Controlando o brilho do Led usando meditação e nível de atenção (Parte 5/13)

Controlling LED brightness using meditation and attention level (Part 5/13)

June 25, 2024 Roberto Magalhães

Controlling LED brightness using meditation and attention level

SUMMARY

After talking about the theoretical concept of brain waves, it's time to check out some real-time applications. Here, we will discuss the efficiency, flexibility and various features of what we have done so far. I'm currently thinking about changing something depending on my level of attention and meditation, say the brightness of a small LED. We will be controlling the brightness of an LED using our brain's attention and meditation levels at any specific moment. We will be using Arduino UNO and flexible mind sensor that we chose to read the brain wave and an LED to show the results. DESCRIPTION We are changing the brightness of LED which can be easily controlled using PWM Technique . Quick note: PWM is a technique for controlling analog devices via digital outputs. Through the digital outputs, we are creating a square wave of ON and OFF patterns. This ON and OFF pattern is used to create analog voltage varying between Low Voltage and High Voltage and we can vary the voltage by changing the duration of the ON time in relation to the OFF time. If we pass this ON OFF pattern to the LED at high speed, apparently an analog voltage is received and its brightness changes accordingly. First, let's control the LED brightness using the attention level. So, now to control the brightness of an LED, we will measure the attention level of and meters of the TGAM1 chip. Note that this chip gives us the level of attention on a scale of 0 to 100. It is also interesting to know that the chip transmits the Meditation signals only when the sensor is accurately connected to the Brain and the sensor module is receiving 100% of the signal. strength. Signal strength varies from 0 to 200.

Imagem mostrando o brilho de um LED sendo controlado pelo nível de meditação usando sensor de ondas cerebrais

Fig. 1: Image showing the brightness of an LED being controlled by the meditation level using a brainwave sensor

Dramatically, when the signal strength is 100%, the sensor sends the value 0 and when the sensor sends 200, it means there is no connection of the metal sensor with our brain. So, after confirming that our signal strength is 100% and that our sensor is sending 0 in series for signal strength, we can perform this experiment. Now as we know that PWM has a duty cycle that determines the analog level. The duty cycle is basically the time divided by the total period. To change the LED brightness based on attention level, we will change the PWM duty cycle. Since we are getting the sensor meditation value on a scale of 0 to 100, we will make the duty cycle value equal to the meditation value subtracted from 100. For example, if the sensor meditation value is 40, then the duty cycle is 100–40 = 60.

Imagem mostrando o brilho de um LED sendo controlado pelo nível de meditação usando um sensor de ondas cerebrais

Fig. 2: Image showing the brightness of an LED being controlled by the Meditation Level using the Brainwave Sensor

This will make the LED brightness parallel to the meditation level. You can check the code and video of this experiment. After the meditation level, we will do the same with the attention level. Just to remind you again, check if the signal strength is reaching 100% and with a value of 0.

Fig. 3: Image showing the brightness of an LED being controlled by the Meditation Level using the Brainwave Sensor

We again need to remove the attention values from the sensor and change the PWM duty cycle in relation to the attention values. Again, make the duty cycle value equal to the attention value subtracted from 100. For example, if the sensor meditation value is 40, the duty cycle will be 100 – 40 = 60. Check out the software section to see how PWM is implemented in code. And we also finish the brightness control using attention values. Check out the code and video to perform the experiment yourself.

Diagrama de blocos do controlador de brilho LED baseado no sensor MindFlex Brainwave

Fig. 4: Block diagram of LED brightness controller based on MindFlex Brainwave sensor

Hardware: Please find the attached circuit diagram of the connections we need to make. We take a pin from the T pin of the mindflex sensor and connect this pin to the Rx pin of our Arduino UNO. Additionally, we short-circuited the Sensor and UNO ground by a wire. Please take special care when soldering anything to the Mindflex sensor as the pins are very close to each other.

Programs: Let's go to the software part. We have been receiving the E meter values from the sensor to our arduino via T pin. Once we receive the value at any specific point, we just need to convert that value level to the LED brightness. As discussed earlier, we will use PWM techniques. PWM on Arduino is done by analogWrite: E.g.

AnalogWrite(13,240);

AnalogWrite in Arduino is used to write PWM wave to a pin. In the example above, the first parameter is the PIN number and the second is the PIN value. So we are writing 240 on pin 13. Now we can easily calculate the analog voltage at value 240. The total voltage range is 0V to 5V and the value range is 0 to 255.

This means 240 = (5/255)*240 = ~4.70V.

Now, the values we get for and meters are in the range 0 to 100.

So let's say we get evalue = 70.

We will multiply the value of e by 2.55 to put it in the range 0 to 255.

So it will be analogWrite (pin,evalue*2.55) in a loop.

Some points to note:

The sensor usually provides 60 to 80% resistance due to its orientation and the location where we place it. Try to keep the metal sensor exactly above your left eye. I also applied salt water to my forehead for better connectivity with the sensor. If you don't find 100%, then it's normal. In the next articles, I will explain how we can control various objects without signaling attention and meditation values.

The signal strength also messes with how we solder the wire to the T pin. Try shielding this wire and also make sure the reference probes are connected correctly. If you have any wires connected to the sensor's EEG Pin, disconnect that wire, as this will create noise in the sensor values.

Try this experiment and let me know if you have any problems. Stay tuned for more Brainwave-based experiments related to controlling a motor.

Project source code

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 //Program to

#include

// Configure the brain analyzer, pass it the hardware serial object you want to listen to. Brain (Serial); //char a(400); Sequence a,a1; int v = 0; int z=0,output; uint32_t num=0; uint32_t num1=0; empty configuration { // Start the hardware serial. Serial.begin(9600); pinMode(9, OUTPUT); } empty loop { // Expect packets about once per second. // The .readCSV function returns a string (well, char*) listing the most recent brain data, in the following format: // "signal strength, attention, meditation, delta, theta, low alpha, high alpha, low beta, high beta, low gamma, high gamma" if (brain.update ) { //Serial.println(brain.readErrors ); //Serial.println(brain.readCSV ); //sprintf(a, "%c",brain.readCSV ); a = brain.readCSV; v = a.indexOf(','); v = a.indexOf(',',v+1); v = a.indexOf(',',v+1); v = a.indexOf(',',v+1); z = a.indexOf(',',v+1); a1 = a.substring(v+1,z); num = a1.toInt ; v = a.indexOf(',',z+1); a = a.substring(z+1,v); num1 = a.toInt; //Serial.println(num); Serial.println(num1); analogWrite(9, output) //brain.readCSV .toCharArray(a,200); } }

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