Freescale 9S12 系列单片机应用笔记（SCI）2

2. nsignedcharport,unsignedcharc)
3. {
4. SCI_RING_BUF*pbuf;
5. /*Obtainpointertocommunicationschannel*/
6. switch(port)
7. {
8. caseSCI0:
9. pbuf=&SCI0Buf;
10. break;

    caseSCI1:

11. pbuf=&SCI1Buf;
12. break;

    default:

13. return;
14. }
15. if(pbuf->RingBufRxCtr
16. {
17. pbuf->RingBufRxCtr++;/*No,incrementcharactercount*/
18. *pbuf->RingBufRxInPtr++=c;/*Putcharacterintobuffer*/
19. if(pbuf->RingBufRxInPtr==&pbuf->RingBufRx[SCI_RX_BUF_SIZE])
20. {/*WrapINpointer*/
21. pbuf->RingBufRxInPtr=&pbuf->RingBufRx[0];
22. }
23. }
24. }

25. //ThisfunctioniscalledbytheTxISRtoextractthenextcharacterfromtheTxbuffer.
26. //ThefunctionreturnsFALSEifthebufferisemptyafterthecharacterisextractedfrom
27. //thebuffer.ThisisdonetosignaltheTxISRtodisableinterruptsbecausethisisthe
28. //lastcharactertosend.
29. staticunsignedcharSCIGetTxChar(unsignedcharport,unsignedchar*err)
30. {
31. unsignedcharc;
32. SCI_RING_BUF*pbuf;

    switch(port)

33. {
34. caseSCI0:
35. pbuf=&SCI0Buf;
36. break;

    caseSCI1:

37. pbuf=&SCI1Buf;
38. break;

    default:

39. *err=SCI_BAD_CH;
40. return(0);
41. }
43. /*Seeifbufferisempty*/
44. if(pbuf->RingBufTxCtr>0)
45. {
46. pbuf->RingBufTxCtr--;/*No,decrementcharactercount*/
47. c=*pbuf->RingBufTxOutPtr++;/*Getcharacterfrombuffer*/
48. if(pbuf->RingBufTxOutPtr==&pbuf->RingBufTx[SCI_TX_BUF_SIZE])
49. {
50. pbuf->RingBufTxOutPtr=&pbuf->RingBufTx[0];/*WrapOUTpointer*/
51. }
52. *err=SCI_NO_ERR;
53. return(c);/*Charactersarestillavailable*/
54. }else{
55. *err=SCI_TX_EMPTY;
56. return(0);/*Bufferisempty*/
57. }
58. }

59. interruptVectorNumber_Vsci0voidSCI0_ISR(void)
60. {
61. charstatus;
62. unsignedchardata;
63. unsignedcharerr;
64. status=SCI0SR1;
66. if(status&0x0F)//0x1F=00011111,ifstatusisnotReceiveDataRegFullFlag
67. {
68. //Seeifwehavesomekindoferror
69. //Clearinterrupt(donothingaboutit!)
70. data=SCI0DRL;
71. }
72. elseif(status&0x20)//ReceiveDataRegFullFlag
73. {
74. data=SCI0DRL;
75. SCIPutRxChar(SCI0,data);//Insertreceivedcharacterintobuffer
76. }
77. elseif(status&0x80)
78. {
79. data=SCIGetTxChar(SCI0,&err);//Getnextcharactertosend.
80. if(err==SCI_TX_EMPTY)
81. {//Dowehaveanymorecharacterstosend?
82. //No,DisableTxinterrupts
83. SCI0CR2_SCTIE=0;
84. SCI0CR2_TCIE=0;
85. }
86. else
87. {
88. SCI0DRL=data;//Yes,Sendcharacter
89. }
90. }
91. }

    interruptVectorNumber_Vsci1voidSCI1_ISR(void)

92. {
93. charstatus;
94. unsignedchardata;
95. unsignedcharerr;
96. status=SCI1SR1;
98. if(status&0x0F)//0x1F=00011111,ifstatusisnotReceiveDataRegFullFlag
99. {
100. //Seeifwehavesomekindoferror
101. //Clearinterrupt(donothingaboutit!)
102. data=SCI1DRL;
103. }
104. elseif(status&0x20)//ReceiveDataRegFullFlag
105. {
106. data=SCI1DRL;
107. SCIPutRxChar(SCI1,data);//Insertreceivedcharacterintobuffer
108. }
109. elseif(status&0x80)
110. {
111. data=SCIGetTxChar(SCI1,&err);//Getnextcharactertosend.
112. if(err==SCI_TX_EMPTY)
113. {//Dowehaveanymorecharacterstosend?
114. //No,DisableTxinterrupts
115. SCI1CR2_SCTIE=0;
116. SCI1CR2_TCIE=0;
117. }
118. else
119. {
120. SCI1DRL=data;//Yes,Sendcharacter
121. }
122. }
123. }

最后给个例子说明用法:

1. #include/*commondefinesandmacros*/
2. #include"derivative.h"/*derivative-specificdefinitions*/
3. #include"sci.h"
4. #include"sci_buffered.h"

6. voidmain(void)

7. {
8. /*putyourowncodehere*/
9. unsignedcharC,err;
10. longl=0x1234L;
11. inti=0x5678;
12. CRGInit();
13. SCIInit(SCI0);
14. SCIInit(SCI1);
15. SCIBufferInit();
16. SCISetIEBit(SCI0,SCI_RIE);
17. SCISetIEBit(SCI1,SCI_RIE);

    EnableInterrupts;

18. SCIPutShortBigEndian(SCI1,i);
19. SCIPutShortLittleEndian(SCI1,i);
21. SCIPutLongBigEndian(SCI1,l);
22. SCIPutLongLittleEndian(SCI1,l);
23. for(;;)
24. {
25. _FEED_COP();/*feedsthedog*/
26. C=SCIGetCharB(SCI1,&err);
27. if(err==SCI_NO_ERR)
28. {
29. SCIPutCharB(SCI1,C);
30. }
31. }/*loopforever*/
32. /*pleasemakesurethatyouneverleavemain*/
33. }

34. 例子很简单，就不多解释了。

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