BLOOD PRESSURE MONITOR

Hi all i am working on a project and i would like your help here is theme

To perform a measurement, we use a method called “oscillometric”. The air will be pumped into the cuff to be around 20 mmHg above average systolic pressure (about 120 mmHg for an average). After that the air will be slowly released from the cuff causing the pressure in the cuff to decrease. As the cuff is slowly deflated, we will be measuring the tiny oscillation in the air pressure of the arm cuff. The systolic pressure will be the pressure at which the pulsation starts to occur. We will use the MCU to detect the point at which this oscillation happens and then record the pressure in the cuff. Then the pressure in the cuff will decrease further. The diastolic pressure will be taken at the point in which the oscillation starts to disappear.

So far i have only developed softeware in c just interfacing ADC 0831.
so please help he in making amplifier for transducer.Ic AD620 and OPA2277 are not available in Pakistan can any 1 help me replacing following ckt with LM324

PLEASE DO NOT CREATE MULTIPLE THREADS!

I want to know that is it possiable to implement following using MC51 in c.

continusly check for voltage from ADC2 if it is greater than 4v then save the value from ADC1??

yes thats possible.

in C you get what you write. thats the reason C became so popular in embedded.

What logic is required I mean algo

@afnan,

so please help he in making amplifier for transducer.Ic AD620 and OPA2277 are not available in Pakistan can any 1 help me replacing following ckt with LM324

ur ckt diagram suggests that the AD620 is a instrumentation amplifier so to replace it by a lm324, u will have to rig up an instrumentation amplifier using three op-amps from a single package of lm324. As far as the OPA2277 is concerned, u can try replacing them directly with the individual op-amps of the lm324. I used the term 'try' because each op-amps have their on unique characteristics and the OP series are generally high performance OP-amps. So simply replacing them with a general purpose op-amp like 324 will have some trade-offs. U will have to check the output practically to know the difference.

What logic is required I mean algo

ur diagram suggests u are outputting an A.C. voltage to the ADC0. Can u clarify what type of waveform ( sine/pulse/square) appears there?.any particular reason to output a second order differential of the input?

its needed like this.we have to measure ossillations .going further when cuff has enough pressure that no blood flows through arm there would b no oscillations but when pressure is slowlly decreased a time comes when oscilation began to appear and grow when they reach their maximum pek lets say max amplitude (4v we set ). we measure dc pressure from ADC1.
type of wave expected are shown in PICTURE

well you mean you have to measure voltage of signal too at the same time. you might need a faster ADC for faster conversions. what is maximum frequency of the i/p signal?

Sorry i didnt understand i/p signal.Well i am using MC51 and serial adc ADC0831 and pressure sensor SCX15dn.And here is the web from where i am translating it from mega32 to mc51.

http://www.people.cornell.edu/pages/ws62/

i didnt mean to measure voltages at same time program remains in function which measures AC signals if they rise above 4v then go to function that records pressure.this is to b achived by two ADC.so we dont have to measure Pressure aswell as AC signals.

from the application ad the details related on the link provided, i presume the frequency of the oscillations is equal to the pulse rate which is around 70 ~ 80 bpm for a heathy soul.
So, u can just output it to ur ADC and sample the signal for every small interval of time and check the amplitude . As the frequency is very low ( ~1~2 Hz) , u can safely read the samples using a conventional 8051.


P.S. If u read the article in the link, u will get a fair explaination on deciding the sampling rate.