THIET KE VA Tffl CONG DONG HO THOI GIAN THlTC TU* DONG BAO G l 6 HOC U*NG DUNG VI DIEU K H I E N PIC
NGUYEN TU HA Tnrdng Dgi hoc Sir phgm - Dgi hoc Hue Tom tat: Bai bao trinh bay qua trinh thiet ke va thi cong mach dong ho thcri gian thuc (RTC- RealTime Clock) tu dong bao gia vao va ra tiet hpc su dung vi dieu khien PIC. Mach hien thi gid, phut, giay, thu, ngay, thang, nam va nhiet do bang Led 7 doan. Dir lieu thcri gian dugc doc tu IC thdi gian thuc DS12C887; dii lieu nhiet dp dugc dpc tir IC cam biln nhiet do LM35. Qua trinh doc du" lieu va hien thi thdi gian nhiet dp dugc dieu khien bdi vi dieu khignPICI6F877A.
Tu- khoa: Vi dieu khien PIC, dong ho thdi gian thuc.
I.DATVANDE
Ky thuat vi dieu khien hien nay phat trien rat manh me, no dugc iing dung vao rat nhieu ITnh vuc tir trong ddi song sinh hoat hang ngay {mach quang bao, mach chdng trdm, khda sd, tii lanh, ti vi) cho tdi cac linh vuc trong cong nghiep ciong nhu trong quan su.
Do cd nhieu uu diem nhu nhd gpn, kha nang lap trinh de dieu khien theo y mudn, gia thanh thap, co kha nang xu li dugc nhieu cdng viec nen vi dieu khien trd thanh linh kien khdng the thieu dugc trong cac thiet bi phuc vu con ngudi chiing ta.
Hp vi dieu khien PIC la mot tronp nhiing hg vi dieu khien mdi sau nay, cd rat nhieu uu diem vugt trpi so vdi cac hg vi dieu khien trudc do. Hien nay, cac trudng ky thuat da bat dau dua hp vi dieu khien PIC vao giang day va thuc hanh ciing nhu ung dung trong cac de tai khoa hpc (dac biet trong cac cudc thi ROBOCON sOr dung rat nhieu). Vi vay, viec nghien ciiu va iing dung hp vi dieu khien PIC la van de cap thiet can dugc quan tam.
Hien nay da co mot so trudng hpc sii dung mgch tu ddng bao gid hpc. Viec su dung mach nay giiip cho cac trudng hpc tiet kiem dugc cdng cu ngudi true theo doi gid de bdm chuong bao gid vao, ra tiet hgc. Tuy nhien van con rat nhieu trudng van chua lip dat mach bao gid tu ddng nay va cac mach tu ddng bao gid thuc te hien nay chti yeu sii dung cac linh kien, vi dilu khi^n don gian nen gay khd khan cho viec md rpng thiSt k^, thi cong. Tir nhu c5u thuc te do, cin den mach dong h6 thdi gian thuc va tu dong bao gid hpc sii dung vi dieu khien PIC vdi uu diem tiet kiem kinh phi, nang cao dp chinh xac, 6n dinh trong viec bao gid hpc va tien lgi khi sii dung.
2. Gldl THDEU VIDDEU KHIEN PIC
PIC la mpt hp vi dilu khiln RISC dugc san xuit bdi cdng ty Microchip Technology.
PIC bit ngu6n la chii viet tat cua "Programmable Intelligent Computer".
Hp vi dieu khien nay dugc sii dung rpng rai vi co cac uu diem:[l]De dang tim mua tai thi trudng Viet Nam vdi gia thanh khong qua dat; cd day dii cac tinh nang ciia mdt vi
Tap chi Khoa hpc va Giao dye, Trucmg Dai hgc Su pham Hu^
ISSN 1859-1612, S6 03(31)/2013: tr. 35-40
NGUYEN TU HA
dik khiJn khi hoat dong doc lap; sir hS trg ciia nha san xuat ve tnnh bien dich, cac eong cu lap trinh, nap ehucmg trinh tir don gian den phiic tap; cac tmh nang da dang eua vi dieu khiSn PIC va eac tinh nang nay khong ngimg dugc phat trieii; PIC la mgt su bj sung tat t6t vl kiSn thiie cflng nhu vS ung dung eho hg vi dieu khien mang tinh truyen thdng: hg vi dieu khien 8051.
Ngoai ra s6 luong ngucri su dung hg vi diSu khifc PIC hien nay tai Viet Nam cung nliu tren thi gioi rii rong rai. DiSu nay tao nhiSu thuan lgi trong qua trinh tim hieu va phat triln cac img dung nhu: s6 lugng tai lieu, s6 lugng cac ung dung mo da duge phat triSn thanh cong, dl dang trao ddi, hgc tap, di dang tim dugc sir chi dan khi gap kho khan.
Hirih l.Sado chdn ciia vi dieu khien PICl6F874A/16F877A
PIC sir dung tap lenh RISC. Tap lenh bao gom cac lenh tinh toan tren cae thanh ghi, voi cae hang so, ho3e eac vi tri bg nho, ciing nhu co cae lenh dieu kien, lenh nhay/ggi ham, va cac lenh de quay tra ve, no cung eo cac tinh nang phan eirng khac nhu ngat ho^c sleep {che do hoat dgng tiet kiem dien). Microchip cimg cap moi trucmg lap trinh MPLAB, no bao gom phan mem mo phong va trinh dich ASM. Mgt s6 eong ty khac xay dung cac trinh dich C, Basic, Pascal cho PIC [1].
De nap ehucmg trinh cho PIC, ta co the sir dung eac mach nap dugc cung cip bdi nha san xuat la hang Microchip hoac cae mach nap khac dugc thilt kl danh cho timg loai vi dilu khiln PIC.
Trong bai bag nay, chiing toi lira chgn su dung PIC16F877A. Day la vi dilu khiln thuot hg PIC16FXXX vdi tap lenh gdm 35 lenh co do dai 14 bit. M6i lenh diu duge thuc tbi hong mgt chu ki xung clock. Tdc do hoat dgng tdi da cho phep la 20 MHz voi mgt chu Id lenh la 200ns. Bg nho chuang trinh 8Kxl4 bit, bg nha dii lieu 368x8 byte RAM va bo nhd dii lieu EEPROM vdri dung lugng 256x8 byte. S6 PORT I/O la 5 voi 33 pin I/O. [2]
THIET KE VA THI CONG DONG HO THCil GIAN THUC TLTDONG BAG Gl6 HOC,
3. THIET KE MACH DONG HO THCil GIAN THUC RTC
Day la iing dijng sir dung vi d i l u khiln PIC de thiet ke mpt ddng ho dien tu treo tudng cd cac chiic nang sau:
Hien thi gid, phut, giay; thii, ngay, thang, nam; nhiet do;
Dieu chinh dugc gid, phiit, giay, thii, ngay, thang, nam;
Hen gid de bao chudng gid vao/ra tiet hgc theo yeu cau.
* So d6 khdi cua mach RTC:
Ku6i HI£N T H |
LED 7 BO.JN KHOI B * 0 GIO
KHOI DtEL K 1 I 1 £ N PlC16F877A KHAI THOI CIA-N THV-C
IC Dsiicsr
kHblHieU CHINH .VLT BAM KH6I DO NHI$T DO
iC LM3S Hinh 2. Sa do khdi mgch RTC
Khdi dieu khien se dpc du- lieu thdi gian va nhiet dp; sau do se hien thi len Led 7 doan.
Ddng thdi, mach dieu khien ludn kiem tra tin hieu tii nut bam de dieu chinh thdi gian hoac hen gid.
3.1. Khoi hieu chinh nut bam - Khoi do nhiet do
Mach sir dung 4 niit b i m de dieu chinh ddng hd gdm: niit chinh gid, niit hen gid, mit tang, mit giam. (Hinh 3)
LM35 la bp cam bien nhiet mach tich hgp chinh xac cao ma dien ap dau ra cua no ty le tuyen tinh vdi nhiet dp theo thang do Celsius [2]. Nhiet dp dugc xac dinh bang each do hieu dien t h i ngo ra cua LM35. (Hinh 4)
Hinh 3. Sodd ket ndi mit bdm Hmh 4. Sa do ket ndi LM35
NGLIYENTUHA
3.2. Khoi hiln thi
Mach su dung 16 LED 7 doan dl hiln thi thoi gian gio, phut, giay, thii, ngay, thang, nam va nhiet do. Dl dilu khiln cac LED 7 doan, chiing toi ket noi PORT D vdi cac chan DATA ciia LED 7 doan va su dung IC giai ma 74LS154 ket hgp vai Transistor*
dilu khiln sang LED. (Hinh 5)
Hinh 5. Sadd nguyen ly mgch hien thi LED 7 doan.
3.3. Khoi thoi gian thuc
DiJ lieu thcri gian se dugc cap nhat tir IC thdi gian thuc DSI2C887. Day la IC thdi gian thuc dugc san xuat bdi hang Dallas vgi mgt vai dac tinh eg ban sau: [2]
Chiia cac gia tri thcri gian giay, phiit, gid, thir, ngay, thang, nam vdi thcri gian hoat dgng dung den nam 2100;
Bg dem boat dgng vdi ±6i gian 10 nam neu khong co nguon dien ngoai cung cap;
Cac he thdng ben trong bao gdm he thong thdfi gian thirc, ngudn ngi bSng Lithium va bg tao dao dgng vgi bg chia tSn so dinh kem eho phep lap trinh dugc. Ngoai ra eon ho trg eac ngat phuc vu cho qua trinh xir li thdng tin cua h? thdng ben ngoai.
DS12C887 gom 24 chan va cd the dugc chia lam 3 nhom nhu sau:
Nhom chdn DATA: bag gdm cac chan AD7:AD0. Day la cac chan ma DS12C887 diing de dua dir lieu ra hay nhan dir lieu vao;
Nhom chdn diiu khiin giao tiip BUS: bao gom cae chan MOT, AS, DS, R/W vcii cac chiic nang phu thugc vao viec lira chgn chi do giao tilp BUS theo chuan ciia Intel (MOT= 1) hay Motorola (MOT= 0);
Nhom chdn chiic nang: bao gdm eae chan RESET (dung dl reset IC), IRQ (chan tac dgng ciia cac ngjt frong DS12C887) va chan SQW (chan tao sdng vugng ngo ta).
3.4. Khoi bao gio
Khdi bao gid se thuc hien chirc nang dd chuong dl bao gicr vag va ra tilt hgc. Dua vao thoi gian quy dinh tiet hgc eiia truorng, vi dilu khiln PIC se so sanh thai gian thuc va thoi gian vao va ra tiet hge. Neu thdi gian gidng nhau thi se dilu khiln dd chuong X bao gio.
THIET KE VA THI CONG DONG HO THCJl GIAN THUC Tl/ DONG BAO Gid HOC...
3.5. Khoi dieu khien
Khdi dieu khiln la mach gdm vi dilu khiln PIC 16F877A va cac cdng kit ndi dl giao tiep vdi cac khoi khac. (Hinh 6)
Hinh 6. Sa dd nguyen ly mgch dieu khien 4. XAY DT/NG CHLTONG TRINH CHO PIC
Dua vao thiet ke phan ciing, nguyen ly lam viec cua mach, chiing toi sit dung phan mem CCS viet chucfng trinh nap cho PIC de dieu khien mach [3]. Luu dd chuong trinh chinh duoc thuc hien nhu sau:
Chuong mnh baogic
Co Khen rao
Doc dau ni DS12CS87
Hirathi
1
- ^ Nut ^
^ fhifih gid iKhdnE Sao gio
TKhoog - " K : * dmc
Co Gk cUia lao
DSncS87
t
Chuong tnnh chinh g!0
Hinh 7. Liru dd chuang trinh chinh.
NGUYEN TU HA
5. KET QUA
Sau qua trinh thilt k l va thi edng mach, chiing to, da hoan 'hanh dong hd thdi gian ih^
cd chuc nang hr ddng bao gicr hgc nhu hinh 8. Ddng ho co the hien th. ehinh xacth™
gttSVa nhiet dd, ngoii ra - . ^ . W n a n r t u ddng bag gio hgc moi kht vao/ra tiet hgc.
Hinh 8. Bdng hd thdi gian thuc lu- ddng bdo^^^hoc.
6. KET LUAN
Mach ddng hd thdi gian thirc va hr dgng bag gig hoe sir dung vi d i l u khien PIC va IC chuyen dung DS12C887 cho ta dp chinh xae tuyet ddi ve thai gian thuc, boat dpng on dinh, lmh' boat. Mach cd thi ap dung rpng rai eho cae trudoig hpc hay cac co quan to ehlie cd nhu cau tu dpng bao gid.
Dl san phim nay them phong phu va tang hieu qua sii dung thi cdn phai phat trien thm cac chirc nang: hiln thi dugc ngay, thang, nam am lich; sir dung LED ma fain de hien thi dep han; thay ddi phucmg phap dilu khiln tir xa bang Remote,....
TAI LIEU THAM KHAO
[1] Website Diln dan dien tu (2012). Cff bdn vi vi diiu khien va PIC, tray cap ngay 20/08/2012, link; http://www.picvietoam.com.
[2] Website Tra ciiu Datasheet (2012). Datasheet P1C16F877A-DS12C887-LM1S- 74LS154, ttuy cap ngay 25/09/2012, link: http://www.alldatasheet.com.
[3] Ngo Dien Tap (2006). Vi diiu khiin v&i lap trinh C, NXB Khoa hoc ky thu?t.
Title: DESIGNING AND IMPLEMENTING THE REAL TIME CLOCK CIRCUIT THAT AUTOMATICALLY ALARMS THE SCHOOL TIME USING THE PIC MICROCONTROLLER
Abstract: In this paper, we show the process of design and implementation of the real time clock circuit that automatically alarms the beginning and the end of the school time using the PIC microcontroller. This circuit displays hour, minute second, day of week, day, month, year and temperature using LED 7- segment. The data of time is received from realtime DSI2C887 IC, and the data of temperature is received from the thermal sensor LM35 IC. The process of data analysis and display are controlled by the PIC 16F877A microcontroller.
Keywords: PIC MicroconnoOer, RTC- RealTime Clock.
ThS. NGUYEN Ttj HA
Khoa Vat K, Trucmg Dai hpc Su pham - Dai hoc Hui, Email: nguventuha82(a.gmail.com