Thit k thit b o in tim mini 1
LI GII THIU Trong cuc sng hin ti, nhu cu kim tra sc khe nh k ca
mi ngi ngy cng c nng cao. Vi s pht trin ca khoa hc cng ngh cng vi s
pht trin trong lnh vc in t gip con ngi c kh nng to ra c nhng sng
kin, sn phm phc v cho li ch ca con ngi mt cch thun tin hn. Sinh vin
ngnh K thut o v Tin hc cng nghip c trang b nhiu kin thc chuyn ngnh
v in, in t. Vi n mn hc Thit b o lng nhm i ti tng thit k mt thit b o
in tim vi thit k nh gn c kh nng di ng vi ng dng ca cng ngh vi x l
thay cho cc kt cu thanh ghi, bng giy cng knh ca cc thit b o in tim
c in. c s hng dn tn tnh ca thy Nguyn Anh Tun, nhm n xin c la chn
ti: THIT K THIT B O IN TIM MINI Do thi gian ngn v kinh nghim thc t
cha c nhiu nn ti khng trnh khi s gin n v cc khim khuyt. Mong c thy
tip tc ch dn v gp nhm c th i ti kt qu cui cng l thit k ra c thit b
o in tim mini c th ng dng rng ri trn th trng. Qua y, mt ln na xin c
gi li cm n chn thnh ti cc thy c gp , gii p thc mc cho nhm v c bit l
s hng dn chi tit, tn tnh ca thy Nguyn Anh Tun gip cho nhm hiu ra c
thm rt nhiu iu phc v cho qu trnh hc tp, lm vic sau ny. Qu trnh thc
hin ti theo s hng dn ca thy Nguyn Anh Tun nhm tin hnh phn cng v thc
hin cng vic chnh nh sau: NGUYN B BIN THANH HI CHU MINH HUN Thit k v
thi cng mch cng H tr phn c s d liu trn giao din my tnh Lp trnh phn
mm trn vi x l Thit k v lp trnh phn giao din Visual Basic H Ni, thng
7 nm 2009 Nhm thc hin
2 n Thit b o
MC LC LI GII
THIU.........................................................................................................1
MC
LC....................................................................................................................2
Danh mc hnh
v:.......................................................................................................4
Danh mc t vit
tt:...................................................................................................4
1. Tng quan ti thit k thit b o in tim
mini..................................................5 2. Thit k
mch u vo thu thp tn hiu in
tim....................................................52.1. S lc v
tn hiu in
tim..................................................................................5
2.2. in cc v cp bc kim chng
nhiu..................................................................6
2.3. Mch khuch i Vi
sai.........................................................................................7
2.4. Mch iu khin chn
phi...................................................................................7
2.5. Mch lc thng
cao..............................................................................................9
2.6. Mch lc thng
thp.............................................................................................9
2.7. Mch khuch i
lp..........................................................................................10
3. Thit k b ngun cho mch o v mch iu
khin.............................................113.1. Tnh ton
thit k ngun +/-9V cho khuch i thut
ton................................11 3.2. Thit k ngun 5V cho vi iu
khin v cc modul khc trn mch...................12
4. S dng vi iu khin ly mu v x l tn hiu in
tim..................................134.1. Tng quan v phn cng vi x
l.......................................................................13
4.2. Lp trnh phn
mm...........................................................................................13
5. Kt ni mch vi my tnh, thit k giao din chc nng trn my
tnh................155.1. Giao din ca chng trnh c vit trn Visual
Basic 6.0 ..............................15 Yu cu i vi phn giao din
trn my tnh.......................................................15
Thc hin ci t cc thng s kt ni vi mch cng theo chun truyn tin
RS232....................................................................................................................15
Thc hin vic v li th in tim t cc gi tr o c ca mch cng..........15
Thc hin vic lu tr thng tin o vo c s d liu trn my
tnh.....................15 Cc chc nng ca chng
trnh...........................................................................15
5.2. Lu tr cc s
liu..............................................................................................17
Thit k thit b o in tim mini 3Phn mm trn my tnh qun l d liu lin
quan bng th vin DAO (Data Access Objects). Cc thng tin cn thit v
ngi o in tim c lu li nh l: H v tn, m lu tr, ngy o, ch thch c phn mm
lu li trn mt file mdb (nh dng file d liu ca Microsoft Access) nm
trong th mc cha chng trnh. Ngoi ra mt iu rt quan trng chnh l cc d
liu v tn hiu in tim cng c phn mm thc hin lu li trn cc file *.ECG vi
tn file chnh l m lu tr. Vic to ra file t nhng d liu nhn c t mch o c
thc hin bng vic s dng m hnh FSO (File System Object). Nhng file ny
c lu tr trong th mc data nm cng vi file chy phn mm. D liu t cc file
ny d dng c truy xut v tin hnh v li th in tim o c sau khi c yu cu
(nhn vo nt XEM trn ca s qun l d
liu).....................................................................................................18
5.3. Thc hin m phng phn mm v nhn
xt.....................................................18 Thc hin m
phng phn
mm...........................................................................18
nh gi nhn xt v phn
mm..........................................................................19
6. Kt lun v mt s kt qu ca mch o in
tim.................................................19 Tng hp mt s
ti liu tham
kho:....................................................................22
4 n Thit b o
Danh mc hnh v: Hnh 2.1: Hnh dng v thng s ca tn hiu in tim thng
thng Hnh 2.3: Mch iu khin chn phi Hnh 2.2: S khuch i vi sai s dng
AD620 v mch iu khin chn phi Hnh 2.1: Hnh dng v thng s ca tn hiu in
tim thng thng Hnh 2.4: S mch lc thng cao Hnh 2.5: S mch lc thng thp
Hnh 2.6: S thit k mch khuch i lp Hnh 3.1: S nguyn l mch ngun Hnh
3.2: Hnh dng ca in p ra sau cu diode Hnh 5.1: th in tim mu v bng
Teechart Hnh 5.2: in p o c sau khi tr offset Hnh 5.3: Form lu tr v
qun l thng tin Hnh 5.4: S m hnh m phng trn Proteus Hnh 6.1: Kt qu
test phn cng vi LCD v phm bm Hnh 6.2: Phn p in p xoay chiu 12V ly
in p 1.2mV Hnh 6.3: Tn hiu hnh sin qua b khuch i v lc ( c b offset)
Danh mc t vit tt: T vit tt T y ECG Electrocardiogram LA Left Arm RA
Right Arm RL Right RL DRL Driven Right Leg LCD Liquid Crystal
Display IC Intergrated Circuit UART Universal asynchronous
receiver/transmitter ADC Analog/Digital Converter VB Visual Basic
PC Personal Computer VK Vi iu khin DAO Data Access Object FSO File
System Object RTC Real Time Clock Ngha ting Vit in tim Tay tri Tay
phi Chn phi Mch iu khin chn phi Mn hnh tinh th lng Vi mch tch hp B
thu/pht khng ng b a nng B chuyn i tng t/s Phn mm Visual Basic My
tnh c nhn i tng qun l d liu i tng tp tin h thng ng h thi gian
thc
Thit k thit b o in tim mini 5
1. Tng quan ti thit k thit b o in tim mini Thit k mch o in tim
vi kh nng o ng chuyn o chnh LA-RA: S dng 3 in cc gn tay tri, tay
phi v chn phi o ng chuyn o LA-RA ca tn hiu in tim. C kt hp mch iu
khin chn phi (DRL). Thit b c kh nng a ra c cc thng s v tn hiu in
tim nh: o Tn s nhp p
o Ngng in p cao nht, thp nht, cc khong thi gian ca cc sng P, S,
R. o tim Nhn dng mt s trng hp c bn v s bt thng ca in
Khi vi iu khin m nhim chc nng thu thp tn hiu in tim, c mn hnh
LCD hin th thng s in tim v giao din nt chn la chc nng.
Thit b c giao tip vi my tnh truyn tn hiu in tim v my tnh phc v
hin th, lu tr, chn on
2. Thit k mch u vo thu thp tn hiu in tim 2.1. S lc v tn hiu in
tim Tn hiu in tim (i vi o trnh Tay tri Tay phi) c hnh dng chun nh
hnh v sau:
6 n Thit b o
Hnh 2.1: Hnh dng v thng s ca tn hiu in tim thng thng Gi tr bin
ln nht thuc v sng R (1.2-1.5mV) do a v in p chun qua ADC x l cn
khuch i tn hiu ln khong 1000-2000 ln. Chu k ca tn hiu in tim nm
trong khong 60-300BPM (tng ng 1-5Hz), tuy nhin di tn cn quan tm x l
tn hiu in tim l khong t 0.1Hz-150Hz (theo quy c thng dng trong vic
thu thp x l tn hiu in tim). 2.2. in cc v cp bc kim chng nhiu Do tn
hiu in tim rt nh (c milivolt) nn n rt d b nh hng bi cc yu t nhiu t
bn ngoi nh in t trng, nhit do vic s dng dy no ni in cc o vi mch o l
mt yu t quan trng. Trong ti ny cp ng mm mt li v PVC c bc kim c s
dng loi tr cc nh hng ca in t trng ngoi ti tn hiu in tim khi n truyn
trn dy dn. in cc in tim c la chn l in cc dn chng loi MEDI-TRACE 210
ca hng KENDALL. y l loi in cc s dng mt ln vi cu to Ag/AgCl (u kim
loi lm t bc v lp tip gip vi da c lm t mt loi keo hn hp dn in vi
thnh phn cha AgCl).
Thit k thit b o in tim mini 7 2.3. Mch khuch i Vi sai
Hnh 2.2: S khuch i vi sai s dng AD620 v mch iu khin chn phi
AD620 l IC khuch i vi sai cho cht lng cao. Vi kh nng d dng iu chnh
h s khuch i t 1 cho ti 1000 bng cch thay i gi tr in tr khuch i t vo
gia ca hai phn t khuch i thut ton nm bn trong IC (c ni ra ngoi qua
chn 2 v chn 8). Dng bias u vo ti a l 1nA, c tnh khuch i t ph thuc
vo nhit (in p offset ti a 0.6V/C). H s khuch i ca AD620 c tnh bng
cng thc:G= 49.4 k 49.4k + 1 R G = RG G 149 .4 +1 = 5.94 6 10
Vi s la chn RG = 3.3K ta c h s khuch i qua AD620 l:G1 =
2.4.
Mch iu khin chn phi Trong qu trnh o in tim, tn ti mt in p Vc gia
im trung tnh trn c th ngi v im trung tnh trn mch o. iu ny dn n vic
tn hiu in tim thu c b lch khi ng c s. trnh hin tng tri im khng
trong qu trnh o in tim ngi ta thng dng mt mch iu khin chn phi (ni
vi mt in cc gn vo chn phi) nhm mc ch gim in p chnh lch Vc. Tuy nhin
nu khng m bo c s cch ly vi in khng ln dng in chy qua in cc ny c th
gy nguy him ti ngi s dng.
8 n Thit b o
Hnh 2.3: Mch iu khin chn phi Quan st trn hnh 2.3 ta thy c in th
gia trung tnh ca mch o (Vo) v trung tnh ca ngi (Vc) ca khuch i U1
(OP07) c quan h nh sau: vC vO = R1 id vi id l dng in chy t mch o vo
chn phi.1 3 4 2 Mt khc ta li c vO = ( R PR ) vC vC = R + ( R PR ) i
d do gim c in 3 4 2 3 4
R
R ( R PR )
p chnh lch Vc ta phi chn la R1,R2,R3,R4 sao cho vi i d cho trc
th Vc phi nh hn mc quy nh. Theo tiu chun in tim quy c quc t dng id
thng mc nh hn 20A (vi dng >5mA trong khong thi gian 200mS c th
gy sc cho tim). Vi nhng gi tr in tr la chn trn hnh v ta tnh c: vC
47 V . Khi ch cn b sai lch tnh tng ng vi 47 V (hoc b qua nu khng cn
thit) th tn hiu in tim thu c s trnh c hin tng tri im khng khi o. T
in C1 mc ni tip vi R5 nhm mc ch lc nhiu cao tn khi chy qua mch iu
khin chn phi.
Thit k thit b o in tim mini 9 2.5. Mch lc thng cao
Hnh 2.4: Mch lc thng cao i vi tn hiu in tim, tn s cn quan tm nm
trong khong 0.05Hz ti 150Hz. Do b lc thng cao phi p ng cho php tn
hiu vi tn s >0.05Hz i qua. p ng c iu ny la chn tt nht l mch lc
thng cao RC. Cng thc tnh tn s ct nh sau:1 1 = = 0.04823Hz 0.05Hz 2
RC 2 3.3 10 6 10 6 H s khuch i qua mch lc thng cao l: G2 = R 20 /
R19 = (33+ 10) /10= 4.3 fc =
2.6.
Mch lc thng thp
Hnh 2.5: S mch lc thng thp Mch lc thng thp cng s dng mch lc RC
bc 1. Tn s ct c tnh ra nh sau:
10 n Thit b o
fc =
1 1 = = 146.148Hz 150Hz 2 RC 2 3.3 10 3 0.33 10 6
H s khuch i tn G3=R10/R11=(330+10)/10=34. 2.7.
hiu
sau
khi
qua
mch
lc
ny:
Mch khuch i lp Do tn hiu in tim l tn hiu xoay chiu trong khi ADC
ca PIC ch c kh nng ly mu cc tn hiu nm trong khong t 0V Vref cho nn
phi thit k mch khuch i lp c tc dng iu chnh offset cho tn hiu in tim
sau mch khuch i v dng in p trong khong t 0V-Vref. Mch khuch i la
chn trong trng hp ny l mch khuch i vi sai n gin. S dng khuch i thut
ton OP07 cho cht lng p ng rt tt.
Hnh 2.6: S thit k mch khuch i lp S ny l s mch khuch i vi sai hai
tn hiu vo. Vi cc thng s linh kin la chn trn hnh v th in p ti
ECG_OUT c tnh theo cng thc:R16 R2 R16 )+ 5 Vecg _ s 2adc R15 R1 + R
2 R15 V 0 = (5 Vecg _ s 2adc ) / 2 V 0 = (1 +
Tm li: H s khuch i i vi tn hiu in tim sau khi qua mch chun ha l:
G = G1 G 2 G3 = 6 4.3 34 = 877 .2 Nh vy tn hiu in tim c a v dng
chun vi bin max bng 0.5 (5 Vecg _ 2adc ) . Vi tn hiu in tim dao ng
trong khong 1.5mV th bin tn hiu dao ng trong khong t 1.18 V n
3.81V
Thit k thit b o in tim mini 11 3. Thit k b ngun cho mch o v mch
iu khin 3.1. Tnh ton thit k ngun +/-9V cho khuch i thut ton m bo c
s hot ng chnh xc cho cc IC khuch i thut ton th vic cch ly ngun cung
cp cho n khi cc thit b khc l cc k quan trng. V l do phi thit k mch
ngun ring cp cho cc IC khuch i thut ton trong mch.
Hnh 3.1: S nguyn l mch ngun Ngun c ly t in p 220VAC/50Hz. Sau
khi a qua bin p ly c gi tr in p +15VAC/-15VAC(50Hz), gi tr ny l gi
tr hiu dng ca tn hiu. Gi tr nh ca in p ny sau chnh lu cu i-t l VP =
15 2 2 0.7 = 19.8V (trong 0.7 l st p qua mi i-t ca cu). Do mch ngun
ch cung cp cho 5 IC khuch i thut ton trn mch nn dng yu cu l khng
ln. Ta thit k mch ngun c th cung cp in p +/-9V vi dng in ti a l
200mA. Cu to ca IC n p h 78xx v 79xx ch hot ng khi in p u vo ln hn
in p u ra t 1,6V tr ln. Cng thc tnh gi tr t b san phng hnh dng in p
sau cu diode nh sau:C= I LOAD t Vi ILOAD l dng cung cp ti a cho
php, VRIPPLE l khong dao VRIPPLE
ng ca in p u vo trc IC n p. t l khong thi gian gia hai nh ca in
p. Vi tn s ngun xoay chiu 50Hz th t=0.01s
12 n Thit b o
C =
0.2 0.01 = 400.10 6 F Trn thc t ta la chn t in 470 F /50V. Khi
5
in p VRIPPLE =4.26V. Mc in p u vo IC n p l (15.54V19.8V) tho mn
iu kin hot ng ca IC n p.
Hnh 3.2: Hnh dng ca in p ra sau cu diode loi tr nhiu ngun (tn s
50Hz v cc hi bc cao) ta s dng t Cf=47F mc vo mch pha sau IC n p. T
C c tc dng dn ton b tn hiu nhiu xoay chiu i qua gi li thnh phn mt
chiu cung cp ti cc linh kin khc trn mch. 3.2. Thit k ngun 5V cho vi
iu khin v cc modul khc trn mch. Nhm to s cch ly, trnh nh hng ca cc
phn t khc trn mch ti phn khuch i tn hiu, mch ngun 5V thit k cp ngun
cho vi x l v cc thit b ngoi vi khc c tch khi ngun +/-9V nh hnh v
3.1.
Thit k thit b o in tim mini 13 4. S dng vi iu khin ly mu v x l
tn hiu in tim 4.1. Tng quan v phn cng vi x l4.1.1.
PIC16F877A:
Vi mt ti nh trn chng ta s dng kh nhiu cc chun giao tip,nh chun
I2C cho ng h thi gian thc, chun UART cho truyn thng vi my tnh v
truyn thng vi thit b qut m vch.Ngoi ra chng ta s dng thm phn s l
ADC v th nn yu cu t ra vi vi iu khin l cng tch hp c cc phn th cng
vic s phc tp hn.Chip pic 16F877A c tch hp b ADC (10bit),tch hp c cc
chun giao tip nh:I2C,SPI,UART ,v c 5port in/out c th p ng c yu cu t
ra vi 1 mch ta c th th nghim c. i n sn phm hon chnh th vn t ra y l
thit b t c nhiu yu cu v cht lng cng nh v tin dng. Pic 16F877A c kch
thc tng i ln khng ph hp vi thit b nh gn, hng pht trin i n sn phm l
s thay chip pic bng chip dn nh PSOC, atmega128. 4.1.2. Hin th thi
gian: DS1307 l IC ng h thi gian thc m thi gian, c tc dng truyn tn
hiu cho vi iu khin x l hin th thi gian.V DS1307 s c ni vi thch anh
tn s 32.768kHz to tn hiu . 4.1.3. Giao tip vi my tnh Cng Com ca my
tnh theo chun RS232 ( mc 1 c in p -3V ti -25V v mc 0 c in p 3V ti
25V) nn cn s dng IC MAX232 ng b tn hiu gia giao tip UART v chun
RS232. 4.1.4. Bn phm 4 phm c kt ni vi Vi x l qua IC74LS148 c x l
bng phng php qut phm. 74LS148 l IC gii m 8 u vo 3 u ra c bo ngt khi
u vo thay i. 4.1.5. LCD La chn LCD DM1602A(16x2) hin th. V do yu cu
v s chn iu khin nn LCD s c lp trnh theo kiu 4bits data. 4.2. Lp
trnh phn mm thun tin cho vic kim tra, nhm thit k chng trnh hin th
cc modul iu khin qua LCD , v thng qua bn phm ta chn cc ch iu
khin.
14 n Thit b o
Giao din chnh hin th trn LCD: 0.Menu 0.1: SENSOR 0.2: Time 0.3:
COM-PC 0.1.1: Hin th gi tr sensor 0.2.1: Hin th Time (Trn LCD)
0.3.1: Chng trnh kt ni vi PC. Thc hin tng trn nhm s dng vi x l
16F877A v s dng ngn ng lp trnh C trong mi trng CCS.Trong mi trng
CCS h tr mt s hm chun:
Delay,Read_ADC(mode),SPI_Write,SPI_Read,I2C_Write v mt s lnh thng
dng khc (xem thm ph lc). chy chng trnh trn pic ta dng 4 phm bm trn
mch . Gi tn cc phm bm l Enter, esc, up, down . Dng 4 phm ny la chn
cc ch chy ca pic, ch chy ny s c hin th tng ng LCD. B cc chng trnh
ca pic: lp ngoi cng l menu, lp con ca menu tng ng l cc lp : quy
trnh , time, buffer. Cng vic ca cc lp: Kch bn chy phn mm: - Init cc
chng trnh con cn thit. - Nhn lnh iu khin c in tim t my tnh hoc nhn
nt bt u qu trnh o in tim. Tnh ton thi gian thc hin lnh ph hp vi tn
s ly mu cn thit ca tn hiu o. Time: hin th thi gian ln LCD. Buffer :
Phn d phng , dng chy th cc tnh nng b sung. Mt s void chnh ca chng
trnh: 1. Chng trnh menu cho LCD: void menu() Mc ch: Hin th ton b
menu trn LCD 3. Modul bn phm : ni hm
Thit k thit b o in tim mini 15 Scan_key(); Mc ch: qut xem phm no
c bm tr li gi tr tng ng v hm. 4. Modul RTC Void RTC(); Mc ch: c gi
tr trn DS1307 ,lu gi tr gi vo bin RTC_hour, gi tr pht vo bin
RTC_Min. 5. Kt ni mch vi my tnh, thit k giao din chc nng trn my tnh
5.1. Giao din ca chng trnh c vit trn Visual Basic 6.0 Yu cu i vi
phn giao din trn my tnh Thc hin ci t cc thng s kt ni vi mch cng
theo chun truyn tin RS232. Thc hin vic v li th in tim t cc gi tr o
c ca mch cng. Thc hin vic lu tr thng tin o vo c s d liu trn my tnh.
Cc chc nng ca chng trnh. thc hin cc yu cu ra th Visual Basic l mt
la chn hp l. Trn nn Visual Basic c rt nhiu cc cng c h tr thc hin cc
yu cu chnh nh ra trn. thc hin giao tip vi mch cng theo chun RS232
ta s dng th vin giao tip RS232 MSCOMM32.OCX ca Microsoft. Vic v th
in tim ln giao din s dng th vin Teechart v n cung cp hu ht cc dng
th biu c 2D v 3D vi ha kh p, la chn bng cch ko-th cc k trc quan. Bn
cnh l cc h tr cc k chi tit, ngi dung c th tc ng v bt k thng s no ca
hnh bng c cc ci t cng ( t trc tip trn ca s Editing) hoc ci t mm
(thao tc trn phn lp trnh) Cng ni tip c kh nng ty chn t COM 1 n COM
8 (thng trn my tnh ch c COM1 l cng vt l). Tc truyn c th c la chn
nhiu mc khc nhau t 2400bps ti 115200bps. Ty theo vo khong cch v iu
kin truyn m ta chn tc cao thp khc nhau. V khung truyn d liu gia PC
v VDK c mc nh l chun truyn 11bits (1bit Start, 8bits data, 1bit
Stop, 1 bit Priority). Kim tra li kiu chn l. Phn mm cho php la chn
thit lp bt tay vi mch cng (Handshaking) vi cc loi: RTS/CTS,
XON/XOFF, BOTH RTS/XONXOFF v NONE Hnh nh ca sng in tim c th hin
theo dng trc ta A=f(t).
16 n Thit b o
Vi: A l bin ca sng in tim o bng mV, t l ln ly mu Khi chng trnh c
khi ng s yu cu ngi dng chn cc thng s cho kt ni nh tc truyn (bauds)
v tn cng COM thc hin kt ni, nh dng khung truyn(8 hoc 9 bits d liu),
ch bt tay, kiu truyn (Text hoc Binary). Sau khi ci t kt ni, chng
trnh s c khi ng s lin tc nhn s liu t cng com thc hin chun ha gi tr
nhn c v v n trn mn hnh. Vi dng sng in tim Teerchart t ra kh li
th
Hnh 5.1: th in tim mu v bng Teechart Sau khi tin hnh thit lp cho
cng com. Phn mm trn my tnh s ch i d liu gi ln t vi x l v tin hnh v
ra th ca tn hiu thu c thng qua d liu nhn c. Vic chun ha tn hiu in
tim cng l vn yu cu phn mm phi thc hin. Tn hiu in tim (o trnh tay
tri tay phi) l mt tn hiu xoay chiu. a vo ADC trong vi x l
PIC16F877A ly mu th mch khuch i a tn hiu v dng chun dao ng trong
khong t 0-5VDC cho nn khi biu din trn th my tnh cn phi xc nh c v tr
0V ca tn hiu.
Thit k thit b o in tim mini 17
Hnh 5.2: in p o c sau khi tr offset Bng cch chp 2 in cc ni vi
tay tri v tay phi ri tin hnh ly mu ta s thu c gi tr offset do mch
khuch o to nn i vi tn hiu in tim. Phn mm s t ng b gi tr offset ny
bng cch tr i vo d liu nhn c ri mi tin hnh v th. 5.2. Lu tr cc s liu
thun tin trong vic kim sot thng tin v ngi o in tim v cc thng s in
tim o c th d liu s c phn mm lu li trn my tnh.
Hnh 5.3: Form lu tr v qun l thng tin
18 n Thit b o
Phn mm trn my tnh qun l d liu lin quan bng th vin DAO (Data
Access Objects). Cc thng tin cn thit v ngi o in tim c lu li nh l: H
v tn, m lu tr, ngy o, ch thch c phn mm lu li trn mt file mdb (nh
dng file d liu ca Microsoft Access) nm trong th mc cha chng trnh.
Ngoi ra mt iu rt quan trng chnh l cc d liu v tn hiu in tim cng c
phn mm thc hin lu li trn cc file *.ECG vi tn file chnh l m lu tr.
Vic to ra file t nhng d liu nhn c t mch o c thc hin bng vic s dng m
hnh FSO (File System Object). Nhng file ny c lu tr trong th mc data
nm cng vi file chy phn mm. D liu t cc file ny d dng c truy xut v
tin hnh v li th in tim o c sau khi c yu cu (nhn vo nt XEM trn ca s
qun l d liu). 5.3. Thc hin m phng phn mm v nhn xt. Thc hin m phng
phn mm Sau khi hon thnh phn mm, em thc hin m phng Chng trnh bng
Virtual Serial Port Driver. Chng trnh ny cho php thit lp cc cng COM
o. Phn mm trn PC v trn PIC c a vo chng trnh m phng Proteus 7.2 kim
tra. Phn giao tip c thng qua kt ni COM o. Cng COM 2 t trn PC c ni
cho vi COM 3 trong chng trnh m phng thng qua phn mm Virtual Serial
Port Driver 6.9.
Thit k thit b o in tim mini 19
Hnh 5.4: S m hnh m phng trn Proteus Kt qu thu c: phn mm v ng c
tin hiu in tim khi c vi x l gi ti t chng trnh m phng Proteus. Phn
mm c kh nng qun l v lu tr d liu in tim theo ng nh thit k. nh gi nhn
xt v phn mm u im: Giao din n gin, d s dng cho cc i tng. C kh nng
thay i, iu chnh ng truyn cho hp vi thit b. To dng c mt h thng c s d
liu kh y rt hu ch cho lu tr v cc cng tc chun on bnh. Nhc im: Giao
din thc hin trn tool Teechart ca VB do ha cha c p. Phn mm cn s khai
nn cha c nhiu tnh nng phc v cc nhu cu chuyn bit khc nhau. 6. Kt lun
v mt s kt qu ca mch o in tim Mch vi x l chy c cc chc nng thit k:
giao tip LCD, RS232, phm, RTC
20 n Thit b o
Hnh 6.1: Kt qu test phn cng vi LCD v phm bm Mch tng t u vo khuch
i ng vi tn hiu hnh sin u vo. t vo b khuch i bng in p phn p chiu hnh
sin trn bin tr vi chnh 100K ta thu c in p xoay chiu 1.2sin( t+ )
(mV)
Hnh 6.2: Phn p in p xoay chiu 12V ly in p 1.2mV
Hnh 6.3: Tn hiu hnh sin qua b khuch i v lc ( c b offset)
Thit k thit b o in tim mini 21 Mch o cha c b phn lc ct tn s 50Hz
v vic tn s ny nm trong di thng ca cc b lc nn tn hiu ny c khuch i m
ko b kh. Do nh hng t nhiu (ly tn hiu mu mc milivolt) nn in p hnh
sin u ra khng c chun xc tuyt i. Tuy nhin vic tn hiu hnh sin c khuch
i chng t l mch khuch i hot ng. S liu thu c qua x l, thc t trc khi
quy i bin tn hiu hnh sin m ADC nhn c l ~1.1V (cha k n in p offset t
b khuch i lp). H s khuch i thc t o c l 1100/1.2=916.7 gn ng vi h s
khuch i tnh ton trn l thuyt (877). S sai khc ny l do vic linh kin c
sai s ln (do iu kin nn cha th dng cc linh kin dn vi chnh xc cao).
Tuy nhin do vn v cht lng mch in nn nhm cha th x l c nhiu trong qu
trnh o. Mt khc do cht lng linh kin nn cc b lc hot ng khng nh mun.
Biu hin vic xut hin cc thnh phn nhiu bc cao khi tin hnh gn in cc o
tn hiu in tim. Cc mc tiu ca ti t c tng i, tuy nhin vic o in tim vi
cht lng tt nht cha thc hin c. Do cn nhiu vn m hin ti nhm cha th gii
quyt nn nht nh s tip tc nghin cu trong thi gian sp ti. Nhng vn cn
ng li m cn tip tc gii quyt: Thc hin kim tra thit k mch cng, tnh ton
cc b lc cho u vo analog tn hiu in tim. Tip tc nghin cu chun ha tn
hiu, s dng cc thit b linh kin hin i v cht lng cao hn hon thin sn
phm. M rng thm mt kt ni chun USB bn cnh chun RS232. Xy dng mt chng
trnh kt ni TC/IP cho thit b. thun tin hn cho vic theo di v a ra cc
khuyn co kp thi cho cc bnh nhn phi thng xuyn di chuyn. Xy dng mt h
thng chuyn gia n gin c th t vn trc tip cho bnh nhn Vi cc mc tiu trn
trong tng lai chng em s c gng sm hon thnh. Nhm cung cp mt thit b
tin dng. hu ch ti cc tt c mi ngi vi nhu cu o kim tra sc khe thng
xuyn.
22 n Thit b o
Tng hp mt s ti liu tham kho:1. ti: NGHIN CU THIT K MY O TN HIU
IN TIM S DNG DSP
Nguyn Lan Hng, Phm Ngc Yn, Nguyn Quc Cng 2. ti: The Isolation
Mode Rejection Ratio in Bioelectric Amplifiers A.C. MettingVanRijn,
A. Peper, C. A. Grimbergen..
http://www.biosemi.com/publications/artikel5.htm 3. Project: ECG
Primer 1.0 - http://www.stm32circle.com/projects/project.php?id=31
4. Datasheet cc linh kin: + AD620AN:
http://www.datasheetcatalog.org/datasheet/analogdevices/105505445AD620_e.pdf
+ TL082CN:
http://www.datasheetcatalog.org/datasheet/stmicroelectronics/2300.pdf
+ OP07CP:
http://www.datasheetcatalog.org/datasheet/analogdevices/53280594OP07_a.pdf
+ KA78xx: http://www.kmk.com.hk/Manuals/7805.pdf + KA79xx:
http://www.datasheetcatalog.org/datasheets2/42/424907_1.pdf +
PIC16F877A:
http://ww1.microchip.com/downloads/en/DeviceDoc/39582b.pdf 5. Gio
trnh Visua Basic ca FPT 6. Gio trnh Microsoft Access 2000 ca Nguyn
Sn Hi 7. Gio trnh tin hc lp trnh trc quan ca Nguyn Trung Hoa 8.
Microsoft Access 2000 Bible Quick Start; Cary N.Prague, Michael
-R.I Ruin 9. Microsoft Access 2000 with VBA Advanced; Al Napier,
Phil Judd, H.Albert Napier, Philip J. Judd.
