Hello, I’ve been a user of the original Myoware sensor for a while and now I’m trying out the 2.0 sensor. I’ve attached my setup below, but as you can see my analog serial output is flatlined at 1023 despite my best attempts to fix it. I imagine this is probably something simple on my end that needs fixing. The electrodes were swapped, the Redboard TRS shield jack was tested from A0 to A5, and my skin was thoroughly cleaned with alcohol beforehand. Without the sensor attached, the analog serial output is pretty much zero, as expected. I just hope that the problem isn’t a bridged connection within the board itself, but it arrived yesterday so I doubt it.
Please let me know if there’s something I should do.
I have zero experience with this, but intrigued enough to watch through Rob’s montage - what a hoot. Looks like you are connecting to the laptop; did you read on the hookup guide about using a usb isolator (or running the laptop from batteries with wireless mouse and keyboard)?
Yeah, I agree with languer’s comment. I can’t tell from your setup but make sure to disconnect your laptop from the power grid or use a USB isolator. Although, I think you might know this already from working with the previous version.
I think you should check the placement of the MID and END electrodes again. The electrodes do not look like they are lining up with the muscle group in the second image. The reference electrode also appears to be slightly offset from the muscle group when it should be adjacent to the muscle group. This could be why you are seeeing the sensor “saturate” and not responding as expected to your forearm. Try rotating the stack about 90 degrees clockwise so that the MID and END electrodes align with the forearm muscle. I am not able to see the whole arm but you may want to shift it just a bit closer toward your elbow as well to get more muscle fibers. The image shown below was taken from the [MyoWare 2.0 Advanced User Guide. If you need a closer look, try looking at that PDF and zooming in.
The laptop is running off of battery charge so it is isolated from wall power. The sensor produces a saturated output without even being connected to my arm at all, and it seems impossible to ground it. The muscle placement changes do not make a difference in the same regard. On a separate note, the Artemis Redboard I was using seemingly died overnight while the sensor was connected. No power was running to the board that night and now even the power light will not respond unless manually given a voltage via multimeter (the board isn’t even detected by usb ports anymore). You can imagine this is becoming frustrating.
Sorry, I do not check the forums that much but I wanted to follow up on your post. Hmm, I am not entirely sure why your RedBoard Artemis would not power up after not being connected to power overnight. My only guess is that the PTC was tripped somehow. However, that should be fine after a few seconds and then unplugging/replugging the board back into your computer’s COM port. I assume that all the connections are secure and fully connected.
I am not entirely sure why the muscle sensor is not reacting even when placing the sensor correctly on the muscle group. Have you tried adjusting the trimpot and lowering the gain?
If the sensor still is not functioning let me know. I checked in with one of the tech support reps and he is aware of your case.
I connected the ENV pin to Arduino Uno A0. It sends value 18 with some noise. When I move my muscles on the arm, the value doesn’t change much, maybe going to 15 and 21, which are about the same as the noise I get when the probes are not connected to anything. It never goes to 0 either.
I’m using M1 MacBook Air, which I made sure to unplug from the wall charger. I also tested with MacBook Pro 2015 to see if something would change, but Myoware 2 gave me the same 18s. I double-checked the wiring and soldering on the sensor with a multimeter, and they all look good.
I found this thread on Reddit. Is there any chance that my sensor is a defect?
“After talking with Sparkfun (who manufactures the sensors now), I would recommend you contact them. A portion of the QA testing was accidentally skipped with the first batch of sensors.”
bboyho:
Sorry, I do not check the forums that much but I wanted to follow up on your post. Hmm, I am not entirely sure why your RedBoard Artemis would not power up after not being connected to power overnight. My only guess is that the PTC was tripped somehow. However, that should be fine after a few seconds and then unplugging/replugging the board back into your computer’s COM port. I assume that all the connections are secure and fully connected.
I am not entirely sure why the muscle sensor is not reacting even when placing the sensor correctly on the muscle group. Have you tried adjusting the trimpot and lowering the gain?
If the sensor still is not functioning let me know. I checked in with one of the tech support reps and he is aware of your case.
The sensor and board are still not functioning, albeit I didn’t mess with the trimpot yet because I doubted that I should mess with the gain since it should be properly set on arrival so that it isn’t hitting max. As you mentioned, I contacted support directly and they offered a replacement so hopefully that will be arriving in the days to come. I assume something weird happened in shipping or I was just really unlucky.
The replacements for the redboard and sensor came in but the problem remains the same. I’m ordering a new TRS cable and planning on getting it in 2 days from the corporate overlords.
To reiterate: No it is not the sensor placement. I have moved the sensor around. If I always output a max signal I would be the strongest person on the planet, and always flexing as well. I have read the manuals on the sensor website as soon as I got it, respectfully stop linking me the same pages. I have used the original myoware sensor a ton already to control prosthetics. This sensor is seems simple since you snap it together and just plug in a TRS, so I’m hoping its the TRS at this point or I will be retiring and beginning my new life in the sewers. Still hoping for someone to see something I can’t here.
I connected the ENV pin to Arduino Uno A0. It sends value 18 with some noise. When I move my muscles on the arm, the value doesn’t change much, maybe going to 15 and 21, which are about the same as the noise I get when the probes are not connected to anything. It never goes to 0 either.
I’m using M1 MacBook Air, which I made sure to unplug from the wall charger. I also tested with MacBook Pro 2015 to see if something would change, but Myoware 2 gave me the same 18s. I double-checked the wiring and soldering on the sensor with a multimeter, and they all look good.
I found this thread on Reddit. Is there any chance that my sensor is a defect?
“After talking with Sparkfun (who manufactures the sensors now), I would recommend you contact them. A portion of the QA testing was accidentally skipped with the first batch of sensors.”
Make sure that you are placing the sensor correctly on the target muscle and the EMG pads are making good contact with the skin. Otherwise, you can get bad sensor readings. I’m not sure how you are connecting the sensor to your Arduino. What is your pin connections and boards that you are using?
ddorf:
The replacements for the redboard and sensor came in but the problem remains the same. I’m ordering a new TRS cable and planning on getting it in 2 days from the corporate overlords.
To reiterate: No it is not the sensor placement. I have moved the sensor around. If I always output a max signal I would be the strongest person on the planet, and always flexing as well. I have read the manuals on the sensor website as soon as I got it, respectfully stop linking me the same pages. I have used the original myoware sensor a ton already to control prosthetics. This sensor is seems simple since you snap it together and just plug in a TRS, so I’m hoping its the TRS at this point or I will be retiring and beginning my new life in the sewers. Still hoping for someone to see something I can’t here.
unnamed.jpg
Hi ddorf ,
I’m not sure why the replacements are not working.
I do remember there were issues when using a TRRS-to-TRRS cable and a TRS-to-TRS cable was required. Did you initially get a TRS-to-TRS cable from our storefront?
Are you seeing the same response when the Arduino is not on top of your laptop? I’m not sure if you would like to try the Bluetooth route to read the sensor readings wirelessly?
The sensor placement in your picture appears to not be connected to the target muscle. The “GND” of the Link shield is directly over the “REF” electrode when the shield is stacked on the sensor. It appears to be connected to the middle of the muscle group. I am not sure if you have tried rotating the sensor 90° counter clockwise on your left arm so that the TRS cable comes out of toward the right of your arm? Of course, make sure to align the “MID” and “END” electrodes along the muscle as you normally would.
so hopefully that will be arriving in the days to come. I assume something weird happened in shipping or I was just really unlucky.
