Need help with my final year project...

[navarro_boyz]

Hi guys.

I am a final year student of Beng Electrical and Electronic.I am currently doing a project titled "heart rate measurement using fingertip" by Dogan Ibrahim and Kadri Buruncuk @ http://www.emo.org.tr/ekler/a568a2aa8c19a31_ek.pdf and i have modified the circuit and the programming based on my ideas.Therefore, I would like to ask your help in order to check whether there is any problem with my circuit diagram and also with my programming code since i have modified the project on my own.In the hardware side, it works fine but i could not simulate it on the proteus and i suspect that there might be a problem on the circuit part that i may have overlooked.If there is no problems,then only i can do the etching process.

The original circuit by Dogan Ibrahim and Kadri Buruncuk.

My modified circuit.

I added the buzzer on the pin 18 and the "abnormalities" led on the pin 17 of the pic16f784a.In addition,I also added the "on" indicator led with the +9V and the "reset push button" through the pin 4 of the pic16f84a.The programming also have been done according to the changes desired.

The original operation of the project...

BEGIN
Initialize program variables
Configure input-output ports
Display message “READY”
Wait until switch is pressed
Sum = 0
DO 3 times
Get count in 10 seconds
Count = 6 * Count
Sum = Sum + Count
ENDDO
Calculate the average, Rate = Sum / 3
Display the average on the LCD
END

My desired operation of the project...

BEGIN
Initialize program variables
Configure input-output ports
Display message “READY”
Display message "PRESS START"
Wait until switch is pressed
Sum = 0

DO 3 times
Get count in 10 seconds
Count = 6 * Count
Sum = Sum + Count
ENDDO
Calculate the average, Rate = Sum / 3

Normal heart rate
Display the average on the LCD
Beep once using buzzer

High or low heart rate
Display the average on the LCD
Beep three times using buzzer
Led blinking continuously

END

The rest of the information are attached together with this thread.
[url]http://www.mediafire.com/?v1suh1fzi19tqyu[/URL]

Note: For the proteus simulation, i have to use the opto-coupler because i could not find the IR diodes.

 

[(*steve*)]

It seems to me that you have not significantly changed the critical parts of the circuit, so I suggest that your device will (generally speaking) perform as per the original.

The issues that remain are essentially software related. I don't know if you're copying their software too (and modifying it slightly) or designing your own.

I would try to couple a (say) 1Hz signal to the input to assure myself that the device reads accurately.

I'm not quite sure about the 2Hz cutoff though. I'm sure the original designers determined that for some good reason, but since it corresponds to only a heartbeat of 120bpm, perhaps you might have some justification in increasing this (to at least 3Hz!)

'You won;t be able to model the behaviour of this circuit unless you modify it to add some source of input signal. The optocoupler you've shown is clearly meant to represent the finger clamp, but no program is going to be able to figure out that it needs to add a heartbeat there!

 

[Laplace]

My concern is with the component "U1". The original circuit shows two separate components, one IR LED and one phototransistor, whereas your circuit shows these as a single component U1 optocoupler. My question is how do you intend to attach U1 to a person's finger in order to sense the change in blood volume within the finger? Or is U1 not actually an optocoupler but rather just a representation for Figure 2 in the Dogan & Buruncuk original paper?