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Hi Willy_5,Thank you for visiting my project. Both circuits described in it are very simple, thus the layout of elements shown in images is purely intuitive. I took small boards purchased at RadioShack (R.I.P.), cut them into even smaller fragments, then placed and soldered the socket for 555 timer first. Next, I've connected discrete elements to it in the order of smallest (resistors) to largest (electrolytic capacitors). I had to solder a couple of wires, as well, and that was it.For more complicated circuits you may want to use an advanced software to lace elements for you (e.g., Eagle), or simpler software which recommends placement which you can later modify by drag-and-drop (e.g., Fritzing).Good luck!

Boards of Feather fly together, hence I don't see why your M0 Express would wire any differently than my M0 Adalogger (although my project is over 3 years old, so you have to verify it with Adafruit).Now, by "the code" you refer to Jiri's code? He does offer the main program heartRate.ino but without the necessary header files and libraries. I admit, I did not have time to read his Instructable in detail, so help me here: where did you get the missing code components?

No, this is not what I wrote in my most recent suggestions. To help you I have to see oscilloscope traces of signals on pins 2,3, and 7 _with_ motherboard connected. Without these you are on your own.

First, read and understand pages 12 and 13 of the MP3394 datasheet. Next, use an oscilloscope (borrow one if necessary) to measure signals the motherboard sends to both pins 2 and 3 when LEDs are turned on. Also, measure signal generated on pin 7. In addition, measure the voltage on pin 15 of MP3394 - does it use 5V or 3.3V logic?Send me images from the oscilloscope and the voltage on pin 15.

Yeah, you have determined the CN861 - LED connection, but you just "forgot" to mention it to me. If you send me all the relevant information at once, then you would not waste 11 days of Q&A to get answers, would you?Yes, voltage regulator would do the job of supplying 3.3V, but in my humble opinion it is an overkill. Simple voltage divider will suffice.

Ah, finally, I have enough information. It seems you are focusing on a wrong connector. It's not C701 that is important to your purpose, but CN861. Pins 8, 9, 10, 11 of MP3394 connect there and this connector is where all the LED cathodes should connect to. Are there 4 separate LED strings?Now, the remaining problem is the common LED anode. Obviously, it should come from the same voltage source that powers pin 15 of the MP3394, but it should come _after_ the cathode of D801! I guess, this voltage source comes out of the two middle pins of CN861 - but you have to precisely track it!Thus, the connection of LED strips is solved, but I can guess that without motherboard MP3394 will be disabled. Therefore, you have to supply 3V on _both_ pins 2 and 3 (i.e., the green and white wires of CN701).…

Ah, finally, I have enough information. It seems you are focusing on a wrong connector. It's not C701 that is important to your purpose, but CN861. Pins 8, 9, 10, 11 of MP3394 connect there and this connector is where all the LED cathodes should connect to. Are there 4 separate LED strings?Now, the remaining problem is the common LED anode. Obviously, it should come from the same voltage source that powers pin 15 of the MP3394, but it should come _after_ the cathode of D801! I guess, this voltage source comes out of the two middle pins of CN861 - but you have to precisely track it!Thus, the connection of LED strips is solved, but I can guess that without motherboard MP3394 will be disabled. Therefore, you have to supply 3V on _both_ pins 2 and 3 (i.e., the green and white wires of CN701). You can rig it as a simple voltage divider using one of the 5V wires (red or orange) as the voltage source. Make sure to use high value resistors for this divider. Now, I am assuming that pin 3, DBRT, expects a simple DC signal. Well, it may very well expect a PWM signal. This depends on the Dimming Control Mode - consult pages 12 and 13 of the MP3394 datasheet. It's hard to tell, since pin BOSC has both resistor and capacitor connected to it. The surest way to check it is with an oscilloscope while the motherboard is still connected. If it's PWM, then you may want to desolder the BOSC resistor and, perhaps, solder a proper capacitor (see page 13).

Sorry, I forgot to add that the DBRT pin expects no more than 1.2 V in the DC Input mode!

I see, the answers help a lot. Two more questions:1) Is MP3394 controller located on the motherboard?2) If I understand you correctly, you want to eliminate motherboard and power the LED strip directly from the power supply, is this correct?

Finally, you provide a useful connection diagram. Would you mind answering at least some of my questions? Like: 1) How do you turn the backlight LEDs now?2) What is connected to the BOSC pin (either 7, or 9, depending on the specific package of MP3394)?3) What is the type/model of your monitor?And yes, please do post _clear_ pictures of the board containing MP3394.

Here is the diagram

Hmmm... Every monitor I know of has an on/off switch. Why can't you use it? Is it because you have removed it along with motherboard? You have measured voltages in stand-by state as well as in the "on" state, hence you had to have some method of turning it on, right? How did you do that? Well, you wrote that Green wire is connected to the Enable pin of MP3394. Looks like this is the place where you can insert your bipolar switch: in one position it will deliver 3V to this pin, in the other position it will connect the pin to the ground.

I guess, your LEDs do light up and all you want is the dimming control, right? I am glad you mentioned MP3394, since it can provide LED dimming control. First, download its datasheet: https://www.monolithicpower.com/en/mp3394.html. You will see from the pin description that DBRT (pin 3) controls dimming. On page 9 of the datasheet you'll see there are two modes of dimming control: either PWM, or DC signal. You have to find out which mode your monitor uses and hack it accordingly.This page offers some useful info, as well: https://www.petervis.com/electronics%20guides/17ips20/mps3394s.html

What kind if monitor do you have? Can you send me its schematics?

It sounds like the well known problem with some cheap clones that have IR and RED channels swapped:https://github.com/aromring/MAX30102_by_RF/issues/13#issue-601473302

No, I haven't. It won't work on the wrist because of motion artifacts.

Yes, algorithm_by_RF.h uses defines that are different from yours, so start your debugging from there.Raivis Strogonovs' approach is interesting and well explained, but it's very different from mine.The FlexiPlot you have attached (thank you) has period of 0.96-0.97 s between peaks. Hence, it corresponds to an approximate HR = 62 bpm. No such HR is reported in the Serial Monitor capture, your second image, thus I am assuming FlexiPlot does not represent raw data for any of these outputs.

First, I don't think adding an INT wire is such a big deal, but maybe your ESP32 board does not have enough digital pins? Anyway, I took a look at the role of INT signal in my code (https://github.com/aromring/MAX30102_by_RF/blob/master/RD117_ARDUINO.ino) - it's only use is detection of the new data availability in the main signal loop:while(digitalRead(oxiInt)==1); //wait until the interrupt pin assertsThe analogous loop in SparkFun library (https://github.com/sparkfun/SparkFun_MAX3010x_Sensor_Library/blob/master/examples/Example8_SPO2/Example8_SPO2.ino) features the following calls instead: while (particleSensor.available() == false) //do we have new data? particleSensor.check(); //Check the sensor for new dataSee the enclosed images. Thus, it's rather obvious what to do. I mig…

First, I don't think adding an INT wire is such a big deal, but maybe your ESP32 board does not have enough digital pins? Anyway, I took a look at the role of INT signal in my code (https://github.com/aromring/MAX30102_by_RF/blob/master/RD117_ARDUINO.ino) - it's only use is detection of the new data availability in the main signal loop:while(digitalRead(oxiInt)==1); //wait until the interrupt pin assertsThe analogous loop in SparkFun library (https://github.com/sparkfun/SparkFun_MAX3010x_Sensor_Library/blob/master/examples/Example8_SPO2/Example8_SPO2.ino) features the following calls instead: while (particleSensor.available() == false) //do we have new data? particleSensor.check(); //Check the sensor for new dataSee the enclosed images. Thus, it's rather obvious what to do. I might add that the particleSensor.check() is complicated and rather expensive. If the sensor's hardware offers an instant INT signal replacing it, then why not use it?

Hmm, all drivers I know use interrupt line. Can you elaborate on your "other drivers do not use interrupt line"? Please provide links to relevant examples.

Sorry, I have never used ESP32 board.

Well, I am no expert regarding Maxim hardware, thus I simply copied Maxim's reference settings and never touched them again. However, I have done some Internet search and found out that in _other_ Maxim sensor this register controls the current of IR LED in proximity mode. This is an extra function that is activated when the sensor enters standby state, awaiting the object sensed. For more details see:https://datasheets.maximintegrated.com/en/ds/MAX86...https://datasheets.maximintegrated.com/en/ds/MAX30105.pdf

Thank you very much for good work!

Thanks for your interest. You provide no useful information at all, thus all I can do is to guess/speculate:1) Faulty sensor2) Bad connectionswhich is not satisfying and probably irritating, but what else can I do?Uncomment "#define DEBUG" line in the main code and collect raw signal data. Next,follow this linkhttps://github.com/aromring/MAX30102_by_RF/blob/ma...then scroll down to "How to report bugs" section.

Even though the I2C might work in the way you described for some time, you should never mix 3.3 and 5 V logic on the same bus. Otherwise, you will shorten lifespan of your sensor. Here are two links that contain detailed explanation:https://www.robotshop.com/community/blog/show/runn...https://www.nxp.com/docs/en/application-note/AN104...

Hi Radovan,Thank you for testing my little project. Yes, I am interested in test data; please send it to me, but please don't use the horrible Instructables mail or comments: it's been known to mangle the data. Instead, use my GitHub page for this project:https://github.com/aromring/MAX30102_by_RFsince at least it works OK with tab-delimited columns of numerical data as well as it can handle attachments. Besides, GitHub is much more appropriate for code related issues.I will also need an explanation of some terms you are using, like "artifacted PPG" - do you mean a PPG signal to which you added random noise? Furthermore, "SpO2 is going fine, giving no valid value during artifact" - now, which one is it: "fine", meaning OK, or "no valid value", meani…

Hi Radovan,Thank you for testing my little project. Yes, I am interested in test data; please send it to me, but please don't use the horrible Instructables mail or comments: it's been known to mangle the data. Instead, use my GitHub page for this project:https://github.com/aromring/MAX30102_by_RFsince at least it works OK with tab-delimited columns of numerical data as well as it can handle attachments. Besides, GitHub is much more appropriate for code related issues.I will also need an explanation of some terms you are using, like "artifacted PPG" - do you mean a PPG signal to which you added random noise? Furthermore, "SpO2 is going fine, giving no valid value during artifact" - now, which one is it: "fine", meaning OK, or "no valid value", meaning completely wrong? Is there any problem with SpO2? I am guessing the problem is with HR, correct? I am not sure what "some segment without artifact" exactly means, but it seems to me that you have observed the HR value that is half the expected rate. If this is the case, then this observation confirms a known bug: in my GitHub web page click "Issues" and take a look at the issue #6. It contains a precise explanation of all the reasons why it happens.

Ah, never mind. Only now I have realized that your "artifacted PPG" means a signal with motion induced artifacts - right? Sorry for not guessing it the first time.

Hi Andrew,Thank you very much for your interest in my work. I will be very happy to help you in resolving all issues - providing my very limited time allows it. (You've probably noticed I haven't published any new Instructable in quite a while - this is because my professional work clamped hard on my waking time.) Regarding your points a and b, let's switch our communication to GitHub since these items are code-specific. Alternatively, feel free to use Instructable's e-mail to send me a private message with your preferred e-mail address where I can reach you.

Hi Shea,Thank you for your interest in my work. Most scientific journals allow one "electronic resource" type of reference, which consists of the author's name, URL, and date of last access. You can use either a link to this Instructable or to my Github page; for example:Fraczkiewicz, R. https://github.com/aromring/MAX30102_by_RF, accessed 10/30/2019.I am curious about your code. Does it power a pulse oximeter, as well? Where will you publish it?

No, I haven't but other have done it and encountered a bug resulting in incorrect HR numbers reported at high heart rates. See the GitHub page for more details:https://github.com/aromring/MAX30102_by_RF

Hmm... Just scroll this page up to Step 6 - there is a link to the MAX30102 code.

Thank you for the update! :)

Thank you for your interest in my little project.As for your troubles: You provide no useful information at all, thus all I can do is to guess/speculate:1) Faulty sensor2) Bad connectionswhich is not satisfying and probably irritating, but what else can I do?Uncomment #ifdef DEBUG in the main code and collect raw signal data. Next,follow this linkhttps://github.com/aromring/MAX30102_by_RF/blob/ma...then scroll down to "How to report bugs" section.

4 seconds x 25 Hz = 100 samples. C arrays are indexed from 0, thus the sample indices run from 0 to 99. To mean-center these indices first calculate the mean ( = 49.5), then subtract it from each index and you get 0 - 49.5 = -49.5, 1 - 49.5 = -44.5, etc.

I am glad it is working now. It is impossible for me to tell why you see results so seldom without knowing much more details about your project. It could be a million different things. Uncomment #define DEBUG to capture raw data in Serial monitor. Next, for debugging instructions as well as some tips please follow this linkhttps://github.com/aromring/MAX30102_by_RF/blob/ma...then scroll down to "How to report bugs" section.

Here is the sum calculated in Excel to dispel any doubts: it is 83325, indeed. Try it yourself. Your formula, I think, applies to numbers from 1 to n only.Now, the matter of unchanging results is concerning since my device's results do change as I wrote in other answers below. If you think it's the result of a bug in my code, then for debugging instructions as well as some tips please follow this linkhttps://github.com/aromring/MAX30102_by_RF/blob/ma...then scroll down to "How to report bugs" section. Otherwise, the sensor may be faulty in which case you should contact Maxim.

Yes, you can.

First, let's get minor inconsistencies out of the way first: The "straight lines" you see in my plots in the second figure are an illusion caused by large vertical scales (matching the extent of noise caused by the original algorithm). In fact, both SpO2 and HR vary in time, although not much. If you don't believe me, then click in the lower left corner to download the original image and expand it.Second, I had the same question: how can I validate that MAX30102 even works? I did a few tests to convince myself. For example, I measured my heart rate at rest and after physical exertion. As expected, the HR went up in this experiment. I also compared the sensor output to independently measured HR by a Sleeptracker device I installed not so long after this project. The numbers and t…

First, let's get minor inconsistencies out of the way first: The "straight lines" you see in my plots in the second figure are an illusion caused by large vertical scales (matching the extent of noise caused by the original algorithm). In fact, both SpO2 and HR vary in time, although not much. If you don't believe me, then click in the lower left corner to download the original image and expand it.Second, I had the same question: how can I validate that MAX30102 even works? I did a few tests to convince myself. For example, I measured my heart rate at rest and after physical exertion. As expected, the HR went up in this experiment. I also compared the sensor output to independently measured HR by a Sleeptracker device I installed not so long after this project. The numbers and trends agreed, so I am a bit more confident that at least this part of measurements is working OK. I did not verify SpO2 in a similar manner, but there is a way to do it, too. Chances are that your doctor has a commercial HR/SpO2 meter. Bring your device to the next medical check up and compare the numbers. Unless you stay in your doctor's office overnight :) , there is no way to know that long time trends of both devices would agree, though.Therefore, if you still have concerns regarding your sensor, then you should address these with Maxim Integrated, Inc.

Yes, it's normal that once a while the signal quality does not meet standards and an indicator -999 is returned instead of the expected parameters. About serial plotting, I think you mean graphs posted in Step 2? Yes, that was Arduino IDE's plotter capturing live data. You must turn DEBUG on to get the raw data output.

Sorry, this is the first time I hear about "keil". I use Arduino IDE and am quite happy with it. Not knowing anything about keil indicates that I know even less about its libraries...Motion artifacts are not entirely about the sensor moving against the skin, but about moving muscles/tendons/etc. _under_ the skin. To the sensor, these are like loud sonic booms while you try recording bird songs. Hence, I am skeptical about MAXIM returning reliable data under these conditions. My setup, in particular, is almost guaranteed not to work - with a modicum of quality control the code would reject almost all signals. But not to discourage you, I admit that in my specific application I did not dedicate enough thought to combating these artifacts. Persistence is the mother of invention, so…

Sorry, this is the first time I hear about "keil". I use Arduino IDE and am quite happy with it. Not knowing anything about keil indicates that I know even less about its libraries...Motion artifacts are not entirely about the sensor moving against the skin, but about moving muscles/tendons/etc. _under_ the skin. To the sensor, these are like loud sonic booms while you try recording bird songs. Hence, I am skeptical about MAXIM returning reliable data under these conditions. My setup, in particular, is almost guaranteed not to work - with a modicum of quality control the code would reject almost all signals. But not to discourage you, I admit that in my specific application I did not dedicate enough thought to combating these artifacts. Persistence is the mother of invention, so I wish you good luck!

Thank you for the interest in my project. 1. Unfortunately, Arduino Uno is not powerful enough to execute this algorithm. I've learned it the hard way. :) But if you insist on using this platform, nonetheless, then you would have to go back to the original MAXREFDES117# code and see how they pulled it off. Basically, they've greatly sacrificed accuracy to save memory. For example, their uch_spo2_table[184] in algorithm.h is composed of uint8_t's instead of floats. I have retained some of their edits as comments in my code. IMHO, it's a losing battle not worth your time. It is much more efficient to just buy sufficiently powerful MCU.2. No, I haven't added an accelerometer. In fact, I have not touched this project since January 2018. One idea would be to use it to detect motion and hold sa…

Thank you for the interest in my project. 1. Unfortunately, Arduino Uno is not powerful enough to execute this algorithm. I've learned it the hard way. :) But if you insist on using this platform, nonetheless, then you would have to go back to the original MAXREFDES117# code and see how they pulled it off. Basically, they've greatly sacrificed accuracy to save memory. For example, their uch_spo2_table[184] in algorithm.h is composed of uint8_t's instead of floats. I have retained some of their edits as comments in my code. IMHO, it's a losing battle not worth your time. It is much more efficient to just buy sufficiently powerful MCU.2. No, I haven't added an accelerometer. In fact, I have not touched this project since January 2018. One idea would be to use it to detect motion and hold sample taking until motion ceases. But in the case of your pets there may not be any periods of rest, especially considering dogs. :) The obvious idea then is to combine signal from accelerometer and SpO2 sensor to subtract motion artifacts. How? If I were to do it I would find out through experimentation...3. Our pets use hemoglobin to transport oxygen, just like us. Thus, the basic principles of the sensor operation should be satisfied. But MAXIM's sensors might be already calibrated for human skin, thus would not work on animals. Honestly, I don't know; better ask MAXIM about it.

Hi, for debugging instructions as well as some tips please follow this linkhttps://github.com/aromring/MAX30102_by_RF/blob/ma...then scroll down to "How to report bugs" section.

I wish I had powers of the Wizard of Oz, or at least those of a proficient mind reader, to be able to correctly guess what the problem is when given almost zero information about your system. Especially the one involving sensor I have never tested.Let's do this: follow this linkhttps://github.com/aromring/MAX30102_by_RF/blob/ma...then scroll down to "How to report bugs" section, OK?

Awesome work! Thank you for sharing. My oscilloscope can show frequency and duty cycle, too, but I wanted something battery operated and portable.So, ARM Cortex M3! At 72 MHz it looks even better than M0. With it, can you measure frequencies above 1 MHz? Is that the Blue Pill board you are using? Where did you buy it? Did you have to replace its D+ resistor to make it work with USB? I am guessing it does not work with Arduino IDE, does it?

Thank you for an interesting suggestion. I looked Nomorob up and learned that it (currently) works only on VoIP lines. Hence, creating the "first ring killer" would be a whole new project which would be, I suspect, quite different from this Instructable that works on POTS lines...

This should not be much of a problem, since the same reference design, MAXREFDES#117, should work with MAX30101. According to MAXIM: https://maximintegratedsupport.force.com/support/s...the only modification is an additional green LED that may need to be connected. Now, the ease of hardware design does not compare to the complexity of a new application you (probably) have in mind: monitoring HR/SpO2 during exercise, right? Wrist mount and huge motion artifacts pose significant problems and my code is not designed to deal with these. An additional accelerometer is required to compensate, at somewhat, for this additional noise. Fortunately, MAXIM offers such a kit that you may want to consider:https://datasheets.maximintegrated.com/en/ds/MAX30...https://www.maximintegrated.com/en/products/s…

This should not be much of a problem, since the same reference design, MAXREFDES#117, should work with MAX30101. According to MAXIM: https://maximintegratedsupport.force.com/support/s...the only modification is an additional green LED that may need to be connected. Now, the ease of hardware design does not compare to the complexity of a new application you (probably) have in mind: monitoring HR/SpO2 during exercise, right? Wrist mount and huge motion artifacts pose significant problems and my code is not designed to deal with these. An additional accelerometer is required to compensate, at somewhat, for this additional noise. Fortunately, MAXIM offers such a kit that you may want to consider:https://datasheets.maximintegrated.com/en/ds/MAX30...https://www.maximintegrated.com/en/products/sensor...

I have just finished a similar project of converting my old Sony Digital8 camcorder into a microscope. The differences are:1. I bought an extra macro lens for it (found by camera type on Amazon), which lets me achieve quite good magnifications up to 60x. Useful in detecting microscopic solder cracks. :)2. It is connected through a FireWire to my old iMac. The iMovie software nicely interfaces with it and lets me record and edit videos.3. The camera mount is motorized 9made out of an old professional CD burner), but it moves it only up and down. Seems your boom arm is better in this respect.

This question has just been resolved over e-mail.

Nice project, thank you for sharing. There seems to be only one tiny bug in the code as posted. In the main loop you have the following construct: if ((analogRead(0)>130) && (analogRead(0)<160)) { <part 1> } else if ((analogRead(0)>130) && (analogRead(0)<160)) {<part 2>}Huh? Apart from the missing last bracket, <part 2> will never execute.

On a car - that would increase car's air resistance. So, yes, you would get electrical energy (with very poor efficiency) at a cost of burning more gasoline.

Thank you. Wow, you've been very productive: 53 Instructables! However (correct me if I'm wrong), none of these involves phone hacks. Please share at least some these since I'm at the moment interested in landline phone electronics.About the ringer-off switch: Do you solemnly swear to dutifully and manually turn the ringer off every evening and back on every morning? :)Although my phone has such a switch, too, I am not that disciplined. I have better things to do than remembering about the switch all the time... This is what machines are for.

Done, in Step 3.

Very nice work. There is only one tiny snafu: your LED screen still reads "SYSTEM ON" when it's in the OFF state.

Thank you. Yes, timed switch would also work (although you wouldn't be able to make calls). There are many ways to skin a cat. ;) In fact, Amazon sells an ordinary switch + RJ11 jack combo for $15!https://www.amazon.com/Telephone-connected-Interru...Amazing what nowadays people make money on. :)

Thank you for excellent tips!