SCI模块应用笔记（1）

UART，也就是异步串行通讯接口是单片机中最常见的外设，几乎每种类型的单片机都必备1到2个UART接口，9S12系列单片机也不例外。不过，摩托罗拉给他自己的单片机的串口起了个很有个性的缩写名称SCI（serialcommunicationinterface），其实就是我们常说的UART。

各种单片机串口的编程都大同小异，无非就是设置波特率、起始位、停止位、校验位等等。下面通过给出编程例子的方式分别介绍。

设置波特率

1. /**
2. *SettheBaudRateoftheSCI.
3. *@paramport,portcanbeSCI0/SCI1
4. *@parambaudRate,thewantedbaudrate.
5. *@parambusClk,TheSCImoduleclock.
6. */
7. voidSCISetBaudRate(unsignedcharport,unsignedlongbaudRate,unsignedlongbusClk)
8. {
9. unsignedshortbaudRateReg;
10. baudRateReg=(unsignedshort)(busClk/baudRate/16);
11. if(port==SCI0)
12. {
13. //HerewemustwriteBDHfirst!
14. SCI0BDH=(0x1f&(baudRateReg>>8));
15. SCI0BDL=(0xff&baudRateReg);
16. }
17. elseif(port==SCI1)
18. {
19. SCI1BDH=(0x1f&(baudRateReg>>8));
20. SCI1BDL=(0xff&baudRateReg);
21. }
22. else
23. {
24. //Somethingmustgowrong.Donothinghere!
25. }
26. }

设置奇偶校验位

1. /**
2. *Enable/DisableparityfunctionandsettheParitytype
3. *@paramportportcanbeSCI0/SCI1
4. *@paramisEnable0fordisableparityfunction,1forenable
5. *@paramtype0forEvenParity,1forOddParity
6. */
7. voidSCISetParity(unsignedcharport,unsignedcharisEnable,unsignedchartype)
8. {
9. if(port==SCI0)
10. {
11. SCI0CR1_PE=(isEnable&0x01);
12. SCI0CR1_PT=(type&0x01);
13. }
14. elseif(port==SCI1)
15. {
16. SCI1CR1_PE=(isEnable&0x01);
17. SCI1CR1_PT=(type&0x01);
18. }
19. else
20. {
21. //Ifcoderunhere,somethingmustgowrong.Donothinghere!
22. }
24. }

使能数据位的长度

1. /**
2. *SettheDataFormatModeBit
3. *@paramportportcanbeSCI0/SCI1
4. *@parambitsmustbe8or9
5. */
6. voidSCISetDataBit(unsignedcharport,unsignedcharbits)
7. {
8. if(port==SCI0)
9. {
10. switch(bits)
11. {
12. case8:
13. SCI0CR1_M=0;/*1startbit,8databits,1stopbit*/
14. break;
15. case9:
16. SCI0CR1_M=1;/*1startbit,9databits,1stopbit*/
17. break;
18. default:
19. //Ifcoderunhere,somethingmustgowrong.Donothinghere!
20. break;
21. }
22. }
23. elseif(port==SCI1)
24. {
25. switch(bits)
26. {
27. case8:
28. SCI1CR1_M=0;/*1startbit,8databits,1stopbit*/
29. break;
30. case9:
31. SCI1CR1_M=1;/*1startbit,9databits,1stopbit*/
32. break;
33. default:
34. //Ifcoderunhere,somethingmustgowrong.Donothinghere!
35. break;
36. }
37. }
38. else
39. {
40. //Ifcoderunhere,somethingmustgowrong.Donothinghere!
41. }
43. }

设置串口的工作模式

NORMAL_MODE是我们通常用的模式

LOOP_MODE是自发自收模式

SING_WIRE_MODE就是收发公用一条数据线的模式

1. /**
2. *Settheworkmodeofoperation
3. *@paramportportcanbeSCI0/SCI1
4. *@parammodemodecanbeNORMAL_MODE/LOOP_MODE/SING_WIRE_MODE
5. */
6. voidSCISetWorkMode(unsignedcharport,unsignedcharmode)
7. {
8. if(port==SCI0)
9. {
10. switch(mode)
11. {
12. caseNORMAL_MODE:
13. SCI0CR1_LOOPS=0;
14. SCI0CR1_RSRC=0;
15. break;
16. caseLOOP_MODE:
17. SCI0CR1_LOOPS=1;
18. SCI0CR1_RSRC=0;
19. break;
20. caseSING_WIRE_MODE:
21. SCI0CR1_LOOPS=1;
22. SCI0CR1_RSRC=1;
23. break;
24. default:
25. //Ifcoderunhere,somethingmustgowrong.Donothinghere!
26. break;
27. }
28. }
29. elseif(port==SCI1)
30. {
31. switch(mode)
32. {
33. caseNORMAL_MODE:
34. SCI1CR1_LOOPS=0;
35. SCI1CR1_RSRC=0;
36. break;
37. caseLOOP_MODE:
38. SCI1CR1_LOOPS=1;
39. SCI1CR1_RSRC=0;
40. break;
41. caseSING_WIRE_MODE:
42. SCI1CR1_LOOPS=1;
43. SCI1CR1_RSRC=1;
44. break;
45. default:
46. //Ifcoderunhere,somethingmustgowrong.Donothinghere!
47. break;
48. }
49. }
50. else
51. {
52. //Ifcoderunhere,somethingmustgowrong.Donothinghere!
53. }
54. }

设置SCI模块是否在Wait模式下工作

1. /**
2. *Enable/DisabletheSCIinwaitmode
3. *@paramportportcanbeSCI0/SCI1
4. *@parammodemodecanbeRUN_MODE/WAIT_MODE
5. */
6. voidSCISetPowerMode(unsignedcharport,unsignedcharmode)
7. {
8. if(port==SCI0)
9. {
10. switch(mode)
11. {
12. caseRUN_MODE:
13. SCI0CR1_SCISWAI=0;
14. break;
15. caseWAIT_MODE:
16. SCI0CR1_SCISWAI=1;
17. break;
18. default:
19. //Ifcoderunhere,somethingmustgowrong.Donothinghere!
20. break;
21. }
22. }
23. elseif(port==SCI1)
24. {
25. switch(mode)
26. {
27. caseRUN_MODE:
28. SCI1CR1_SCISWAI=0;
29. break;
30. caseWAIT_MODE:
31. SCI1CR1_SCISWAI=1;
32. break;
33. default:
34. //Ifcoderunhere,somethingmustgowrong.Donothinghere!
35. break;
36. }
37. }
38. else
39. {
40. //Ifcoderunhere,somethingmustgowrong.Donothinghere!
41. }
42. }

使能SCI模块的接收功能

1. /**
2. *Enable/DisableSCIReceiver
3. *@paramportportcanbeSCI0/SCI1
4. *@paramisEnable0disable1enable
5. */
6. voidSCIEnableRecv(unsignedcharport,unsignedcharisEnable)
7. {
8. if(port==SCI0)
9. {
10. SC