35
votes
Accepted
What is the frequency of PWM output on Arduino
The PWM signal is generated by timers on the AVR chips. Each timer can generate a PWM signal on two or three different pins. Each pin can have it's own duty cycle, but they share the PWM frequency. ...
- 1,343
19
votes
Accepted
Is it possible to generate an exact 15 kHz clock pulse using an Arduino?
You can get pretty close if you program Timer 1 directly (not
through the library), and have it run with the prescaler set to 1.
Ideally, you want the period of the timer in clock cycles to be:
F_CPU /...
- 35.5k
16
votes
Accepted
Increase PWM bit resolution
The Arduino Uno is based on an ATmega382P microcontroller. This chip has
two 8-bit timers, driving two PWM channels each, and one 16-bit timer,
driving the last two channels.
You cannot increase the ...
- 35.5k
13
votes
Accepted
Why do I get negative voltages for a PWM waveform?
At first you had the scope AC (Alternating Current) coupled. Then you switched it to DC (Direct Current) coupled.
AC coupling is used to remove the DC component of a signal. It places a large ...
- 6,451
13
votes
Accepted
How to output a true analog voltage at output pin
You basically have three options:
Switch to an Arduino Due which has a built-in DAC which outputs a real voltage.
Add an external DAC chip (such as the MCP4821/2) to create the voltage for you
Use a ...
- 101k
12
votes
Set PWM frequency to 25 kHz
You can configure Timer 1 to cycle at 25 kHz in phase correct PWM mode, and use it's two outputs on pins 9 and 10 like so:
// PWM output @ 25 kHz, only on pins 9 and 10.
// Output value should be ...
- 35.5k
12
votes
Accepted
Set PWM frequency to 25 kHz
I am posting this second answer since I realized it is possible to have
4 PWM channels at 25 kHz with 161 steps on a single Arduino Uno. This
involves changing the main clock frequency to 8 MHz, ...
- 35.5k
11
votes
Accepted
ArduinoUNO/MEGA, Is there a way to exceed 256 in analogWrite
Section 16, "16-bit Timer/Counter1 with PWM" of Atmel-8271J-AVR- ATmega-Datasheet_11/2015 describes using Timer/Counter-1 for 16-bit PWM, including sample code in both C and assembler. It might take a ...
- 14.4k
9
votes
Accepted
Arduino PWM malfunctioning
Pin 11 is shared between both PWM and SPI. By activating SPI you've disabled PWM from working on that pin. Either use another PWM pin instead, or switch to software SPI on different pins.
- 17.5k
9
votes
ArduinoUNO/MEGA, Is there a way to exceed 256 in analogWrite
The simplest way is to change your value range to 0-255. You can't change analogWrite's range, since that is fixed in the core software.
analogWrite(5, val >> 2);
The >> 2 bit-shifts the ...
- 101k
9
votes
Is it possible to generate an exact 15 kHz clock pulse using an Arduino?
Since the timer1 library only accepts whole numbers for the µs parameter you get a error. You could skip using the library and configure the timer directly. Or you could have a look at the source code ...
- 11.1k
8
votes
attiny85 and arduino - analogRead + pwmOut
Analog read is 10-bits (2^10 = 0-1023 range), analog write is 8-bits (2^8 = 0-255 range). Ditch the lower two bits of the result either by doing:
analogIn = analogIn >> 2;
which can be ...
- 5,170
8
votes
Accepted
PWM signaling with Arduinos: What is the reason for the ground connection?
Is PWM really a signal? To me, it looks like an electric current turned on and kept on for a certain time, then off for a while repeatedly. What makes this a "signal"?
At the most basic, it is a ...
- 17.5k
7
votes
Accepted
Does the square-wave nature of PWM dictate how much resistance you need?
It's... mostly wrong. For three independent reasons.
The LEDs themselves, like all diodes, absorb some of the electrovoltaic potential of the electricity passing through them, resulting in a voltage ...
- 17.5k
7
votes
Accepted
Can I connect a PWM pin on one Arduino to an analog input on another?
Yes, you can do this with "a little programming" or more easily by adding two cheap components.
If you connect a say 47k resistor from PWM_Out to Analog_In and a say 100 uF capacitor from Anaolg_In ...
- 2,411
7
votes
How to output a true analog voltage at output pin
At 5V, a 1 ohm resistor will try to sink 1A and far exceed the 40mA specs. Please use at least a 5/0.040=125 ohm resistor to protect your pin. And if you put the a capacitor between your resistor ...
- 2,292
7
votes
Accepted
How do you get 2 PWM pins to inversely bitbang at 25 KHz on a Nano?
There are various solutions. I suggest using two PWM channels driven by
a single timer. This way you do not have to worry about synchronizing
two timers. You can configure the channels identically, ...
- 35.5k
6
votes
Accepted
Use Arduino's PWM to control motor direction?
You seem to have misunderstood PWM here. It's actually a digital signal which is constantly pulsing on and off very quickly (several hundred times per second). You don't actually change the output ...
- 10.8k
6
votes
Accepted
Arduino LED backlight - should PWM be used with transistor or capacitor?
You don't need the MOSFET, you don't need the capacitor, you do need the resistor.
The pins on your Arduino can deliver up to 20mA comfortably, so in this case there is no need for the MOSFET. ...
- 464
6
votes
Accepted
Does millis() conflict with the PWM pins associated with timer 0?
They do not conflict as millis() strictly reads the immediate value in TCNT0 whereas PWM via timer 0 uses the hardware's ability to compare the value of TCNT0 with the values in OCR0x without ...
- 17.5k
6
votes
Accepted
Why does an RGB LED between VCC and PWM work?
This is a common arrangement and is known as Common Anode, and the I/O pin is said to be sinking current.
To better understand what is happening here it's best to think of an I/O pin as a two-...
- 101k
6
votes
How do I set a 25 kHz PWM signal on an ESP-WROOM-32?
It is very simple to set up a PWM signal at any frequency you desire, with any resolution you desire, provided you don't exceed the maximum 'bandwidth': the frequency multplied by the resolution must ...
- 1,389
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 ...
- 13.7k
6
votes
How do I convert 0-5v PWM to a 0-12v PWM
I advice you to learn about basics of how to connect external components to MCU.
Anwser to your question is simple transistor amplifier... So you can use bipolar transistor (NPN/PNP) or MOSFET... ...
- 151
6
votes
Is it possible to generate an exact 15 kHz clock pulse using an Arduino?
A better way to do the above average 15 kHz (or any other frequency) is with a phase accumulator scheme. There are no IF tests; on each tick of an interrupt, you add a step to an accumulator and ...
- 595
6
votes
Can’t set duty cycle to 0% with custom PWM
That is how it is supposed to be. In this fast PWM mode, the duty cycle
is (OCR1A+1)/(ICR1+1). If you want a duty cycle of zero, you have to
disengage the PWM and turn the pin to OUTPUT LOW.
This is ...
- 35.5k
5
votes
Does millis() conflict with the PWM pins associated with timer 0?
Just to add to @Ignacio's answer which has directly answered your question. The "conflict" you speak of is in relation to Timer0's prescaler.
For the most part, you can use those pins (incidentally ...
- 1,302
5
votes
Accepted
Arduino PWM fading led
From your code you are using Timer0 in FastPWM mode with top = 0xFF.
In this mode, as used in your code, OCR0A defines the pulse width rate (more precisely, OCR0A / 256).
Timer0 uses port OC0A and ...
- 8,809
5
votes
Accepted
How can the Arduino Uno support up to 12 servos if it only has 6 digital PWM pins?
Although I haven't looked at the source myself, in these types of situations they usually use interrupt timer 1, which in PWM mode would have been associated with pins 9 and 10. This would explain why ...
- 6,067
5
votes
Can I connect a PWM pin on one Arduino to an analog input on another?
It is possible, but not the best idea. The analog inputs require a reasonably stable input - this can be achieved with a RC filter to smooth the PWM output. This would work for reasonably slow data ...
- 1,635
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