Zilog Z16C35 Bedienungsanleitung PDF herunterladen (Seite 292)

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000002bb 10f0 722 djnz txq2 ;loop until all

723 ;bytes have been

724 ;transmitted.

725

726

000002bd 3e28 727 ld a,028h ;reset tx int pending

000002bf d3e8 728 out (scc_cont),a

729 ;note:tx buffer

730 ;empty happens as tx

731 ;shifter is loaded.

732 ;

733 ;count= last byte+

734 ;crc+ﬂag+12bit times-btdelay

735 ;btdelay=subr delay+ctc1int+polling=8bits

736 ;8+16+8+12-8=36=24h

000002c1 0e24 737 ld c,24h

000002c3 cdWwww 738 call bittime ;bittime delay

739 ;is stored in reg.c

740 ;

000002c6741 l7: ;timer ﬂag

000002c6 3aWwww 742 ld a,(timﬂg) ;

000002c9 cb4f 743 bit 1,a ;if bit1=1 then count ﬁnish

000002cb 28f9 744 jr z,l7 ;

000002cd cb8f 745 res 1,a ;reset timﬂg bit1

000002cf 32Wwww 746 ld (timﬂg),a ;update timﬂg

747 ;

000002d2 3e03 748 ld a,03h ;

000002d4 d3e5 749 out (ctc1_cont),a ;disable int,software reset

750 ;to kill counter

751 ;****disable rs-422 driver after 12 to 18 1’s*****

000002d6 3e05 752 ld a,05h ;select WR5

000002d8 d3e8 753 out (scc_cont),a

000002da 3e60 754 ld a,01100000b ;disable tx, set rts

000002dc d3e8 755 out (scc_cont),a

756

000002de 3e03 757 ld a,03h

000002e0 d3e8 758 out (scc_cont),a ;WR3

000002e2 3ecd 759 ld a,0cdh

000002e4 d3e8 760 out (scc_cont),a ;8b/char,rx crc enabled,

761 ;address search and rx enabled

762

763 ;*************************************

764

765 ;count for the interframe gap

766 ;of 200 usec or 46 bit times.

767 ;btdelay=subr delay+ctc1int+polling=8bits

768 ;46 - btdelay=46-8=26h

769 ;note that timﬂg will be polled in

770 ;the main routine.

771 ;

000002e6 0e26 772 ld c,26h

000002e8 cdWwww 773 call bittime

774 ;

775 ;bittime delay is stored in reg.c

776 ;*************************************

000002eb e1 777 pop hl ;restore

000002ec c1 778 pop bc ;restore

000002ed f1 779 pop af ;restore status and a reg

000002ee c9 780 ret

781

782

783

Application Note

Technical Considerations When Implementing LocalTalk Link Access Protocol

Page 286 of 316

UM011002-0808

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