Correcting Waveform Centre

Using Arduino Audio
1

Hi All,

This is my first post, so first let me start by saying hello, and thanks in advance for any help.

My problem is, I am very new to arduino and I have created a simple DDS signal using my Arduino Uno, the signal works great and it currently connected to a cheap 0.5w speaker.

However, as all of my DDS reference values range from 0-255, and because my speakers ground is 0v. I assume that my waveform is positive only (and not very healthy for the speaker).

I would like to centre the AC/waveform around 0v, can anyone recommend an op-amp circuit that would achieve this (op-amps are not my strong point).

Thanks for any help.
James

2

Scale your DDS around 128, with positive +127 and negative -127. Than put a cap to eliminate DC offset, about 2.5V

3

You add 127 to all the values going to analogue write.
You did not mention analogue write in your original question.

4

A capicitor shifts the referance. An arduino can o ly supply voltages between it's rails directly but there is no reasion to have the gignal ground and the analogue ground at the same level.

5

Dodo that the arduino would have to handle voltages below its ground potential and it can not do that.
Welcome to the real world.