I have tried measuring the analog pin value using the provided standard sketch in the Arduino IDE. However even when there is no connection to the pin, it prints out random values. Is there anything that has to be taken care of?
I have a FSR sensor connected from 5V+ to analog pin 0
No connection giving you random value is completely expected. The pin is floating, and may or may not have a charge on it at any time, giving random values.
Attach the analog input to ground - it should return a number approaching zero (within the accuracy and noise of the ADC).
You have to use "Pull-up" or "Pull-down" resistor. Read here about this circuit: http://www.ladyada.net/learn/arduino/lesson5.html
Providing a path of higher resistance to ground ensures that when that portion of the circuit is open, the static electricity remaining in the portion connected to the pin gets grounded. It also splits the voltage between both paths to allow you to properly throttle the voltage to the pin.
The same problem arise to me ,
What you have to do is change the" Serial.begin(9600);"
To "Serial.beigin(115200);
Now it is showing exact zeroes without any input source.
Related
Im currently trying to get an electric signal from arduino, its 5v and 1amp that i get from a powersupply.
I want to input that signal into an arduino pin, lets say pin 4.
The main powersource from my arduino is via usb, but the 5v signal is from an external device.
I just want to know the number of time that signal became active, like a switch.
As far as i know arduino can take only .04amp from 5v.
Is there anyway i can reduce the current?
Anyway to obtain the value of a resistor to make it less dangerous for my arduino?
Your question is a very common application for Arduino!
You can give your Arduino some additional protection by placing a 10kOhm resistor between the Arduino analog pin you wish to use and the positive voltage output of the power supply.
If you're worried that the voltage could increase above 5V, you can protect your arduino with a simple voltage divider using two resistors. There's a detailed tutorial for this approach here: https://startingelectronics.org/articles/arduino/measuring-voltage-with-arduino/ Here's a simplified circuit diagram with a voltage divider that reduces voltage 11 fold - making voltages up to 55V safe to measure (where the battery could be replaced by your power supply):
For your code, you can use analogread() to read the voltage of the pin. If you wired it correctly, it should return near 0 when the powersupply is at 0, and 1026 or thereabouts if it is at 5v (or whatever the maximum value your voltage divider is designed for). Here is an example to get you started :
https://www.arduino.cc/reference/en/language/functions/analog-io/analogread/
If you need any support with your code to count the number of times the voltage goes high, post that as a separate question along with the code you have so far.
I am using 6 different sensors which are working simultaneously, but I got a problem in the readings from LM35 temperature sensor and MQ-7 Carbon Monoxide sensor. The values are changing depending on the power source.
How can I fix this problem? I'm planning to use a Sony power bank to feed my system but I am getting the wrong values especially from the temperature sensor.
Make sure that your power source is stable and continuous (i.e. make sure that your power bank is working fine and check its current output if its compatible with Arduino)
Make sure that your sensors are wired correct and working fine, try with different LM35 and MQ-7 sensors, if you have that chance.
Make sure that you are supplying your circuit with correct voltage and current, sensors may work unstable if you are supplying them directly from Arduino pins (because maximum current limit of the pins onboard may not be enough for your circuit), try an external power source such as MB102 power module.
Although, it's not a coding problem my suggestion is you can use signal conditioning to solved this. Search about low pass filter and high pass filter to filtering frequency in output sensor.
The simple method is using voltage divider, like this:
Vout = (R1/R1+R2) * Vin
R1 is your sensor, and R2 is resistor.
I would like to know if there is any way to display the battery level of an arduino running off a rechargeable battery. Is there some piece of equipment or certain code I could use with an LCD? To be clear I'm looking to display the battery percentage not the voltage.
I'm using an adafruit proto board with a servo shield
Thanks in advance.
I don't know why you are avoiding the simple solution (resistor bridge into an analog input). Create a map in EEPROM to act as an interpolation table and re-scale it occasionally. Taking the voltage from that analog input and mapping it through your interpolation table will give you a percentage battery remaining for the LCD. (most batteries I have interacted with slowly decrease in output voltage as their percentage remaining drops and the slope/ curve is usually fairly repeatable)
i am using arduino uno , atmega328.
on analogRead on the analog pin A0 returns 0 when it is grounded, and with HIGH signal from another pin it returns some value around 1000. But when i connect it to a sensor which gives out around 26 mV it returns random values ...
YYY
My code is very basic, uses analogRead and display it in serial monitor.
A signal with fluctuations of 10mV is not random. The flucatuations are called noise. The standard approach is to add a low pass filter in hardware or software. Since you have a controller anyway I would go for software based low pass filtering. A simple and computational cheap but effective low pass filter is an exponential filter, also known as exponential moving average.
I am a CS guy getting started with Arduino. This is probably a very basic electronics question but from going over the arduino tutorials everything is connected to the arduino with a resistor.
Well since i am following the tutorials i know what type of resistor i should use but what i do not know is why i should use one? and What type of resistor to pick i am to do something which is not covered in a tutorial.
The resistor simply serves to limit the current into or out of a pin in case something goes awry. If your AVR decides to output high on a pin that something else wants low (or vice-versa), large, damaging currents can occur if not limited by some resistance. The current limit for AVRs is about 20 milliamps, and given that the voltages are usually 5V, something larger than 250 ohms "would work".
To give a margin of safety, 1-10k is a great choice; for digital signals it seldom matters unless you're into very high-speed applications (beyond the AVRs capability anyways). For analog inputs, a similar resistor would also be advisable, as the amount of current the ADC takes to sample is negligible when your resistor is in the few kilo-ohm range.
The underlying principle that you want to learn is Ohm's Law, which describes the relationship between voltage, resistance, and current in a circuit.
Resistors are used to
limit current,
devide voltage
protect against over voltage
pull-up, pull down
current to voltage conversion
etc ...
1) limit output current, the absolute max current per IO is 40mA, a typical LED works on ±2V 20mA.
the resistance value can by calculated by (5V - 2V)/(0.02A)=150Ω usually a 220Ω resistor is used, because: it consumes less power, there doesn't flow 20 milliamps, and there is no notable difference in emitted light.
2) if you have a analog voltage that variates between 0 and 10 Volts, you 'll need a voltage divider of 1/2. pick by example z2 10k and calculate z1 by 10k*(Vin,max/5V -1). take a value of resistance higher than the original calculated. and recalculate the new Vout.
3) place a resistor of 10k in series between the analog input of the arduino and the 'to measure voltage'
3) if you have to measure a analog current, you place a resistor to ground and the analog input, calculate the resistor by Z=5V/amps.
4) if you connect a button to the arduino, you 'll need to place a pull up or a pull down resistor. if you 're not using a resistor, the input is floating and can take any value (high or low). or you can enable the internal weak pull up. by pinMode(xx,INPUT); digitalWrite(xx,HIGH);. and disabeling by digitalWrite(xx,LOW); by default the pull-up is disabled.