Issue with Myoware Muscle Sensor with LED Shield

Sensors Biometrics
1

The sensor with the LED shield seems to work fine by themselves. LED fills up with contraction and stays off when relaxed.

The sensor powered by the Arduino also works as expected. I get readings from 0-800 and they correspond promptly with muscle movement.

However, when I connect the signal cable to Arduino, the serial monitor simply fluctuates from low to high values. The LED shield responds to muscle movement as expected, but the values don’t respond to the movements. Here is a sample output with a 100ms delay between readings. Also notice that after each cycle, it stops for a second before restarting. It does not do that when the sensor is not using the LED shield.

01:22:07.072 → A1 1023

01:22:07.174 → A1 1023

01:22:07.243 → A1 1023

01:22:07.344 → A1 1023

01:22:07.447 → A1 903

01:22:07.550 → A1 720

01:22:07.654 → A1 508

01:22:07.756 → A1 252

01:22:09.782 → A1 15

01:22:09.852 → A1 154

01:22:09.955 → A1 424

01:22:10.059 → A1 714

01:22:10.163 → A1 1015

01:22:10.265 → A1 1023

01:22:10.368 → A1 1023

01:22:10.472 → A1 1023

01:22:10.575 → A1 1023

01:22:10.677 → A1 1023

01:22:10.781 → A1 1023

01:22:10.884 → A1 1023

01:22:10.954 → A1 1023

01:22:11.056 → A1 1023

01:22:11.158 → A1 1023

01:22:11.261 → A1 1023

01:22:11.365 → A1 1023

01:22:11.471 → A1 924

01:22:11.573 → A1 756

01:22:11.676 → A1 543

01:22:11.779 → A1 291

01:22:11.882 → A1 24

Can you not use the LED shield and get the signal at the same time? Any help would be greatly appreciated. Thanks.

2

Just an update. I realized that if I have one Myoware sensor that is powered directly by the Arduino, then all the other battery powered sensors start working normally.

3

Hi wkwong,

Correct me if I am wrong but it sounds like the issue may be fixed. That said, the reason you were seeing a bunch of weird data from the sensor when you just had the signal line plugged in while the LED shield was powering the MyoWare is most likely because the analog voltage from the signal pin had no ground reference for a “0” output. Try connecting both the SIG and GND (or the - pin) pins to a ground pin on your Arduino (but leave + or RAW disconnected since I would avoid using the battery-powered shields with a MyoWare sensor powered from an external source like an Arduino since you may damage the power lines from over-voltage) and that should get you an accurate analog output from the Arduino.