Arduino Waveform Generator

Waveform generators (also called function generators) are useful for testing and debugging circuits.  I often use them to test the frequency response of electronics components like op amp and sensors.  This waveform generator is powered by an Arduino.  It outputs four waveshapes: sine, triangle, pulse, and saw, each waveshape ranges in frequency from 1Hz-50kHz.  The frequency, pulse width, and overall amplitude (gain) of the waveforms is controlled by three potentiometers.  I've also included (optional) indicator LEDs that let you know which type of wave is currently being sent to the output.

Parts List:

(4x) Mini SPST 1.5-Amp Momentary Pushbutton Switch (2 packages) Radioshack #275-1556
(8x) 10K Ohm 1/4-Watt Carbon Film Resistor  (2 packages) Radioshack #271-1335
(9x) 20K Ohm 1/4-Watt Carbon Film Resistor (2 packages)
(1x) 50K-Ohm Linear-Taper Potentiometer Radioshack #271-1716
(1x) 10K-Omh Audio-Taper Potentiometer Radioshack #271-1721
(1x) 10K-Ohm Audio Control Potentiometer with SPST Switch Radioshack #271-215
(1x) 1/8" Stereo In-Line Audio Jack Radioshack #274-274
(1x) 10.01µf 50V Ceramic Disc Capacitor Radioshack #55047551
(1x) 4.7K Ohm 1/4-Watt Carbon Film Resistor Radioshack #271-1330
(1x) 8 Pin Socket Radioshack #276-1995
(1x) LM386 Low Voltage Audio Power Amplifier Radioshack #276-1731
(2x) 220µF 35V 20% Radial-lead Electrolytic Capacitor (or anything between 200 and 300 uF) Radioshack #272-1029
(1x) Arduino Uno REV 3 Radioshack #276-128
(1x) Arduino Proto Shield Radioshack #276-140
(4x) White Super-bright LED Indicator Radioshack #55050633
(4x) 740 ohm 1/4W 5% Carbon Film Resistor (1 package) Radioshack 271-1317
(1x) 300Ohm resistor


Additional Materials:

Heat Shrink Radioshack #278-1611
22 Gauge Wire Radioshack #278-1224
Solder Radioshack #64-013
Drill
Hot Glue
Glue
Black diffusor material (tissue paper, plastic, etc)

Step 1: Prepare Arduino Proto Shield

The Arduino Proto Shields are a convenient way to attach circuits to an Arduino, but I like to trim them down a little bit first so they do not take up so much room in the project enclosure.   Start by trimming the pins down with a pair of wire cutters.  Next, cut off the six pin socket.  Finally, cut the sockets from the top of the board.

Comments

[dripberger]

Hi, is the 50kOhm pot for PWM or frequency?

[TeslaRox]

How can one make this able to drive a flyback transformer. I know there is a way to do it, a vid of a guy on youtube does it but doesn't show how. I ordered a DDS function generator and just cant put 2 and 2 together to figure out how to drive a flyback with it and I would like to be past this.. simple set back.

[randomnonsense11]

This may seem a bit elementary, but what is the use of this?

[amandaghassaei]

lots of things, mostly testing the frequency response of circuits, response time of components... something like this:
http://www.instructables.com/id/Oscilloscope-How-To/step9/Advanced-Oscilloscope-Dual-Channel-Measurements/
anything you would need an oscillating signal to measure.

[amandaghassaei]

you could also send it to speakers to make sounds or patch it into some other audio effects- what I plan on doing with it.

[janw]

It is a very nice project but its a bit overkill to use an arduino for a functiongenerator that will be patched in a soundgenerating system (aka a synth.)

Even if you would use a microcontroller, an attiny would be a better choice I guess (you can use your arduino to program these).

On the other hand, if you go a bit bigger and use an atmega32 you could make an entire synth with it. Have a look at the Meeblip website (meeblip.com)

[flashular]

I hope not to detract from this great instructable, but if you want an arduino based audio synth you might also consider the GinSing shield ( www.ginsingsound.com ).

[veden]

great work !! i was wondering to make arduino read a sine wave from 12VAC transformer. i want to get data every sample that been generated..can i give me idea..can u guide me pls

[amandaghassaei]

maybe something like this:
http://www.instructables.com/id/Arduino-Audio-Input/

[rgabriel3]

Hi Amanda,
Why you choose 20000 values on the sin function? and why the sample rate is 10000?
Thanks =]

[amandaghassaei]

the numbers actually aren't related. I chose 20000 values for the sin function bc I could fit that many numbers in the Arduino's memory and it helps to increase the resolution of the signal. I chose the 100kHz sampling rate so that I could easily reproduce signals through the audible range (~20hz to 20kHz). at 100kHz sampling rate, I can get 100/20 = 5 samples per cycle on a 20kHz signal.

[Panichou]

Hi Amanda.
Is there a simple way to generate a sin wave from the arduino ?
I want to have a signal which contains two or three frequencies. I thought about generating a few sin wave with the arduino then multiply or sum them.

Thank you

[amandaghassaei]

yes there is code in this ible to help you do that:
http://www.instructables.com/id/Arduino-Audio-Output/

[eran]

Hi Amanada.
thanks for writing so many wonderful tutorials, its a pleasure following your tutorials, they are clear, and well thought of!
I am building a game for kids with which we can demonstrate breaking glass in classroom.
I wanted to know if you can add directions on how to create a sine wave with a resolution of 1/10 Hz - for example ,I need to be able to tune the generator to 1000.03 Hz. should I use a second potentiometer to get better resolution? and in the Arduino code itself, what should needs to be change for the sine wave section?

thanks,

Eran

[amandaghassaei]

you need to change this line:
frequency = freqCurrent;//new frequency- number between 0 and 1024
freqscaled = 48*frequency+1;//from 1 to ~50,000
get it so that freqscaled is in the range you want, maybe 999 to 10001Hz for values of frequency that range from 0 to 1024
also change:
int frequency;
int freqCurrent;
unsigned int freqscaled;
to
float frequency;
float freqCurrent;
float freqscaled;
that should work, let me know if you have trouble

[tisla]

:( need some help...

im using an arduino clone. how should i connect the components to the micro controller? should i wire the PD,PB,PC to its PB, PB, PC counter part using the schematic of the clone? TIA

:(

[amandaghassaei]

yes, you should be able to find the pin connections here:
http://arduino.cc/en/Hacking/PinMapping168

[tisla]

hi amanda, can i use the code directly to an arduino clone? atmega328 base? tia

[amandaghassaei]

yes that's fine

[mausi_mick]

hi Amanda,

it's a wonderfull project !

i have one question:

Is the resistance (R21) between ground and the r2r-ladder 10k or 20 k.
In the schematic it is 20k, but in the description it is 10k.
I don't know, what' right ,

thanks

[amandaghassaei]

it's 20, sorry about that
http://en.wikipedia.org/wiki/Resistor_ladder

[_SarahC_]

How did you get the values from the python script stored, then output to the Arduino's memory to store them?

Ah - you're writing a string - and you copy and paste that into your Arduino script?

sine20000[] = [copy & pasted python output here]

[amandaghassaei]

exactly

[BEYERdinamic]

you know if you can climb up to 5MHz frequency?

[KKHausman]

The Arduino's own processor limits the maximum step speed, which constrains the wave frequency. The Arduino's processor frequency internally is 8MHz, while the on-board 16MHz oscillator allows each step to occur at the faster rate. If a full wave takes 16 steps, then the maximum frequency of the output (ideal) would be 1MHz but resolution of the waveform would suffer. In the provided sketch, the triangular waveform is stored in an array using (127+127) increments per cycle, so the maximum (ideal) frequency would be roughly 125kHz. In addition, the low pass filter that smooths out the wave output also constrains the operating frequency based on the discharge rate of the cap, so that the provided cap and resistor values operate under 100kHz..

[jleguizamo rojas]

ok, so I only need change the ports right?

[amandaghassaei]

yes, do you know how? I think you will also have to change the timer setup.

[jleguizamo rojas]

Can I make this proyect with an Arduino Mega?

[amandaghassaei]

Yes, but the code and pin connections will change.

[BEYERdinamic]

tu sabes si se puede subir la frecuencia hasta los 5MHz?

[jher-se]

Hi Amanda.! it's exelent you project .. I just wanna know, where I can find the full schematic.. Do you think that can help me with that ?
thank you very much..

[amandaghassaei]

thanks! the schematic is on the first step.

[mkahata]

amanda. it is so nice instruction. i was looking interrupt for Arduino few month. but not easy to find good instruction. your's is best. thank you. i put this interrupt function to my open hardware brain wave interface project. works nice. but can not do many things in the main loop and inside of interrupt anyway. mean can not set sampling frequency to high. but that is ok for usually. also can not use Analogue write function. can use hardware interrupt then can use Analogue write but processing time problem is same. specially analog read takes time. currently processing to make document for my project. let you know then.

[amandaghassaei]

great, can't wait to see it!

[CenterChannelSpeaker]

This is right up my alley

[Shonswer]

I was looking a project for my electronic subject, i will try this, thanks for tutorial

[mauricio 1995]

mi caso es que estoy recién empezando en esto de la electrónica tengo 17 años mi pregunta o mas bien petición es si puedes mandarme el diseño de las placas y también una recomendación de con que programa puedo simularlo

[amandaghassaei]

http://www.instructables.com/id/Arduino-Waveform-Generator/step2/Enclosure/

[dexterandrada]

Great Job!

You can actually sell some of these for people that might be interested of building one but doesn't have the time. This has many wonderful uses really!

A DIY tester is the way to go!

[wgrube]

Nice work! Very detailed and well executed! I think I'm gonna build this...