Start • Progress
in Digital Audio • Digital
Audio Processing • Digital
Media Basics • Audio
Player Project • System
Timing Analysis • Hardware • SD
Card Interface • Audio
DAC Interface • 24-Minute
I2S Interface • Software • Half
Empty • Cards
on the Table • Face
the Music • Sources
and PDF
AUDIO
PLAYER PROJECT
My
audio player is an embedded hardware/software
solution for 16-bit digital audio. The purpose
of the project is to achieve CD-quality audio,
which means 16 bits (96 dB dynamic range) and
a sampling rate of at least 44.1 kHz. If lower
quality is satisfactory, you can use a simpler
option. For example, you can use the onboard
DAC (10-bit resolution and a maximum speed of
1 µs).
This
project has three major functional blocks: a
microcontroller, an SD card interface, and an
audio DAC interface. The prototype is built
around an LPC2148 evaluation board from Olimex
and two extra prototype boards: one for audio
DAC and one for the SD card (see Photo 1 and
Figure 2, p. 42). Later on, I decided to integrate
everything into one board to be a module/building
block for use in embedded systems.
(Click
here to enlarge) |
Photo
1—The prototype is built around an Olimex
LPC2148 board. I added two extra prototype
boards. One is for the SD card interface.
The other is for the Texas Instruments audio
DAC. |
(Click
here to enlarge) |
Figure
2—The system’s main board is a modified
Olimex LPC2148 evaluation board. Two alternative
audio DAC circuits are shown. Use one of
them or your own. The SD card interface
is a standard SPI mode |
