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Holter monitor - wireless ECG with ADS1292 and Bluetooth

vix3c
Intellectual 430 points
Other Parts Discussed in Thread: ADS1292R, ADS1292, ADS1293, ADS1292RECG-FE, CC2541, ADS1298

I am developing holter monitor which records ECG signals for at least 24 hours and then transmits measured data over Bluetooth to the Android phone where application displays visual graphs. I believe that ADS chips would suit the best for my case so I have already bought ADS1292R Demonstration Kit. However I recently came across the youtube video Wireless ECG demo with the ADS1293 where comment section lead me to Wireless Heart Monitor with Bluetooth Low Energy article. I was wondering what are the differences between the Demonstration Kit and the product in that project? Which one would you recommend more for my case? I have also seen a video of Heart Rate Monitor Chest Strap which is a very similar product to the one I would like to achive. What parts are used in that project, is it possible to get source codes, original design files etc.?

I was also wondering if there are any limitations and compatibility concerns for ECG cables/straps? I have seen in user's guide that a special ECG cable N26082011 should be used with ADS1292R demonstration kit. Would it also work with other 4-lead ECG cables with PB9 connector or is it neccessary to get that specific one? Where may I buy it?

The second part of the project is replacing TI's microcontroller with Arduino since it would suit better for my development needs. My idea was to bypass lines 16-22 (please see the image here) and connect it to Arduino microcontroller. Would that work or is the process more complex? What are the technical requirements for microcontroller to handle the signals from ADS1292?

Thank you very much for help in advance.

  • 0
    TI__Mastermind 38745 points

    Hey vix3c,

    Unfortunately I have to tell you that the ADS1292R Demonstration Kit is really an evaluation module for the ADS1292R which is the 24-bit ECG front end IC. We do not support the use of an EVM as an end product or in use as part of an end application. I will not be able to advise you in changing the hardware or software in that EVM to fit your project, but if you buy it you are certainly allowed to do with it what you want. Similarly, I can't advise on electrodes/cables since that implies it will be connected to a person. Let me specify what is available to you in relation to the ADS1292R demonstration kit:

    • A PDF version of the schematics near the end of the User's Guide. The original design was created on now defunct software. The original files do not exist.
    • Source code for the LabVIEW GUI, MSP430 firmware, and a Windows device driver all available upon request. However, this code is not "sample code" in that its purpose is not instructional. It may be hard to follow and it may not be ideal for end applications.

    The ADS1293 is a different ADC from the ADS1292R, though their target application is the same. The best way for you to see the differences would probably just be to look at each device's respective datasheet and compare features and performance. The Wireless Heart Rate Monitor with Bluetooth Low Energy is a TI Design rather than an EVM, so those design files should be available on the landing page for that design if you scroll down a little.

    I'm not sure that the other things you mentioned were anything more than internally created demos and never had the intention of publicly releasing them.

    Regards,

    Brian Pisani

  • 0 in reply to Brian Pisani
    Intellectual 430 points

    Dear Brian,

    thank you for prompt reply. Is evaluation module ADS1292R therefore only designed to use with the Windows software provided? Can it even measure real-world ECG signals e.g. from people? I understand that it was designed to use with simulator, but still, would that be technically possible? What is therefore even it's purpose if the provided software is defunct and there is no support for it? Could I create new firmware and moreover connect the borad to an Android device or is limited in the way that this would be impossible to realize?

    If I understand you correctly, Wireless Heart Rate Monitor with Bluetooth Low Energy is in fact designed to be used with persons in real-world and comes with a better support on TI community? Since you are most probably much more skilled and informed with before mentioned applications, what would be your recommendation for my case given the circumstances? As far as I see it, Wireless Heart Rate Monitor with Bluetooth Low Energy would make the development process noticeable smoother and would speed up the whole process since the hardware is already designed closer to my end application. In addition to the limited support of demonstration kit, would you recommend me to use it instead ADS1292RECG-FE for basis?

    Kind regards,

    Vix3c

  • 0 in reply to vix3c
    TI__Mastermind 38745 points
    Hey Vix3c,

    The reason TI is so careful about telling customers that they can use one of our "designs" in an end-equipment is that TI is really just a chip vendor and providing end-use designs to customers can potentially open TI up to liability for legal claims should a customer's application fail or, in the case of medical equipment, kill or injure someone.

    So this is the official line, and you are free to interpret it as you like: the ADS1292RECG-FE is an evaluation module designed for customers to evaluate functionality and performance for the ADS1292R which is an integrated medical front end IC. The EVM (as opposed to the chip) is to be used in a laboratory environment with a simulator. If you would like to design a system to monitor patients in a medical system using the ADS1292R, designing and testing that system is your responsibility, though you may certainly receive technical support from TI as you design our chip (not the EVM) into your system. You agree by purchasing the EVM that you will not use it in a way that is not intended and that if you do TI is not responsible for any resulting injuries, damages, etc. To answer your question in short, it may be possible to modify the design to make it do what you want, but you won't get any help from us in doing that.

    Now for the TI Design... TI Designs are reference designs and instructional technical examples of using TI integrated circuits in an application targeted sub-system. You are free to use the design files and any other documentation as a reference for your own design, but it should be clear that, again, TI bears no responsibility for the performance, functionality, or safety of your final design. TI can definitely answer questions about how that design functions or technical help on how to integrate it with additional pieces of your system.

    Regards,
    Brian Pisani
  • 0 in reply to Brian Pisani
    Intellectual 430 points

    Dear Brian,

    I understand that TI cannot be held responsible for the usage of EVM in applications outside the laboratory environment, but that is clearly stated in TOS so no legal claims can be made and I therefore do not see how would that reflect in lack of support. I thought that EVM is designed especially for testing and developing purposes, so customers would be able to get accustomed to ADS chips more thoroughly which would eventually help them with designing their own IC. Now I have paid 100+ $ for EVM which comes with a defunct software and no real possibilities to test and learn anything useful from it at all. Since I do not own ECG tester, I cannot even test it out, although I would certainly do it on my responsibility and completely agree on that term.

    Nevertheless, unless you have perhaps any better propositions, I see no other logical way at that point but to use Wireless Heart Rate Monitor with Bluetooth Low Energy and modify/implement it into my application. Before I rush with the order of material, please let me know if this IC is technically suitable to work with Android devices as well (of course with Android app development)? Would it be also possible to record ECG readings for 24 hours, store them on IC and then transfer them over Bluetooth to an Android device (Holter monitor functionality basically) or would that require a hardware modification?

    Where may I buy suitable electrodes?

    Could you also give me any hint on how could I modify IC to work with Arduino microcontroller?

    Thanks for help & best regards.

  • 0 in reply to vix3c
    TI__Mastermind 38745 points

    Hey vix3c,

    To which integrated circuit are you referring in the Wireless Heart Rate Monitor with Bluetooth Low Energy TI Design? There is the ADS1293 which is an ADC and the CC2541 device which is the Bluetooth chip. I am not totally sure what the CC2541 device is capable of. You can either read the datasheet for that device thoroughly or jump over the Bluetooth Low Energy e2e forum and ask about that device there. From glancing at the design guide, the CC2541 has a 8 KB of RAM on chip which I'm guessing will not allow for 24 hours worth of ECG data storage. I believe instead the goal is to transmit the data in near real-time to a host controller for processing. You could potentially create a design where the data is instead stored in some sort of external memory on the board until it is retrieved later.

    There looks to be an iOS app that they have developed along with this design (source code included), so it seems ostensible to create an Android version. The Bluetooth Low Energy forum is a good place to start with questions about that part of the design. This forum is dedicated to data converter discussions.

    Unfortunately, I do not know where to buy electrodes.

    For your last question, which integrated circuit are you talking about? Are you instead talking about the EVM printed circuit board? If so, we do not support modification help. The schematics are available, though, and the ADS1292 communicates via a SPI compatible interface. I would recommend reading the datasheet for the ADS1292 thoroughly.

    Best Regards,

    Brian Pisani

  • 0 in reply to Brian Pisani
    Intellectual 430 points

    Dear Brian,

    I will check at Bluetooth Low Energy forum for the best way to store ECG readings. Could you give any rough guess on how much memory would I need to store all the readings for 24 hours?

    Who may I ask about the electrodes, perhaps the authors of Wireless Heart Rate Monitor with Bluetooth Low Energy TI Design would be the right address? How may I contact them?

    I was referring to the Wireless Heart Rate Monitor with Bluetooth Low Energy TI Design. Since ADS1293 does not support data storing, that part would have to be done by a microcontroller. In that case, I could replace CC2541 with Arduino or any other suitable microcontrollers. Could you help me out with modification of the circuit?

    Also I could not find anywhere pros/cons, or in other words a comparison between using different number of channels. What difference would it make to use ADS1292, ADS1293 or e.g. ADS1298?

    Best regards

  • 0 in reply to vix3c
    TI__Mastermind 38745 points
    Hey vix3c,

    With just a rough estimate, the ADS1293 is a 3 channel device with 24 bit data which means there is a minimum of 9 bytes per conversion. The lowest sample rate is 25 SPS so in 24 hours you would collect 24 hrs x 60 min/hr x 60 s/min x 25 samples/s = 2.16 million samples which 2.16 million samples x 9 bytes per sample puts you at nearly 20 MB.

    I doubt that anyone at TI would be able to help you with electrodes. We are a chip manufacturer and electrodes are more in the realm of medical equipment manufacturers. You may certainly ask on the forum, though. That may be the best way to contact the authors.

    You can find detailed information about interfacing with the ADS1293 on that device's datasheet, but if you have remaining questions, you can post them on this forum. Microcontroller questions should be directed to another forum. I can tell you now, though, that you will not get technical help from TI replacing one of our chips with one of our competitor's :-)

    The question is simply how many conversion channels does your application require? How many ECG electrodes are you trying to connect?

    Regards,
    Brian Pisani
  • 0 in reply to Brian Pisani
    Prodigy 60 points
    Hi, Brian,


    Could you send me the mentioned codes?

    "Source code for the LabVIEW GUI, MSP430 firmware, and a Windows device driver all available upon request."

    Thanks in advance,
  • 0 in reply to Humberto Neto
    TI__Mastermind 38745 points
    Hello Humberto,

    May I send it to your email address associated with your myTI account? Is there a different one you would prefer?

    Brian
  • 0 in reply to Brian Pisani
    Prodigy 60 points
    Hi, Brian,

    You may send it to my myTI account associated email.

    Thanks in advance,
  • 0 in reply to Brian Pisani
    Intellectual 370 points
    Hello Brian,

    I developed a quite similar PCB, based on TIDA00096 (www.ti.com/.../tidu195a.pdf). It's a holter application, however the electronic goals of the engineering team had changed and this project was been stoped years ago.

    Now, I'm restarting the funcionality of my holter PCB for my PhD. I've verified the ECG data via BLE using the USB dongle (Snifer and BLEtool). Nevertheless, I would like to see a ECG diagram/wave form. I try to obtain the iOS APP that Texas provided to users some time ago, but It's not avaliable. As you can understand, this App or similar it could be really useful to check the hardware funcionality quickly. This can save along time of App development on prototyping stage.

    Could you recomend some avaliable APP to check and veiw directly the ECG wave form? Is It possible find a way in order to reach direct goals of my PhD and not spend time on a development for custom APP ?

    Thanks for your time.
    I'm looking forward hering about your reply
  • 0 in reply to Robert Camos Vidal
    TI__Mastermind 38745 points
    Hello Robert,

    Unfortunately if it is not available online, it is because TI has decided to discontinue its distribution. I apologize for the inconvenience this will cause. TI would certainly be willing to help you understand any TI devices you are using and solve any issues you encounter here on the e2e forum.

    Regards,
    Brian Pisani