8/6/2019 BTL Cam Bien
1/27
Bi tp lnK Thut Cm Bin (sensors)
ti: Thit k mch o nhit s
dng cm bin LM335GVHD:TS: Hong S Hng
Thc hin: Nhm etech-3i1. L Hc Phong KT-K53 20081958
2. Bi Quang Sng KT-K53 200821913. H Vn Vng KT-K53 200832224. Nguyn Vn Hng KT-K53 200812315. Hong Danh Vin KT-K53 20083121
1Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST),
8/6/2019 BTL Cam Bien
2/27
I. C s l thuyt
Nguyn l: Bin i nhit thnh in p. ogi tr in p trn s bit c gi tr nhit cno.
S khi mch o:
2Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST),
8/6/2019 BTL Cam Bien
3/27
Nhim v v hot ng ca tng khi:
Khi cm bin v chun ho tn hiu: c nhimv bin i nhit cn o thnh in p a vo khi chuyn i ADC.
Khi chuyn i ADC: c nhim v bin i
gi tr in p ra t khi cm bin thnh gi trs tng ng a vo khi tnh ton.
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST),
3
I. C s l thuyt
8/6/2019 BTL Cam Bien
4/27
Khi tnh ton v hin th: c nhim v c gitr chuyn i c bi khi ADC v tnh ton
ra gi tr nhit tng ng, sau hin thnhit trn ra LED 7 on.
Khi ngun: Cp ngun cho cc khi hotng. Trong mch s dng ngun in p
chun t bn ngoi, do khng cn thit kkhi ngun cho mch
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST),
4
I. C s l thuyt
8/6/2019 BTL Cam Bien
5/27
1. Cm bin LM335
LM335 l IC tch hp dng o nhit .Nguyn l ca n l da trn mc phncc ca lp chuyn tip p-n tuyn tnh theonhit mi trng. N gm c 3 chn: mt
chn cp ngun (ng thi l chn tn hiura), mt chn ni t v mt chn iu chnh.
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST),
5
II. Tm hiu cc linh kin c bn
8/6/2019 BTL Cam Bien
6/27
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST),
6
II. Tm hiu cc linh kin c bn
Cc thng s chnh:
Di o: -40 0C 100 0C
nhy: 10mV / 0K Sai s: 1 0C (Max l 2 0C)
Dng in lm vic:
0,4mA 5mA Tr khng u ra thp
(< 1)
8/6/2019 BTL Cam Bien
7/27
S kt ni:
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 7
II. Tm hiu cc linh kin c bn
8/6/2019 BTL Cam Bien
8/27
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 8
II. Tm hiu cc linh kin c bn
8/6/2019 BTL Cam Bien
9/27
2. ADC0809
ADC0809 l b chuyn i AD 8 bit hot
ng theo nguyn tc chuyn i xp x lintip.
Cc thng s chnh:
phn gii 8 bit. Dn knh vo 8 knh -> x l trc tip bt k
mt trong 8 knh Analog.
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 9
II. Tm hiu cc linh kin c bn
8/6/2019 BTL Cam Bien
10/27
Logic iu khin tng thch cc VXL, VK. Cc u vo gii m a ch c cht.
BUS d liu ra 3 trng thi, c cht. Tc chuyn i nhanh, chnh xc cao,
tiu th cng sut thp. Sai s LSB Cng sut tiu th: 15mW Ngun nui: 5V
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 10
II. Tm hiu cc linh kin c bn
8/6/2019 BTL Cam Bien
11/27
ADC0809 gm 8 knh u voanalog t IN1 ti IN7, ti mi thiim ch lm vic vi 1 knh. 3 tn
hiu C B A dng chn knh. iuchnh in p tham chiu ti 2 chnVref(+) v Vref(-). Chn OE (pin9)dng m b m d liu ra. ChnClock dng cp xung clock choADC0809 hot ng. Start l tnhiu bt u chuyn i v EOC ltn hiu bo kt thc chuyn i
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 11
II. Tm hiu cc linh kin c bn
8/6/2019 BTL Cam Bien
12/27
3. Vi iu khin AT89S52
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 12
II. Tm hiu cc linh kin c bn
8/6/2019 BTL Cam Bien
13/27
1. Khi cm bin v chun hoLM335 c nhy 10mV/0K, ngha l 0 0Cin p ra l 2.73V, do vy ta cn tr i 2.73V in p ra t l vi 0C.
Nu ta chn Uref ca ADC = 5V th phngii ca ADC l 5/256 20mV => phn
gii ca h thng l 20
C. gim phngii ta c th gim Uref v tng nhy choLM335
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 13
III. Thit k chi tit tng khi
8/6/2019 BTL Cam Bien
14/27
y ta chn Uref = 2.56V v tng nhyca LM335 ln 20mV/0C, khi nhy cah thng s l 0,5 0C. Do tn hiu ra cakhi cm bin s l:
Ura= 2(ULM335 -2.73)
=> ta thit k mt mch tr dng OPAM stho mn c yu cu trn.
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 14
III. Thit k chi tit tng khi
8/6/2019 BTL Cam Bien
15/27
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 15
III. Thit k chi tit tng khi
S nguyn l:
8/6/2019 BTL Cam Bien
16/27
2. Khi chuyn i ADC
Theo phn tch trn, Uref ta t bng 2.56V.
Ta dng mt bin tr tinh chnh chnh Urefcho ADC0809. Ta s dng knh 0 lm uvo tng t do C B A = 000, Trong mchs s dng IC NE555 lm mch to xung cp
cho ADC0809. Ta c c s nguyn lca khi nh sau:
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 16
III. Thit k chi tit tng khi
8/6/2019 BTL Cam Bien
17/27
S nguyn l khi chuyn i ADC:
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 17
III. Thit k chi tit tng khi
8/6/2019 BTL Cam Bien
18/27
3. Khi Tnh ton nhit v hin th
S dng VK AT89S52 tnh ton v hin
th nhit ln 4 LED 7 on Anode chung.S dng cng P0 c gi tr chuyn i tADC, cng P1 v P3 K v xut d liuln LED 7 on. P2.0 dng xut tn hiu
Start (bt u chuyn i). S nguyn lca mch nh sau:
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 18
III. Thit k chi tit tng khi
8/6/2019 BTL Cam Bien
19/27
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 19
III. Thit k chi tit tng khi
8/6/2019 BTL Cam Bien
20/27
Xy dng cng thc tnh ton nhit :
phn gii ca khi cm bin l 20mV/0C,
trong khi phn gii ca ADC l 10mV. Do khi nhit tng 1 0C th u ra ca ADCtng 2 n v => nhit t = N/2, N l gi trchuyn i bi ADC. Nhit c th hin th
l ti 0,5 0C.
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 20
III. Thit k chi tit tng khi
8/6/2019 BTL Cam Bien
21/27
S mch in v trongOrcad 9.2
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 21
III. Thit k chi tit tng khi
8/6/2019 BTL Cam Bien
22/27
Di y l mt s nguyn nhn gy ra sai scho mch o v cch gim sai s
Sai s do bn thn LM335 gy ra. Sai s do cc in tr trong mch chun ho
tn hiu. Gim sai s bng cch s dng ccin tr nhiu vch mu c sai s nh, hoc s
dng bin tr tinh chnh v s dng ng ho c chnh xc cao o chnh xc gi trin tr.
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 22
IV. Sai s ca h thng o
8/6/2019 BTL Cam Bien
23/27
Sai s do in p Offset ca cc vi mchkhuch i thut ton. Sai s ny c th gim
bng cch s dng cc vi mch khuch i
thut ton c chn chnh offset. Sai s do vi mch chuyn i ADC0809 to ra. Sai s do in p ngun khng n nh, dn
n cc in p chun cho mch tr, Uref choOPAMP cng khng n nh. Gim bng cchs dng nhng IC n p chnh xc cao.
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 23
IV. Sai s ca h thng o
8/6/2019 BTL Cam Bien
24/27
Sau qu trnh thc hin ti chng em tc nhng kt qu sau:
Thit k thnh cng s nguyn l v s mch in cho mch o nhit .
Thc hin gia cng mch in v lp rp thnhcng mch o nhit trong gii 0 100 0C.
Cc thnh vin trong nhm c thm nhiukinh nghim trong vic thit k cc mch intrn thc t.
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 24
V. Kt qu t c
8/6/2019 BTL Cam Bien
25/27
Trn c s ti o nhit trn chng ta cth m rng theo cc hng nh:
S dng ADC c phn gii cao tng chnh xc cho mch.
S dng ngun dng nui cho cm bin,gip tng khong cch t cm bin ti mch
o. Giao tip my tnh gip cho ngi dng c th
qun l nhit nhiu ni khc nhau.
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 25
VI. Cc hng m rng ti
8/6/2019 BTL Cam Bien
26/27
Kt hp thm mch iu khin nhit v ccthut ton iu khin lm nhit lun gin nh mt nhit nht nh hoc bmtheo mt quy lut no .
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 26
VI. Cc hng m rng ti
8/6/2019 BTL Cam Bien
27/27
Faculty of Electrical Eng., Hanoi Univ. ofScience and Technology (HUST), 27
Code chng trnh o nhit :