I have been attempting to get a muscle sensor kit from sparkfun working(MyoWare 2.0 Muscle Sensor - DEV-21265 - SparkFun Electronics). However after hooking everything and running the code provided on the website it seems to return random noise in the serial monitor - the values varying from 200 to 500, whether the muscles sensor are connected or not. What I'm trying to figure out is if there is a problem with my circuit boards, connections or code...
Here is the code I'm using and a photo:
// reads analog input from the five inputs from your arduino board
// and sends it out via serial
// variables for input pins and
int analogInput[6];
// variable to store the value
int value[6];
void setup()
{
// declaration of pin modes
for(int i=0;i<6;i++)
{
analogInput[i] = i+1;
value[i] = 0;
pinMode(analogInput[i], INPUT);
}
// begin sending over serial port
Serial.begin(9600);
}
void loop()
{
// read the value on analog input
for(int i=0;i<6;i++)
{
value[i] = analogRead(analogInput[i]);
}
// print out value over the serial port
for(int i=0;i<6;i++)
{
Serial.println(10000 + i + 1); //prefix
Serial.println(value[i]);
Serial.println(10010); //end signal
}
// wait for a bit to not overload the port
delay(10);
}
robtillaart:
better read all pins twice and use the last read
I've seen that suggested before Rob: what does it actually do that reduces the problem? (Why would a second read be any more trustworthy than the first?)
It is indeed un-logical now that I think about it... The code is just copied from the manufactures website http://www.advancertechnologies.com/p/muscle-sensor-v3.html while the setup is based of the user manual - I naively assumed that the provided example code would work with the setup in the manual. I guess that answers my question - I need to change the code or the setup. Unfortunately I am new to arduino, and have no idea how to write the code required.
So my next question is:
Does anybody have any idea about how to write a basic code that would allow me to see the sensors output in the serial monitor? (This is probably a really basic thing to do, but I am very amateurish at this so any help would be much appreciated)
JimboZA:
I've seen that suggested before Rob: what does it actually do that reduces the problem? (Why would a second read be any more trustworthy than the first?)
There is only one ADC in the AVR chip which is multiplexed.
By using 2 reads the ADC has more time to adjust/stabilize to the other value.
Hey Brian, there is a link to an image below the code called MS_VS-2.
Cheers,
Adam.
Didn't notice the attachment! Everything looks fine in the pics but you dont show the power supply nor the electrode placement (Usually the culprits). What voltages are you reading at pins +Vs and -Vs w.r.t. ground?
Still a little hard to see which battery wire is going where.
It looks like...
the left battery's black wire is connected to the GND pin, and its red wire to +Vs.
the right battery's black wire is connected to the -Vs pin, and its red wire to GND.
which would be correct.
Did you solder the wires to the board or are they just stuck in the board's pin holes?
BTW you only have to connect either the board's ground to the arduino's ground or the battery's ground to the arduino's ground. It looks like you have both. While this is technically OK, it's not necessary.
Hey Brain, using the analog read serial code has been working better, although it still returns noise. I soldered female headers to the board - I didn't want to commit to soldering the wires but figured it would be a bad idea to leave them hanging loose. Thanks, I didn't realize it only needed one or the other.
Hi, dllyod what would you recommend doing if the gain adjustment is out of range? (Sorry bit of a noob so I don't really know what that means)
mooreadam:
Hey Brain, using the analog read serial code has been working better, although it still returns noise. I soldered female headers to the board - I didn't want to commit to soldering the wires but figured it would be a bad idea to leave them hanging loose. Thanks, I didn't realize it only needed one or the other.
Hi, dllyod what would you recommend doing if the gain adjustment is out of range? (Sorry bit of a noob so I don't really know what that means)
Cheers,
Adam.
I wouldnt recommend messing with the gain. The default setting should be fine.
Can you paste the output youre seeing? Also, did you see me ask about the voltages at +Vs and -Vs pins?
Looks like the gain control uses a 100K pot ... if set to max (100K), the gain would be 20,700. If set to max, I would guess that the circuit would be highly susceptible to noise.
Here, this simplified sketch can be used to calibrate the sensor board. It just continuously reads analog input A0 and prints the reading. Arduino's LED turns on when 1023 is reached.
When testing with a sensor pad, if you find that its too easy to get maximum reading of 1023, then you could turn back the pot until it takes the desired maximum effort to get the maximum reading of 1023.
int value;
void setup()
{
pinMode(13, OUTPUT);
Serial.begin(9600);
}
void loop()
{
value = analogRead(A0);
Serial.println(value);
if (value == 1023) {
digitalWrite(13, HIGH);
}
delay(100);
digitalWrite(13, LOW);
}
EDIT:
Have you checked the charge (voltage) on both batteries?
They should preferably have similar voltage levels.
Looks like the gain control uses a 100K pot ... if set to max (100K), the gain would be 20,700. If set to max, I would guess that the circuit would be highly susceptible to noise.
Here, this simplified sketch can be used to calibrate the sensor board. It just continuously reads analog input A0 and prints the reading.
When testing with a sensor pad, if you find that its too easy to get maximum reading of 1023, then you could turn back the pot until it takes the desired maximum effort to get the maximum reading of 1023.
int value;
void setup()
{
Serial.begin(9600);
}
void loop()
{
value = analogRead(A0);
Serial.println(value);
delay(100);
}
EDIT:
Have you checked the charge (voltage) on both batteries?
They should preferably have similar voltage levels.
But when put on the muscle sensors every turns to 0.
Sorry, this is probably a dumb question but do you want me to test the vs pins with a multimeter or through arduino? I ran this sketch to test the voltage but not sure if thats what you meant...
