15
votes
Accepted
Does ADC conversion to a voltage rely on the actual value of the +5 V pin?
The ADC inside the Arduino does not measure voltage, but rather a
voltage ratio. Namely the ratio from the voltage at the analog input
to the voltage at the Vref pin.
In the default configuration, ...
- 43.9k
11
votes
Accepted
Why analogue pins affect each other?
This is to be expected.
The other pins have nothing connected to it, so their voltage is floating.
The Arduino MCU only has a single ADC. To read the different analog pins, it uses a multiplexer to ...
- 11.3k
11
votes
What is the most efficient voltage divider for Arduino?
The most efficient is not to have a voltage divider at all. Or at least to only have a voltage divider when you actually need one.
My preferred schematic is this:
simulate this circuit – ...
- 105k
11
votes
Accepted
Analog read not working while using WiFi
The ESP32 has two ADCs. One of them, ADC2, is actively used by the WiFi.
From the IDF documentation:
Since the ADC2 module is also used by the Wi-Fi, only one of them could get the preemption when ...
- 105k
9
votes
Does ADC conversion to a voltage rely on the actual value of the +5 V pin?
A USB-powered Arduino Nano will have an ADC voltage reference which can't be relied on, due to the +/- 5% tolerance of the incoming USB voltage. On top of that, the Nano has an MBR0520 Schottky diode (...
- 2,114
9
votes
what is arduino adc reference?
The AD converter in the ATMega microcontroller (as used in Arduino) converts an input voltage to a number.
This ADC happens to be 10 bit that means 2^10 states which is 1024.
The number 0 (zero) ...
- 191
8
votes
A question about resistance measurement with arduino
If you know Ohm's Law (which you should) and you realise that the ADC measures voltage, you should be able to work it out from there. But I will go into minute detail for you to ensure you understand.
...
- 105k
7
votes
Accepted
How can I create a battery level circuit
Firstly, if I understand your schematic right, you're not "dividing" anything there. If the ringed red symbol is where you are connecting the ADC then either you will see near 4V on there (if it's ...
- 105k
6
votes
Uno - measure the voltage, NOT connecting GND
If I understand the description correctly, neither side of the resistor is at ground potential. There's a wide gamut of methods of dealing with this, for example using a differential ADC unit, or ...
- 8,870
6
votes
How to measure the supply voltage of Arduino without using an analog pin
Yes, you can do it.
You can measure the voltage of the internal (approximately) 1.1V reference voltage using the ADC and use the results of that to calculate what the reference voltage you used (VCC) ...
- 105k
6
votes
Accepted
Is it possible to measure analog output?
First: Why would you need to measure the PWM value. You already know it; it's saved in the val variable. Why not just use this variable for later use in code?
Second: Doing the analogRead on the same ...
- 16.5k
6
votes
Accepted
Can I test if something is connected to analog pin?
The input stage of the analog-to-digital converter is a sample-and-hold
capacitor. When you take an analog reading, the capacitor is connected
to the input pin, it is charged to the voltage you want ...
- 43.9k
5
votes
Arduino unstable analog reading when using power supply
I solved a similar issue by adding a pin from supply to AREF and it's now stable. This fixed a frustrating pH meter issue on my Mega that every time I plugged USB in it would be right, but as soon as ...
- 51
5
votes
AnalogRead value constant for a varying voltage (for LED brightness variation)
As CrossRoads says, there really isn't any such thing as analog output on an Arduino. (Any Arduino unless it has a built-in DAC.) It uses pulse-width modulation to vary the "duty cycle" of the output ...
- 5,702
5
votes
Accepted
ADC register always returning high
First, let me give a couple of suggestions on the programming style.
There is no point in defining your own variables for accessing the
hardware registers: the avr-libc does that for you, you just ...
- 43.9k
4
votes
Can I connect a PWM pin on one Arduino to an analog input on another?
For greater precision, less code, faster execution and no need for capacitors read the PWM "analog" signal on the other Arduino from a digital input pin with
pulseIn(pin, HIGH, timeout)
The timeout ...
4
votes
Accepted
10 bit PWM on Arduino UNO
On your code, you using analogRead but declaring the pin (A3) as output. Change it to pinMode(A3,INPUT);
Aside from that, PWM is basically a digital output which changing (HIGH and LOW) at specified ...
- 1,258
4
votes
Accepted
Not getting proper readings on Arduino from MAP Sensor
The ground does need to be connected. I have also added a RC filter to stabilize the sensor reading.
Connection :
Arduino 5V ----> MAP Vcc
Arduino GND ----> MAP GND
Arduino Analog Pin A0 <--...
- 1,486
4
votes
Accepted
What is the definition of these arduino commands, and how do they affect the circuit?
These are a lot of different questions. However, you can find most of the Arduino related answers in the official reference:
Arduino reference Guide
Some other answers:
how to declare variables:
...
- 13k
4
votes
Accepted
Analog thermistor readings are wrong
One possibility that has not been mentioned yet: the issue may be
the calibration of your ADC converter. Your code carries the implicit
assumption that the voltage you measure is
V = Vref × RawADC ÷ ...
- 43.9k
4
votes
Accepted
Arduino continuously reading ADC value using interrupt
reset the resultNumber to 0 after you have written it to serial. and turn interrupts back on
void loop () {
while (resultNumber < MAX_RESULTS)
{ }
for (int i = 0; i < MAX_RESULTS; i++)...
- 3,267
4
votes
Lowest voltage applicable on AREF pin on Uno and Mega
According to the datasheet (page 375) the minimum voltage you are allowed to have as a reference voltage for the ADC is 1V.
- 105k
4
votes
Accepted
Arduino UNO - analogRead() returning mixed results
The analogWrite function, despite its name, outputs PWM (pulse width modulation) which is either fully on or fully off, with varying duty cycles. If you run that through a RC network (eg. 4.7k in ...
- 38.5k
4
votes
Accepted
How can I differentiate between multiple circuits?
First, let's consider the logic of your program. You have two groups of
pins: 6 pins connected to the wires and 6 pins connected to
the terminals. The first thing I would do is forget that ...
- 43.9k
4
votes
Accepted
How to boil down analog input to just three cases?
The simplest fix to your problem is to change the map() call to
byte alrmSet = map(alrmSwState, 0, 1024, 0, 3);
In the call above, the mapped intervals are of the semi-open type, e.g.
[a, b), ...
- 43.9k
4
votes
How to convert digital signal to analog value
The problem seems to be clear to you: for slow systems a pwm signal can be considered analog, but measuring at higher rates and without a filter reveales the digital nature behind pwm and all you see ...
- 1,869
4
votes
Accepted
Noise on piezo analog read due to Arduino power supply
The 9V wall adapter is in most cases a switched power regulator with a high frequency. That's like a radio transmitter direct beside the wire. So there is nothing mystical, when the smooth USB Voltage ...
- 1,893
4
votes
Arduino measuring high-voltage electric fence
You are talking about measuring 2 to 10 kV pulses, with about 1 to 5 J of energy per pulse.
The maximum current may be very low, but the voltages you want to measure are very high, and will very ...
- 1,795
4
votes
Inaccurate voltage readings on an esp32 as opposed to multimeter
I see multiple problems with your setup:
You only take a measurement every 100ms. That measurement takes the voltage during a very short time span. But the lowest string on a guitar in standard ...
- 16.5k
3
votes
Cheapest and easiest Arduino board for 12 bit ADC, thinking of M0
Use a Teensy 3.x. Those have 13 bit ADCs
- 11.3k
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