Thanks for the update, Ed! Congrats on the progress you've made.
I was going to warn you about the 2.5 volt signal (since the DS2423 needs more) but figured you'd know that. Sorry I wasn't able to provide that help.
When I ran the sensor directly into an input port on the BS2, I did not see a double spike on the pulse. Could this be something about how you're using the DS2423? Or is your chestband device one that is encoded to reduce cross-talk from other nearby chestbands? I don't know how they do their encoding.
Once again, congrats and thanks for keeping me in the loop on your progress. I'm pretty tied up with work right now, so it'll be a while before I can get back to it!
All day i have been busy with my setup. I integrated a transistor to·convert and invert the 2,5V to 5V pulses. It was counting quite good,·and i even added a small piezo buzzer to make the heart rate audible. But then disaster struck. It seemed to have died on me. I suspected that i blew the sensor for maybe pulling too big of a current with the piezo. So i connected my second HR receiver (and had to cut the cord), but that didn't work either. Both sensors gave spontanious and irretic pulses at random interval. I checked the circuit like a million times, but couldn't find a fault.·Then, for some reason i connected one sensor when it was not fixed to the PCB, and it started to work again. So i swapped both sensors and the original sensor worked right away, but only when it was not fixed to the PCB. When i tied it to the PCB, it stopped working again. It came out that my GPS receiver is jamming the 5KHz signal, rendering it useless in the process. When i pulled the connector on the GPS receiver, the HR sensor worked, even when tied to the PCB. So another lesson learned: Beware, neighbouring signals on the same PCB will interfere with the HR sensors. That leaves me with quite a big problem. I have no place else to put the sensor. (during the edit of this post, it just struck me that the GPS operates at 4,8Kbaud and the HR receiver receives at ... 5KHz... that's too close to be a coïncedence)...
Secondly, i can confirm that my first HR transmitter emitted more pulses due to coding. I tested a second (cheaper) transmitter, and it transmits only single pulses. So the theory of "pulse and whobble" from the EKG is out the window. Oh well...
I now have to shield my HR receiver from the GPS signals somehow and i have a working unit. Include temperature and GPS info, store it to USB stick and the project is done.
Ed.
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A horse is a horse, of course of course...
Sorry to hear about the setback in your design. Cumbersome as it is, maybe you can attach the sensor to the transmitter and then wrap the whole thing in tin-foil?
I guess I'm glad that the double pulses were because you were using a coded transmitter. I had wondered what the signal from a coded HR transmitter looks like!
I'm still just too busy to have the time to work on the project. Shortly, my RTC (w/ hundredths of second resolution) will arrive in the mail at which point I'll try to dig into reading it. I've got to learn a bit of BCD math so I can determine the elapsed time in seconds.
Could you post your circuit and code sometime?
So my steps are 1) Get the RTC working. 2) use the DS2423 counter like you are. And 3) I want to hook up an LCD panel and graph my heartbeat over time. Some of the treadmills do this (they have built in Polar sensors). It's quite cool to see the peaks and valleys as I do wind sprints!
Comments
I was going to warn you about the 2.5 volt signal (since the DS2423 needs more) but figured you'd know that. Sorry I wasn't able to provide that help.
When I ran the sensor directly into an input port on the BS2, I did not see a double spike on the pulse. Could this be something about how you're using the DS2423? Or is your chestband device one that is encoded to reduce cross-talk from other nearby chestbands? I don't know how they do their encoding.
Once again, congrats and thanks for keeping me in the loop on your progress. I'm pretty tied up with work right now, so it'll be a while before I can get back to it!
All day i have been busy with my setup. I integrated a transistor to·convert and invert the 2,5V to 5V pulses. It was counting quite good,·and i even added a small piezo buzzer to make the heart rate audible. But then disaster struck. It seemed to have died on me. I suspected that i blew the sensor for maybe pulling too big of a current with the piezo. So i connected my second HR receiver (and had to cut the cord), but that didn't work either. Both sensors gave spontanious and irretic pulses at random interval. I checked the circuit like a million times, but couldn't find a fault.·Then, for some reason i connected one sensor when it was not fixed to the PCB, and it started to work again. So i swapped both sensors and the original sensor worked right away, but only when it was not fixed to the PCB. When i tied it to the PCB, it stopped working again. It came out that my GPS receiver is jamming the 5KHz signal, rendering it useless in the process. When i pulled the connector on the GPS receiver, the HR sensor worked, even when tied to the PCB. So another lesson learned: Beware, neighbouring signals on the same PCB will interfere with the HR sensors. That leaves me with quite a big problem. I have no place else to put the sensor. (during the edit of this post, it just struck me that the GPS operates at 4,8Kbaud and the HR receiver receives at ... 5KHz... that's too close to be a coïncedence)...
Secondly, i can confirm that my first HR transmitter emitted more pulses due to coding. I tested a second (cheaper) transmitter, and it transmits only single pulses. So the theory of "pulse and whobble" from the EKG is out the window. Oh well...
I now have to shield my HR receiver from the GPS signals somehow and i have a working unit. Include temperature and GPS info, store it to USB stick and the project is done.
Ed.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
A horse is a horse, of course of course...
Post Edited (Mr.Ed) : 5/3/2007 1:35:02 AM GMT
Sorry to hear about the setback in your design. Cumbersome as it is, maybe you can attach the sensor to the transmitter and then wrap the whole thing in tin-foil?
I guess I'm glad that the double pulses were because you were using a coded transmitter. I had wondered what the signal from a coded HR transmitter looks like!
I'm still just too busy to have the time to work on the project. Shortly, my RTC (w/ hundredths of second resolution) will arrive in the mail at which point I'll try to dig into reading it. I've got to learn a bit of BCD math so I can determine the elapsed time in seconds.
Could you post your circuit and code sometime?
So my steps are 1) Get the RTC working. 2) use the DS2423 counter like you are. And 3) I want to hook up an LCD panel and graph my heartbeat over time. Some of the treadmills do this (they have built in Polar sensors). It's quite cool to see the peaks and valleys as I do wind sprints!
Tom
In case you're still subscribed to this thread, I wanted to pass on a wonderful link: www.emesystems.com/BS2speed.htm
The "timer loop" topic about 3/4 down this page has some very simple code for timing. Good reading for the kind of project we've discussed.
How's your project coming?