????????????????????????
????1.????????MCS-5l??????е????????п?????????????????????д??????????Χ?豸???紮?д??????CRT????????????????????
???????п???????????????????????
SM0 | SM1 | ??????? | ???? | ?????? |
0 | 0 | ???0 | ??λ?????????????????I/O??? | fosc/12 |
0 | 1 | ???1 | 8 λ???????????/?????? | ??? |
1 | 0 | ???2 | 9 λ???????????/?????? | fosc/1 ?? fosc/24 |
1 | 1 | ???3 | 9 λ???????????/?????? | ??? |
????2.??
?????????????????????????????????????????????????????????????????????????λ?????????ɡ?????????????????д????????????????????????????????????д???????????????? ?? ?????????? SBUF???????????? ?? 99H?????п??л?????????????????SCON??PCON???????????????п?????????????????????????????????????????1???ɡ?
????3.???п????????SCON
???????п????????SCON?????????
??????l????????????λSMO??SM1??SMO??SM1???????? ??1?? ???? ??0?? ??????????п?? 4??????????
??????2???????????λSM2??SM2=??1?? ?????????????????????????? 9λ?????1???????RI?á?1?? ???????ж????????λ???????0?? ???? RI???á?1?? ?????????????????Ч??
????SM2=??0?? ???????????????????????λ??????0????1?????????RI =??1???????????ж??RI???????塰0????SM2???????á?1?????塰0????
?????????????????????SM2?á?l??????????????????????????????????????????? SM2?塰0?????????????????????????????????????? 9λ???????0????
??????3?????????????λREN??REN=??1?? ????????????????REN =??0???????????REN???????á?1?????塰0????
??????4??????????D8λTB8??TB8????2?????3??????????λ???????????????д??1??0?????0?????1???á?
??????5??????????D8λRB8?????2?????3?У?????????????????λ???????RB8?????1?У???λ????RB8??
??????6???????ж???λTI?????????????????????TI?á?1???? TI???????????塰0????
??????7???????ж???λRI????????????Ч???????????RI?á?1???? RI???????????塰0?? ??
????4.???п????????? SBUF
???????п?????????SBUF??????????λ?????????????????????????????ɡ???????д??SBUF????????????????????????????TB8?????趨???????????????????????????????????????????????????????????SBUF?????á?1???? CPU????????CPU????????????????????????????????
????5.???п????????
??????1?????0???????λ????????
?????????????fosc/12
????RXD ???? ???????????
????TXD ???? ?????????λ????
????????/????????λRI/TI ???????SM2 = 0??
??????2?????1??8λUART
?????????????2 SMOD??T1????????/32 ?????
?????????10λ??
???????????Ч??????????λRI????????
????REN = 1??RI = 0 ??SM2 = 0????????9λ?????1??????????????SBUF??RI??1????9λ?????TB8?? RB8??
????6.??????
??????????????1???????????????????????256??????????00H??0FFH????????????????TTL?????????????????RS485?????????????????????????????????????????????9λ????TB8????????????????λ????????TB8 =??1?? ????????? TB8 =??0??????????? SM2?????á?1??????????????????????????????????????????????????????SM2=??1?????????????? RB8=??1????????????????????????Ч????????????????????????RI=??1?? ??????? CPU????ж??????????ж?????????????????????????????????????????SM2=??0????????? SM2 =??l????
????7.?????? ??
???????п??????????????????λ???????????? ???跢???λ????????????T, ??????? 1/T?? ??
????(1) ??0 ?????????????????????? 1/12, ????????????????????λ????? ????
????(2) ??2?????????????????PCON?????λSMOD??д????й?:??SMOD=0, ???????(1/64) f OSC ; SMOD=1, ?????????1/32??f OSC ??
????(3) ?? 1 ???? 3 ????????????SMODλ?й????, ??????? T1 ????????й?? ????? T1 ??????????????, ?????????? 2??8λ????????????, ?????? T1 ?ж????? TH1 ?????????????????, ???????????????????????? ????
????admin ?????????2018-05-08
