Ãëàâíàÿ/

Ðàäèîýëåêòðîíèêà, êîìïüþòåðû è ïåðèôåðèéíûå óñòðîéñòâà. /

Àðõèòåêòóðàââîäà-âûâîäà ïåðñîíàëüíûõ ÝÂÌ IBM PC

äëÿ îäíîãî¦ 0Bh   ¦

¦      ¦        ¦ èç êàíàëîâ ÏÄÏ                   ¦         ¦

¦      ¦        ¦                                  ¦         ¦

¦ 0D8h ¦ çàïèñü ¦ Î÷èñòêà (ñáðîñ) òðèããåðà-çàùåëêè  ¦ 0Ch   ¦

¦      ¦        ¦ (òðèããåðà ïåðâîãî/ïîñëåäíåãî)    ¦         ¦

¦      ¦        ¦                                  ¦         ¦

¦ 0DAh ¦ çàïèñü ¦ Ïðîãðàììíûé ñáðîñ êîíòðîëëåðà   ¦   0Dh   ¦

¦      ¦        ¦                                  ¦         ¦

¦ 0DCh ¦ çàïèñü ¦ Î÷èñòêà áèòîâ ìàñîê âñåõ  êàíàëîâ ¦ 0Eh   ¦

¦      ¦        ¦                                  ¦         ¦

¦ 0DEh ¦ çàïèñü ¦ Çàïèñü ðåãèñòðà ìàñîê äëÿ âñåõ 4-õ¦ 0Fh   ¦

¦      ¦        ¦ êàíàëîâ                          ¦         ¦

¦      ¦        ¦                                  ¦         ¦

¦ 0DAh ¦ ÷òåíèå ¦ ×òåíèå ðàáî÷åãî ðåãèñòðà ÏÄÏ    ¦   0Dh   ¦

¦      ¦        ¦                                  ¦         ¦

L------+--------+-----------------------------------+----------

           3. Ïðîãðàììèðóåìûé êîíòðîëëåð ïðåðûâàíèé

     Ïðîãðàììèðóåìûé  êîíòðîëëåð  ïðåðûâàíèé  (ÏÊÏ, Programmable Interrupt     Controller,   PIC)   ðåàëèçóåò        âåêòîðíóþ   ñèñòåìó

ïðåðûâàíèé.  Ìèêðîñõåìà  8259À  ôèðìû  Intel  (ñîâåòñêèé  àíàëîã ÊÐ580ÂÍ59),  à   òàê  æå  åå  ìîäèôèêàöèè   8259À-2  è  8259À-8, ïîääåðæèâàåò 8 óðîâíåé ïðåðûâàíèé îò âîñüìè ðàçëè÷íûõ óñòðîéñòâ. Îñíîâíûå ôóíêöèè êîíòðîëëåðà:

     -  ôèêñàöèÿ  çàïðîñîâ  íà   ïðåðûâàíèÿ  îò  âîñüìè  âíåøíèõ èñòî÷íèêîâ;

     - ïðîãðàììíîå ìàñêèðîâàíèå ïîñòóïàþùèõ çàïðîñîâ;

     - ïðèñâîåíèå  ôèêñèðîâàííûõ èëè öèêëè÷åñêè  èçìåíÿåìûõ ïðè­îðèòåòîâ âõîäàì êîíòðîëëåðà, íà êîòîðûå ïîñòóïàþò çàïðîñû;

     - èíèöèàöèÿ  âûçîâà ïðîöåäóðû îáðàáîòêè  ïîñòóïèâøåãî àïïà­ðàòíîãî ïðåðûâàíèÿ.

     Êîëè÷åñòâî  îáñëóæèâàåìûõ   âíåøíèõ  èñòî÷íèêîâ  ïðåðûâàíèé ìîæåò         áûòü óâåëè÷åíî    ïóòåì   êàñêàäèðîâàíèÿ   íåñêîëüêèõ

êîíòðîëëåðîâ.

      Ðàñïîëîæåíèå   âûâîäîâ    ìèêðîñõåìû êîíòðîëëåðà   8259A

ïðèâåäåíî íà ðèñóíêå.

            -------------¬  -------------¬

       __   ¦            L---            ¦

       CS  -¦ 1                       28 ¦-  Vcc

       __   ¦                            ¦

       WR  -¦ 2                       27 ¦-  A0

       __   ¦                            ¦  ____

RD  -¦ 3                       26 ¦-  INTA ¦                            ¦

       D7  -¦ 4                      25 ¦-  IR7

            ¦                           ¦

       D6  -¦ 5                      24 ¦-  IR6

            ¦                           ¦

       D5  -¦ 6                      23 ¦-  IR5

            ¦                           ¦

       D4  -¦ 7                      22 ¦-  IR4

            ¦                           ¦

       D3  -¦ 8                      21 ¦-  IR3

            ¦                           ¦

       D2  -¦ 9                      20 ¦-  IR2

            ¦                           ¦

       D1  -¦ 10                     19 ¦-  IR1

            ¦                           ¦

       D0  -¦ 11                     18 ¦-  IR0

            ¦                           ¦

     CAS0  -¦ 12                     17 ¦-  INT

            ¦                           ¦   __ __

     CAS1  -¦ 13                     16 ¦-  SP/EN

            ¦                           ¦

      GND  -¦ 14                     15 ¦-  CAS2

            ¦                           ¦

            L-----------------------------

------------T----------T---------------------------------------¬ ¦Îáîçíà÷åíèå¦Òèï âûâîäঠ            Íàçíà÷åíèå              ¦

+-----------+----------+---------------------------------------+ ¦  Vcc      ¦    - ¦  Ïèòàíèå + 5                 ¦

¦           ¦          ¦                                     ¦

¦  GND      ¦    -     ¦  Îáùèé (çåìëÿ)                      ¦

¦  __       ¦          ¦                                     ¦

¦  CS       ¦  âõîä    ¦  Âûáîð ìèêðîñõåìû                   ¦

¦  __       ¦          ¦                                     ¦

¦  RD       ¦  âõîä    ¦  ×òåíèå                             ¦

¦  __       ¦          ¦                                     ¦

¦  WR       ¦  âõîä    ¦  Çàïèñü                             ¦

¦           ¦          ¦                                     ¦

¦  D0-D7    ¦äâóíàïðàâ-¦  Âûâîäû íà øèíó äàííûõ              ¦

¦           ¦ëåííûå    ¦                                     ¦

¦           ¦âûâîäû    ¦                                     ¦

¦           ¦          ¦                                     ¦

¦ CAS0-CAS2 ¦ âõîäû/  ¦  Äëÿ âåäóùåãî êîíòðîëëåðà ÿâëÿþòñÿ  ¦

¦           ¦ âûõîäû   ¦  âûõîäàìè, äëÿ âñåõ âåäîìûõ âõîäàìè.  ¦

¦           ¦          ¦  Ïðåäíàçíà÷åíû äëÿ ïåðåäà÷è âåäóùèì ¦

¦           ¦          ¦  èíôîðìàöèè äëÿ âûáîðà íåîáõîäèìîãî ¦

¦           ¦          ¦  âåäîìîãî.                          ¦

¦ __ __     ¦          ¦                                     ¦

¦ SP/EN     ¦ âõîä     ¦  Âûáîð âåäóùåãî êîíòðîëëåðà         ¦

¦           ¦          ¦                                     ¦

¦ INT       ¦ âûõîä    ¦  Çàïðîñ íà ïðåðûâàíèÿ               ¦

¦ ____      ¦          ¦                                     ¦

¦ INTA      ¦ âõîä     ¦  Ïîäòâåðæäåíèå ïðåðûâàíèÿ           ¦

¦           ¦          ¦                                     ¦

¦   A0      ¦ âõîä     ¦  Âûáîð ðåãèñòðîâ êîíòðîëëåðà        ¦

¦           ¦          ¦                                     ¦

¦ IR0-IR7   ¦ âõîäû    ¦  Âõîäû çàïðîñîâ íà ïðåðûâàíèÿ îò    ¦

¦           ¦          ¦  âíåøíèõ èñòî÷íèêîâ.                ¦

L-----------+----------+----------------------------------------

     Â ñîñòàâ êîíòðîëëåðà âõîäÿò:

     - ñõåìà óïðàâëåíèÿ ÷òåíèåì/çàïèñüþ;

     - ñõåìà óïðàâëåíèÿ;

     - ñõåìà êàñêàäèðîâàíèÿ;

     - ðåãèñòð çàïðîñîâ íà ïðåðûâàíèÿ;

     - ñõåìà îáðàáîòêè ïðèîðèòåòîâ;

     - ðåãèñòð ñîñòîÿíèÿ;

     - ðåãèñòð ìàñêèðîâàíèÿ çàïðîñîâ íà ïðåðûâàíèÿ.

     ÏÊÏ ìîæåò íàõîäèòüñÿ â  äâóõ îñíîâíûõ ñîñòîÿíèÿõ: íàñòðîéêè è îáñëóæèâàíèÿ  çàïðîñîâ  íà  ïðåðûâàíèÿ.  Â ñîñòîÿíèè íàñòðîéêè êîíòðîëëåð    ïðèíèìàåò                óïðàâëÿþùèå    ñëîâà    èíèöèàëèçàöèè

(Initialization Command Words, ICW),  â ñîñòîÿíèè îáñëóæèâàíèÿ ­îïåðàöèîííûå óïðàâëÿþùèå  ñëîâà (Operation Control  Words, OCW). Âîçìîæíû íåñêîëüêî ðåæèìîâ îáñëóæèâàíèÿ èñòî÷íèêîâ ïðåðûâàíèé:

- ðåæèì ôèêñèðîâàííûõ ïðèîðèòåòîâ ïî ïî óðîâíÿì ïðåðûâàíèé; - äâà ðàçëè÷íûõ âàðèàíòà öèêëè÷åñêîãî ñäâèãà ïðèîðèòåòîâ;

- ðåæèì àâòîìàòè÷åñêîãî çàâåðøåíèÿ îáðàáîòêè ïðåðûâàíèÿ;

     - ðåæèì ñïåöèàëüíîãî ìàñêèðîâàíèÿ;

     - ðåæèì îïðîñà óñòðîéñòâ.

3.1.Îïèñàíèå îñíîâíûõ ýëåìåíòîâ ÏÊÏ

     Ñõåìà   óïðàâëåíèÿ  ÷òåíèåì/çàïèñüþ   (Read/Write  Control

Logic). Îñíîâíîé  ôóíêöèåé ýòîãî áëîêà ÿâëÿåòñÿ  ïðèåì êîìàíä îò ìèêðîïðîöåññîðà è ïåðåäà÷à åìó èíôîðìàöèè î ñîñòîÿíèè ÏÊÏ. Îáìåí ñ ìèêðîïðîöåññîðîì îñóùåñòâëÿåòñÿ  ÷åðåç ñïåöèàëüíûé 8-ðàçðÿäíûé áóôåð äàííûõ (Data Bus Buffer), ÿâëÿþùèéñÿ èíòåðôåéñîì ìåæäó ÏÊÏ è øèíîé äàííûõ.  ñîñòàâ  áëîêà âõîäÿò ðåãèñòðû óïðàâëÿþùèõ