 d3e9
719
out
(scc_data),a
;and send it
000002ba 23
720
inc
hl
;point to the next byte
721
Application Note
Technical Considerations When Implementing LocalTalk Link Access Protocol
Page 285 of 316
UM011002-0808