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MyoWare Muscle Sensor Kit
Introduction
As announced previously, Advancer Technologies started a Kickstarter
campaign to produce an updated version of their Muscle Sensor v3 board.
The MyoWare™ Muscle Sensor (AT-04-001) is the latest electromyography
(EMG) sensor from Advancer Technologies. Here is an overview of the
MyoWare product line and how to use it.
Figure 1. MyoWare main sensor board
MyoWare Muscle Sensor
A new version means new features. Here is a breakdown of the new
features added to the MyoWare Muscle Sensor Board:
Single-supply — MyoWare won’t need ± voltage power supplies! Unlike
the previous sensor, it can now be plugged directly into 3.3V - 5V
development boards.
Embedded Electrode Connectors — Electrodes now snap directly to
MyoWare, getting rid of those pesky cables and making the MyoWare
wearable!
RAW EMG Output — A popular request from grad students, the MyoWare
now has a secondary output of the RAW EMG waveform.
Polarity Protected Power Pins — The #1 customer request was to add
some protection so the sensor chips don’t burn out when the power is
accidentally connected backwards.
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ON/OFF Switch — Speaking of burning out the board, Advancer
Technologies also added an on-board power switch so you can test your
power connections more easily. It’s also handy for saving power.
LED Indicators — Advancer Technologies added two on-board LEDs one
to let you know when the MyoWare’s power is on and the other will brighten
when your muscle flexes.
For more information, please have a look at the official MyoWare Muscle
Sensor datasheet.
What is electromyography (EMG)?
An EMG is used to record (graph) the electrical activity (electro) of muscles
(myo).
Embedded Electrode Connectors
The embedded electrode connectors allow you to stick the board right to
the target muscle and avoid the hassle of wires.
Embedded electrode connectors
The embedded snap connectors mate well with our Biomedical Sensor Pad
(10 pack).
Cable Shield
There may still be cases where you want to mount the sensor pads away
from the other hardware. For these cases, we sell the MyoWare Cable
Shield.
MyoWare Cable Shield
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The cable shield provides a jack where you can attach the three electrode
cable shown here.
Three electrode cable
Instead of attaching the sensor pads to the MyoWare Muscle Sensor,
attach them to the end of the cable. Both sets of contacts are connected, so
make sure to only use one pad for each (Reference, End, and Middle).
Power Shield
MyoWare Power Shield
The MyoWare Power Shield is designed to take two coin cell batteries such
as some standard CR2032s. They are connected in parallel for extended
capacity at a nominal 3.0V. One thing to note is that due to the size of the
batteries, the remote cable header can’t be passed through. If you need
access to these connections, this Power Shield must be stacked above the
board(s) that need access.
Battery power allows for a cleaner signal and also eliminates the possibility
of creating a dangerous current path to the power grid.
Proto Shield
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MyoWare prototyping shield
The MyoWare Proto Shield passes all signals to a bit of protoboard. Use
this area to solder on whatever custom circuitry you can come up with.
The Cable Shield and the Proto Shield have two rows of 3-pin plated
through holes on each end. This allows ‘standard’ 0.1" headers to be used
to stack them with other boards. Use the outer rows to connect to the
Muscle Sensor, connect these two boards with the inner rows. The outer
row on the top can also be used to stack another shield on top for a total of
4 boards in a stack.
LED Shield
For those users looking for a large display of the signal level, we offer the
the MyoWare LED Shield.
MyoWare LED Shield
The LED shield provides a large 10-segment bar graph corresponding to
the level of the muscle signal measured. This shield is likely to be the top
board in a stack. Solder on some 1x3 male headers, and plug it into the
sensor board. The power is supplied on the LED shield, but controlled by
the power switch on the sensor. Once the stack is assembled, snap on
some electrodes, and stick the sensor on the target muscle.
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MyoWare LED Shield on an arm
The more muscle activation measured, the higher up the board the lit LEDs
will go. In the image above, the two segments near the ‘MIN’ label are lit,
and, if the voltage measured were to increase, the segments to the left
would begin to light until the last one labeled ‘MAX’ is reached. The LEDs
are bright enough to be seen in full light, but really glow nice in low light.
MyoWare LED Shield in the dark
Putting it All Together
As mentioned above, there are two ways to attach the sensor pads to a
user. They can be attached directly to the sensor board, or to the the end of
a cable via the MyoWare Cable Shield.
In the image below, the left most electrode connection should be connected
to the muscle being measured. This is equivalent to using the red insulated
conductor on the cable. The mid muscle electrode on the right breaks out
on the black snap. The reference electrode has continuity with the blue
snap on the cable.
MyoWare sensor layout
As shown in the image above, there are three rows of three 0.1" spaced
plated through holes. On the right is the power supply +Vs, & ground, along
with the processed output signal (holes 1, 2, & 3).
Along the long edge near the mid muscle electrode snap are the thru-holes
for remote electrode connection (holes 4, 5, & 6).
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On the opposite end are three ‘outputs’. Hole 7 is the raw, unprocessed
EMG signal. Hole 8 is the switched power. Power goes into the board via
hole 1, is switched, and comes back out hole 8 ( if you believe in passive
sign convention (PSC) ). Hole 9 is the ground reference for the switched
power.
The shields come with assorted support for these pins. Some shields such
as the Power Shield don’t support the remote connections. If you need
access to these pins the boards that use or can pass them through must go
lower in the stack. Both the Cable Shield and the Proto Shield have this
connection capability.
Danger! The power shield and the LED shield both provide power, but
at slightly different voltages. Don't use both of these shields at the
same time.
MyoWare Power Shield (top view)
MyoWare LED Shield (top view)
MyoWare Cable Shield (bottom view)
MyoWare Proto Shield (top view)
Take note of the second row of holes on the Cable and Proto shields. This
allows for stacking multiple shields using standard 0.1" headers or the
stackable variety.
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Break Away Headers Straight
Female Headers
PRT-00 115
PRT- 00116
Stackable Header - 3 Pin
(Female, 0.1")
PRT- 13875
The MyoWare sensor should be populated with female headers. If using the
stackable headers supplied with the kit, it is likely that you will want to flush
cut the long leads from the bottom. It’s possible to use a setup including the
cable shield, where you might want to leave them, so we’ve given that
option. The shield desired to mate with the MyoWare sensor should in most
cases have male headers populated on the outer bottom rows to mate with
the female headers. If using the parts provided on the kit, these male
headers will likely be the bottom half of stackable headers. The top side of
this shield can then be populated with female headers. The next board in
the stack will then need male headers on the bottom inside. This shield can
have female headers mounted to the outside row on the top side.
To make stacking easier, the MyoWare Muscle Sensor Kit includes 3-pin
stackable headers. Using these on all of the shields allows for easy
stacking in more configurations. Note: We have included three 1x3 male
headers in the kit. The normal use case will to be to put two of them on the
LED shield, but some of you might want a clean top surface on the cable or
proto shields so we thew in an extra one for this option.
3 pin stackable header
Resources and Going Further
Thanks for reading. For more information on the MyoWare product line,
please visit the following links.
• Official MyoWare™ datasheet
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• Advancer Technologies Website
• MyoWare GitHub Repository For more cool projects and ideas,
check out the following SparkFun tutorials.
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Learn how to create your very own
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MyoWare Muscle Sensor Kit
MAX30105 Particle and Pulse
Ox Sensor Hookup Guide
Line of products to work with the
MyoWare muscle sensor from
Advancer Technologies
The SparkFun MAX30105 Particle
Sensor is a flexible and powerful
sensor enabling sensing of distance,
heart rate, particle detection, even
the blinking of an eye. Get ready.
Set. Shine!
https://learn.sparkfun.com/tutorials/myoware-muscle-sensor-kit?_ga=1.210083858.648079... 1/16/2017