Freescale 9S12 系列单片机应用笔记（SCI）2

首先是头文件:

1. /*sci_buffered.h*/

2. #ifndef_SCI_BUFFERED_H_

3. #define_SCI_BUFFERED_H_

   #defineSCI_RX_BUF_SIZE64/*NumberofcharactersinRxringbuffer*/

4. #defineSCI_TX_BUF_SIZE64/*NumberofcharactersinTxringbuffer*/

   #defineSCI_NO_ERR0/*Functioncallwassuccessful*/

5. #defineSCI_BAD_CH1/*Invalidcommunicationsportchannel*/
6. #defineSCI_RX_EMPTY2/*Rxbufferisempty,nocharacteravailable*/
7. #defineSCI_TX_FULL3/*Txbufferisfull,couldnotdepositcharacter*/
8. #defineSCI_TX_EMPTY4/*IftheTxbufferisempty.*/

9. /**
10. *Toobtainacharacterfromthecommunicationschannel.
11. *@paramport,portcanbeSCI0/SCI1
12. *@paramerr,isapointertowhereanerrorcodewillbeplaced:
13. **errissettoSCI_NO_ERRifacharacterisavailable
14. **errissettoSCI_RX_EMPTYiftheRxbufferisempty
15. **errissettoSCI_BAD_CHifyouhavespecifiedaninvalidchannel
16. *@returnThereceivedchariferr==SCI_NO_ERR
17. */
18. unsignedcharSCIGetCharB(unsignedcharport,unsignedchar*err);

    /**

19. *Tosendacharacteronthecommunicationschannel.
20. *ThecharactertosendisfirstinsertedintotheTxbufferandwillbesentby
21. *theTxISR.Ifthisisthefirstcharacterplacedintothebuffer,theTxISRwillbe
22. *enabled.IftheTxbufferisfull,thecharacterwillnotbesent(i.e.itwillbelost)
23. *
24. *@paramport,portcanbeSCI0/SCI1
25. *@returnCOMM_NO_ERRifthefunctionwassuccessful(thebufferwasnotfull)
26. *COMM_TX_FULLifthebufferwasfull
27. *COMM_BAD_CHifyouhavespecifiedanincorrectchannel
28. */
29. unsignedcharSCIPutCharB(unsignedcharport,unsignedcharc);

    /**

30. *Toinitializethecommunicationsmodule.
31. *Youmustcallthisfunctionbeforecallinganyotherfunctions.
32. */
33. voidSCIBufferInit(void);

    /**

34. *Toseeifanycharacterisavailablefromthecommunicationschannel.
35. *
36. *@paramport,portcanbeSCI0/SCI1
37. *@returnIfatleastonecharacterisavailable,thefunctionreturns
38. *FALSE(0)otherwise,thefunctionreturnsTRUE(1).
39. */
40. unsignedcharSCIBufferIsEmpty(unsignedcharport);

    /**

41. *ToseeifanymorecharacterscanbeplacedintheTxbuffer.
42. *Inotherwords,thisfunctionchecktoseeiftheTxbufferisfull.
43. *
44. *@paramport,portcanbeSCI0/SCI1
45. *@returnIfthebufferisfull,thefunctionreturnsTRUE
46. *otherwise,thefunctionreturnsFALSE.
47. */
48. unsignedcharSCIBufferIsFull(unsignedcharport);

    #endif

然后 是 c 文件.

1. /**

2. *SCI(SerialCommunicationInterface)BufferedSerialI/O
3. *@filesci_buffered.c
4. *@authorLiYuan
5. *@platformmc9s12XX
6. *@date2012-7-22
7. *@version1.0.1
8. */

9. #include"derivative.h"/*derivative-specificdefinitions*/
10. #include
11. #include"sci.h"
12. #include"sci_buffered.h"

    //#defineOS_ENTER_CRITICAL()_asm("pshc;sei")

13. //#defineOS_EXIT_CRITICAL()_asm("pulc")

    #defineOS_ENTER_CRITICAL()_asm("tpa;sei;staacpu_sr")

14. #defineOS_EXIT_CRITICAL()_asm("ldaacpu_sr;tap")

    /**

15. *DATATYPES
16. */
17. typedefstruct{
18. shortRingBufRxCtr;/*NumberofcharactersintheRxringbuffer*/
19. unsignedchar*RingBufRxInPtr;/*Pointertowherenextcharacterwillbeinserted*/
20. unsignedchar*RingBufRxOutPtr;/*Pointerfromwherenextcharacterwillbeextracted*/
21. unsignedcharRingBufRx[SCI_RX_BUF_SIZE];/*Ringbuffercharacterstorage(Rx)*/
22. shortRingBufTxCtr;/*NumberofcharactersintheTxringbuffer*/
23. unsignedchar*RingBufTxInPtr;/*Pointertowherenextcharacterwillbeinserted*/
24. unsignedchar*RingBufTxOutPtr;/*Pointerfromwherenextcharacterwillbeextracted*/
25. unsignedcharRingBufTx[SCI_TX_BUF_SIZE];/*Ringbuffercharacterstorage(Tx)*/
26. }SCI_RING_BUF;

    /**

27. *GLOBALVARIABLES
28. */

    SCI_RING_BUFSCI0Buf;

29. SCI_RING_BUFSCI1Buf;

30. /**
31. *Toobtainacharacterfromthecommunicationschannel.
32. *@paramport,portcanbeSCI0/SCI1
33. *@paramerr,isapointertowhereanerrorcodewillbeplaced:
34. **errissettoSCI_NO_ERRifacharacterisavailable
35. **errissettoSCI_RX_EMPTYiftheRxbufferisempty
36. **errissettoSCI_BAD_CHifyouhavespecifiedaninvalidchannel
37. *@returnThereceivedchariferr==SCI_NO_ERR
38. */
39. unsignedcharSCIGetCharB(unsignedcharport,unsignedchar*err)
40. {
41. unsignedcharcpu_sr;
43. unsignedcharc;
44. SCI_RING_BUF*pbuf;
46. /*Obtainpointertocommunicationschannel*/
47. switch(port)
48. {
49. c