Sinewave Direct Digital Synthesis Example Posted

Started by tkreyche February 12, 2005

After getting a great deal of good advice from the group, here's my
small contribution:

A simple example of how to use the LPC2138 to create a sine wave
using direct digital synthesis (DDS).

It was developed for the Keil LPC2138 board and compiler and puts out
an audio tone from the DAC using the amplifier on the board. It
should work for other boards as well.

It's amazingly simple to create very nice looking sine waves using
DDS on the LPC2138. The waves can easily be frequency modulated or
amplitude modulated, and you can create musical chords by combining
multiple sine waves.

I included a couple technical documents that explain the process in
detail--as a result there are relatively few comments in the source
code.

Tom Kreyche




Re: Sinewave Direct Digital Synthesis Example Posted
Re: Sinewave Direct Digital Synthesis Example Posted

An Engineer's Guide to the LPC2100 Series


Sorry, I forgot to mention it's in the "DDS" folder in the file
section. --- In , "tkreyche" <tkreyche@w...> wrote:
>
> After getting a great deal of good advice from the group, here's my
> small contribution:
>
> A simple example of how to use the LPC2138 to create a sine wave
> using direct digital synthesis (DDS).
>
> It was developed for the Keil LPC2138 board and compiler and puts
out
> an audio tone from the DAC using the amplifier on the board. It
> should work for other boards as well.
>
> It's amazingly simple to create very nice looking sine waves using
> DDS on the LPC2138. The waves can easily be frequency modulated or
> amplitude modulated, and you can create musical chords by combining
> multiple sine waves.
>
> I included a couple technical documents that explain the process in
> detail--as a result there are relatively few comments in the source
> code.
>
> Tom Kreyche



----- Original Message -----
From: "tkreyche" <>
To: <>
Sent: Saturday, February 12, 2005 11:42 PM
Subject: [lpc2000] Sinewave Direct Digital Synthesis Example Posted >
>
> After getting a great deal of good advice from the group, here's my
> small contribution:
>
> A simple example of how to use the LPC2138 to create a sine wave
> using direct digital synthesis (DDS).
>
> It was developed for the Keil LPC2138 board and compiler and puts out
> an audio tone from the DAC using the amplifier on the board. It
> should work for other boards as well.
>
> It's amazingly simple to create very nice looking sine waves using
> DDS on the LPC2138. The waves can easily be frequency modulated or
> amplitude modulated, and you can create musical chords by combining
> multiple sine waves.
>
> I included a couple technical documents that explain the process in
> detail--as a result there are relatively few comments in the source
> code.

I did something similar some time ago with the LPC2106, with an AD557 DAC.
That was when I found the limitation on the GPIO speed, I couldn't generate
a higher frequency than I could with an AVR.

Leon
--



> I did something similar some time ago with the LPC2106, with an
AD557 DAC.
> That was when I found the limitation on the GPIO speed, I couldn't
generate
> a higher frequency than I could with an AVR.
>
> Leon


Well, you're sure not going to implement a GHz digital radio, but
it's fine for audio frequencies. I needed a fancy tone generator for
a project -- it turns out to be damn near impossible to get the chip
vendors who make melody ICs for cell phones to sell them in small
quantities.

So for $5 the LPC2132 works well for audio (and you can play .wav
files too). If you slow it down the current is < 10 mA.

Tom