Heart Beat Counter Circuit

[[email protected]]

Hi All,

I am in DESPERATE need of some advice here. I am working on a project
for my basic electronics design class. Here is what I need to do...

Design a heartrate counter that
-uses 2 electrodes as the signal source, removes high frequency noise
- counts pulses for 15 seconds every minute
- displays the per minute heart rate for 45 seconds on a three-digit
digital display
- reset the count every 60 seconds and restart the counter

So far, I've got a heart rate pulse going into the counter for 15
seconds every minute. For the other 45 seconds of the minute, nothing
feeds into the counter. (This was done using filters, a comparator, a
15 second astable multivibrator, 2 bit counter, nor gate, and an and
gate)

So right now I need to figure out how to:
- reset the counter every 60 seconds
- connect the counter up to a three-digit digital display

I would be SO GREATFUL if someone could help me out with the counter
reset and display portion of this-

Thanks!
Rachel

 

[Jan Panteltje]

Hi All,

I am in DESPERATE need of some advice here. I am working on a project
for my basic electronics design class. Here is what I need to do...

Design a heartrate counter that
-uses 2 electrodes as the signal source, removes high frequency noise
- counts pulses for 15 seconds every minute
- displays the per minute heart rate for 45 seconds on a three-digit
digital display
- reset the count every 60 seconds and restart the counter

So far, I've got a heart rate pulse going into the counter for 15
seconds every minute. For the other 45 seconds of the minute, nothing
feeds into the counter. (This was done using filters, a comparator, a
15 second astable multivibrator, 2 bit counter, nor gate, and an and
gate)

So right now I need to figure out how to:
- reset the counter every 60 seconds
- connect the counter up to a three-digit digital display

I would be SO GREATFUL if someone could help me out with the counter
reset and display portion of this-

Thanks!
Rachel

Use Microchip PIC microcontroller, you will have to proram it, learn ASM.
(or other micro processor) every other way probably needs more hardware.

 

[[email protected]]

Oops- forgot to mention that its all in hardware- we're not allowed to
use software for this project!

 

[Winston]

Hi All,
(...)

So right now I need to figure out how to:
- reset the counter every 60 seconds

Is there room for a 3 bit counter on your board? You could increment it
during each 15 second interval and it would go to 0x100 at the end of
60 seconds. When the MSB goes high, reset both counters.

- connect the counter up to a three-digit digital display

Look up 'seven segment decoder'.

--Winston

 

[Leonard Lollobol]

Oops- forgot to mention that its all in hardware- we're not allowed to
use software for this project!

Ok, homework, counter:

3 seven segment displays.
3 BCD to seven segment decoders / drivers
3 quad latches
3 74HC[T]90 decade counters with BCD output in series to count pulses.
1 555 timer running at some high frequency
1 binary divider so you get the last Q output high after 60 seconds,
this then triggers some one-shots that 1) latch the decade counter output,
2) reset the decade counters so the display is updated.
That was the part you did not know?
For better accuracy you could use a crystal (not a 555 timer).
All is available in 74HC range for 5V.

 

[martin griffith]

On 10 Dec 2006 09:28:02 -0800, in sci.electronics.design

Hi All,

I am in DESPERATE need of some advice here. I am working on a project
for my basic electronics design class. Here is what I need to do...

Design a heartrate counter that
-uses 2 electrodes as the signal source, removes high frequency noise
- counts pulses for 15 seconds every minute
- displays the per minute heart rate for 45 seconds on a three-digit
digital display
- reset the count every 60 seconds and restart the counter

So far, I've got a heart rate pulse going into the counter for 15
seconds every minute. For the other 45 seconds of the minute, nothing
feeds into the counter. (This was done using filters, a comparator, a
15 second astable multivibrator, 2 bit counter, nor gate, and an and
gate)

So right now I need to figure out how to:
- reset the counter every 60 seconds
- connect the counter up to a three-digit digital display

I would be SO GREATFUL if someone could help me out with the counter
reset and display portion of this-

Thanks!
Rachel

you didnt spec accuracy
rough idea
555, at a 15 sec count
binary up counter 74 or CD4000 series
74hc138 will decode the lowest 3 lines of the counter into induvidual
lines

Thats a start, what would you do next?


martin

 

[linnix]

Oops- forgot to mention that its all in hardware- we're not allowed to
use software for this project!

Ok, homework, counter:

3 seven segment displays.
Yes.

3 BCD to seven segment decoders / drivers
3 quad latches
3 74HC[T]90 decade counters with BCD output in series to count pulses.

1 CPLD.

1 555 timer running at some high frequency
Yes.

1 binary divider so you get the last Q output high after 60 seconds,

included in CPLD.

 

[[email protected]]

I have a few silly questions- I'm not too familar with all of this
stuff soo....

-are you saying I should use three decade counters together? how does
one set them up to count together?
- what is a binary divider? What is "Q" output? Would I set the "Q"
output to the reset terminal of the coutners to that they reset every
60 seconds?
- what are quad latches?

Sorry if I'm painfully novice at this! I'm just trying to imagine the
actual set up of this thing on our board and am not sure what some of
these components are!

Thanks again,
Rachel

1 binary divider so you get the last Q output high after 60 seconds,
this then triggers some one-shots that 1) latch the decade counter output,
2) reset the decade counters so the display is updated.

Oops- forgot to mention that its all in hardware- we're not allowed to
use software for this project!

Ok, homework, counter:

3 seven segment displays.
3 BCD to seven segment decoders / drivers
3 quad latches
3 74HC[T]90 decade counters with BCD output in series to count pulses.
1 555 timer running at some high frequency
1 binary divider so you get the last Q output high after 60 seconds,
this then triggers some one-shots that 1) latch the decade counter output,
2) reset the decade counters so the display is updated.
That was the part you did not know?
For better accuracy you could use a crystal (not a 555 timer).
All is available in 74HC range for 5V.

 

[[email protected]]

But how exactly does one reset the counters? Is it just a matter of
sending that pulse every 60 seconds to a reset terminal? Also, do you
have any suggestions for specific counters to use?

Thanks again!

 

[John Fields]

Hi All,

I am in DESPERATE need of some advice here. I am working on a project
for my basic electronics design class. Here is what I need to do...

Design a heartrate counter that
-uses 2 electrodes as the signal source, removes high frequency noise
- counts pulses for 15 seconds every minute
- displays the per minute heart rate for 45 seconds on a three-digit
digital display
- reset the count every 60 seconds and restart the counter

So far, I've got a heart rate pulse going into the counter for 15
seconds every minute. For the other 45 seconds of the minute, nothing
feeds into the counter. (This was done using filters, a comparator, a
15 second astable multivibrator, 2 bit counter, nor gate, and an and
gate)

So right now I need to figure out how to:
- reset the counter every 60 seconds
- connect the counter up to a three-digit digital display

I would be SO GREATFUL if someone could help me out with the counter
reset and display portion of this-

---
I'll be happy to help you, but I think you have a problem with that
15 second measurement in that you'll have to multiply it by four to
get the one minute rate and you'll lose some data in the units or
possibly even tens of beats per minute doing it that way. If the
design rules aren't fixed, I suggest that you count beats for a full
minute, then latch and display that data at the same time that you
reset the counter and start another count cycle. That way you'll
have new data coming in every minute and the counter will always be
working in the background. If you're interested, I can post a
schematic to alt.binaries.schematics.electronic, or email you one
since you can't access abse from Google.

 

[[email protected]]

That would be awesome! The problem is that we really do have to count
for only 15 seconds and then multiply by 4 to get the beats per minute.
My teacher suggested doing this by moving some of the wires over two
places(?) in the counter because that would multiply everything by
four. I'm not sure I truly understood his hint. I would love to post
the 2 schematics I have right now so you could see what I'm working on-
do you know where/how I could post these and would you even be willing
to take a look at them?

Thanks!

Rachel

 

[John Fields]

That would be awesome! The problem is that we really do have to count
for only 15 seconds and then multiply by 4 to get the beats per minute.
My teacher suggested doing this by moving some of the wires over two
places(?) in the counter because that would multiply everything by
four. I'm not sure I truly understood his hint. I would love to post
the 2 schematics I have right now so you could see what I'm working on-
do you know where/how I could post these and would you even be willing
to take a look at them?

---
Sure. Post them to a web page somewhere or, if you can't do that,
email them to me and I'll post them to abse so everybody can play.

That multiply-by-four is going to make things nasty, and there's no
need for it.

Here's what your instructor was talking about:

Lets say you measure beats for 15 seconds using an 8-bit binary
counter and you get:

0000 1111

which converts to decimal 15.

Shift the pattern one bit to the left:

0001 1110

and that becomes decimal 30.

Shift it once more and it becomes:

0011 1100

which is decimal 60, but it's been done in binary and it'll have to
be converted to Binary Coded Decimal (BCD) in order to be displayed
using easily available parts.

If it's your instructor's intention to have you learn to do binary
multiplication as well as binary-to-BCD conversion then, for your
application, doing the conversion would probably be easiest by
counting the beats for 15 seconds using a binary up/down counter in
'up' mode, wiring the Q outputs to the D inputs so that Q0 goes to
D2, Q1 goes to D3, Q2 goes to D4, and so on. Then, when the 15
second accumulation period ends, do a load. That will load a number
4 times greater than what the counter counted, back into itself.

Also, when the 15 second period ends, clear a BCD counter.

Now, reverse the counting direction of the binary counter and use a
convenient clock to simultaneously clock both the binary and the BCD
counter. Make it so that when the binary count gets to zero the Q
outputs of the BCD counter are loaded into BCD-to-seven-segment
decoder-drivers, and that'll cause the displays to show four times
the number of beats picked up in the previous 15 seconds.

The conversion and display can be done in microseconds so, unless
the one-reading-per-minute spec is cast in stone, for extra credit
you might want to think about doing more than just one
measure-convert-display cycle per minute.

 

[[email protected]]

Cool. I just sent you an email with my current-state schematics. Thanks
for the description of the multiply by 4 hint- I totally get it now. I
also think that I understand theoretically how this could work now, but
still dont get how the BDC and the counter would actually fit into the
circuit? Just to clarify, is the counter just a series of JK flip
flops? Hmm...

R.

 

[Joerg]

But how exactly does one reset the counters? Is it just a matter of
sending that pulse every 60 seconds to a reset terminal? Also, do you
have any suggestions for specific counters to use?

Please post at the bottom of messages, not at the top. Makes it easier
to read.

You can reset counters via a pulse on the reset line. Make sure to use
counters with unconditional reset, not some where the reset will only
happen upon the next clock.

 

[Luhan]

Cool. I just sent you an email with my current-state schematics. Thanks
for the description of the multiply by 4 hint- I totally get it now. I
also think that I understand theoretically how this could work now, but
still dont get how the BDC and the counter would actually fit into the
circuit? Just to clarify, is the counter just a series of JK flip
flops? Hmm...

What school are you attending where they teach you how to do outdated
designs??? Just glad the teacher didn't insist on you doing it all
with tubes and relays! Really, get with it dude and learn why we do
all this with microcontrollers today.

Luhan

 

[[email protected]]

haha, I KNOW! Not to mention, the teacher gave us this project just
recently and expects us to complete it all during exam week!

Rachel

 

[jasen]

Hi All,

I am in DESPERATE need of some advice here. I am working on a project
for my basic electronics design class. Here is what I need to do...

Design a heartrate counter that
-uses 2 electrodes as the signal source, removes high frequency noise
- counts pulses for 15 seconds every minute
- displays the per minute heart rate for 45 seconds on a three-digit
digital display
- reset the count every 60 seconds and restart the counter

So far, I've got a heart rate pulse going into the counter for 15
seconds every minute. For the other 45 seconds of the minute, nothing
feeds into the counter. (This was done using filters, a comparator, a
15 second astable multivibrator, 2 bit counter, nor gate, and an and
gate)

So right now I need to figure out how to:
- reset the counter every 60 seconds
- connect the counter up to a three-digit digital display

I would be SO GREATFUL if someone could help me out with the counter
reset and display portion of this-

I note you're not using a microcontroller, I'll assume there's a reason
for that.

some hints, look into using counters that can drive the display directly,
or maybe BCD counters and BCD-TO-7segent converter chips.

at the end of the 45 second period you need to send a reset pulse to the
counters. a R-C high-pass filter could be one way to do that.

Bye.
Jasen

 

[jasen]

I have a few silly questions- I'm not too familar with all of this
stuff soo....

-are you saying I should use three decade counters together? how does
one set them up to count together?

have you looked at the data sheet for these parts?

- what is a binary divider?

divide-by-two counter, eg: flip-flop with D wired to Q-bar

What is "Q" output?

non-inverting

Would I set the "Q"

output to the reset terminal of the coutners to that they reset every
60 seconds?
- what are quad latches?

google for a datasheet.


Bye.
Jasen

 

[jasen]

What school are you attending where they teach you how to do outdated
designs??? Just glad the teacher didn't insist on you doing it all
with tubes and relays! Really, get with it dude and learn why we do
all this with microcontrollers today.

Chill! slow rate logic is good for teaching, you can debug it with a bunch
of LEDs.

Sure a micro coild solve this task with more accuracy and less hardware, but it
doesn't teach clocks, gates, counters, and latches.

Bye.
Jasen

 

[Luhan]

haha, I KNOW! Not to mention, the teacher gave us this project just
recently and expects us to complete it all during exam week!

They got you using hardware logic to do heart monitoring while I'm
using micros to do a yoyo.

http://members.cox.net/berniekm/yoyo.html

Luhan