Entra y aprende a utilizar el HCSR04, el sensor ultrasnico de arduino ms comn. No te pierdas el cdigo listo para aplicar directamente en tu proyectoWhat is the best way to access a serial port from VBA I have a need for some of our sales reps to be able to send a simple string over the serial port from an action. American Journal of Engineering Research AJER 2016 w w w. Page 362 Serial. println digitalWriteledpin, LOW V. CONCLUSION. This is the new Arduino Uno R3. In addition to all the features of the previous board, the Uno now uses an ATmega16U2 instead of the 8U2 found on the Uno. MPU6050 6dof IMU for autoleveling multicopters. Auto leveling a multicopter is pretty challenging. It means that when you release the pitch and roll controls on. Secret Arduino Voltmeter Measure Battery Voltage A little known feature of Arduinos and many other AVR chips is the ability to measure the internal 1. Streaming Cstyle Output with Operator ltlt Note Streaming 5 is now Arduino 1. New users sometimes wonder why the Arduino language doesnt. Last week, we learnt about the basic structure of an Arduino program and took a closer look at the blink example. Hopefully you took the opportunity to experiment. Arduino Breathalyzer Calibrating the MQ 3 Alcohol Sensor. Difficulty Level 3Whats thisThe MQ 3 is an alcohol gas sensor that is available for about 5 from Sparkfun, Seeed Studio, and others. Its easy to use and has sparked the imagination of anyone who has dreamed of building their own breathalyzer device for measuring the amount of alcohol in the human body. I got an MQ 3 sensor a couple of months ago and have spent a lot of time trying to figure out how to do this. After lots of data gathering, I found that this task is not as easy as it sounds. MQ 3 Alcohol Sensor. First of all, dont try to use the MQ 3 as a way to determine if you are sober enough to drive. If youve been drinking, just dont drive And if youve had a few drinks, dont do any soldering either. The Circuit. The MQ 3 has a 6 contacts which is confusing, but not as confusing as the MQ 3 datasheet. I also got the Sparkfun breakout PCB for the MQ 3 so it makes the pinout easier to understand. Basically, there is a heater which you power by connecting to VCC and GND. Arduino Serial Output To Excel' title='Arduino Serial Output To Excel' />The heater draws about 1. A of current, so I would not power the heater directly from an Arduino board and certainly not from an output pin. The Arduino voltage regulator can handle 8. A, but you need to consider the power dissipation capability of that voltage regulator, too. I think its best to power the heater from an external source, like a regulated 5. V power supply or a 7. The other part of the circuit is essentially a variable resistor inside the sensor. B56FFA7220E01D7' alt='Arduino Serial Output To Excel' title='Arduino Serial Output To Excel' />The resistance across an A pin and a B pin varies depending on how much alcohol is in the air in the sensor. Program Management Approach. The more alcohol, the lower the resistance. We measure alcohol in the breath by measuring this resistance. Instead of measuring the resistance directly, we measure the voltage level at the point between the sensor and a load resistor. The sensor and load resistor form a voltage divider, and the lower the sensor resistance, the higher the voltage reading will be. An Arduino analog input pin is a good way to measure the voltage and gives us a reading between 0 and 1. Higher values mean more alcohol. One more caveat that every MQ 3 owner needs to know the sensor has a 2. That is, the sensor needs to be turned on for 2. Heres a circuit that shows how I connected the MQ 3. I used a 1. 0K ohm load resistor in series with the sensor resistor. The MQ 3 datasheet says to use a 2. K ohm resistor, but anyone whos used this sensor knows that this constrains the measured voltage to a tight, high range. I recommend a 1. 0K ohm resistor. Make sure you connect all the grounds together. Arduino Breathalyzer Schematic. Its easy to read the analog value from the analog input pin with a very simple Arduino program. I chose to run the Standard Firmata firmware on the Arduino and run a Processing program on my computer to display the values. More on that later. And Now, Some Math. The good news is that if you know how much alcohol is in your breath, there is a straightforward formula used to calculate your blood alcohol content BAC. Alcohol content in a volume of breath or blood is expressed as mgL milligrams per liter. A 1 blood alcohol content is 1. L or 1. 0,0. 00mgL. Since this level would almost certainly be fatal, lets scale this down from dead to drunk. A 0. 1 BAC is 1. L. How does this relate to the breath It turns out that there is a standard conversion from breath alcohol content to BAC that is employed by commercial breathalyzers. Breath and blood alcohol content differ by a factor of 2. So, a person with BAC of 0. L of alcohol in their blood and 1. So, our final formula for calculating BAC from the alcohol measured in the breath is BAC breath mgL 0. Sensor Calibration Challenges. So, I simply need to use the sensor to determine how many mgL of alcohol there is in my breath, right The bad news is that it is very difficult to know how much alcohol is in your breath in terms of mgL The poorly written MQ 3 datasheet says to calibrate the sensor by exposing it to a known alcohol gas of 0. L. From there, you can determine gas alcohol content in terms of mgL. But how do I create an air environment with 0. L alcohol I could evaporate 0. I measure out exactly 0. I dont have a source of pure ethanol. I could buy 1. 51 proof Everclear grain alcohol but then would need to account for the different density when measuring this tiny quantity. And theres the additional complexity in that evaporating aqueous ethanol will alter the humidity, and the sensor readings are sensitive to humidity This is getting complicated. If were really motivated, I would drive to Wisconsin where I could buy 1. Everclear. Last time I drove to Wisconsin was to buy illegal fireworks, and it seems that my only reason for visiting Wisconsin is to purchase contraband and smuggle it back into Minnesota. But I digressthe bottom line is that calibration according to the MQ 3 datasheet is hard. Another calibration approach would be to use my breath as a known concentration of ethanol after drinking a known quantity of alcoholic beverages. I could drink the right amount of alcohol to give a 0. L concentraion in my breath and measure the resistance to get my calibration baseline. But this presents problems, tooThe sensor calibration depends on 0. L concentration in clean air. What is clean air I think it means air that is devoid of other contaminating gases that affect the sensor, and assumes 2. Those conditions are not going to be true in my breath My head is spinning, and I havent even started drinking yet. In short, I dont know how to create the right conditions for accurate calibration without a laboratory. Any ideas welcome. Forget Calibration Use Correlation. Ultimately, I decided to simply correlate sensor readings with computed BAC based on body weight, amount of alcohol consumed, and elapsed time. There are plenty of online charts and calculators that tell you your approximate BAC based on these inputs. Unfortunately, they dont give the same values for the same input I used the first link below from Viginia Tech because it was the source of the values cited in the Wikipedia BAC page and everything in Wikipedia is correct, rightStudentsalcohol. Effectsestimating. BACindex. htmhttp www. BAC calculator. asphttp health. My experimental approach is simply to drink alcohol, compute my BAC according to a chart, and correlate that value to the voltage reading from the Arduino analong input pin. If the sensor is accurate, and if I gather enough data points, I should be able to correlate measured voltage to BAC. This will involve a lot of drinking, night after night. Im doing this for science. Science Sensor Hardware. In order to ensure that I exposed the sensor to a uniform breath sample, I decided to enclose the sensor in a glass chamber. I used a simple glass jar with a plastic lid it used to hold spices. Small jar to serve as breath chamber. I drilled some holes in the lid and used some vinyl tubing as a tube to blow into. One small hole is for the sensor wires, and the other small hole is for breath to escape as I blow more breath into the jar. Plastic cap for base of breathalyzer chamber. MQ 3 sensor installed in breathalyzer chamber. In the blow tube, I added a tee joint so that condensation from my breath could drain out. I know thats gross, but the condensation builds up. I plugged the tee joint drain when I was blowing a breath sample.