Rainbow Electronics AT89C51SND1C - Manual (Page 73)

73
AT8xC51SND1C
4109E–8051–06/03
Audio Output
Interface
The AT8xC51SND1C implement an audio output interface allowing the audio bitstream
to be output in various formats. It is compatible with right and left justification PCM and
I
2 S formats and thanks to the on-chip PLL (see Section “Clock Controller”, page 12)
allows connection of almost all of the commercial audio DAC families available on the
market.
The audio bitstream can be from 2 different types:
• The MP3 decoded bitstream coming from the MP3 decoder for playing songs.
• The audio bitstream coming from the MCU for outputting voice or sounds.
Description The C51 core interfaces to the audio interface through five special function registers:
AUDCON0 and AUDCON1, the Audio Control registers (see Table 84 and Table 85);
AUDSTA, the Audio Status register (see Table 86); AUDDAT, the Audio Data register
(see Table 87); and AUDCLK, the Audio Clock Divider register (see Table 88).
Figure 48 shows the audio interface block diagram, blocks are detailed in the following
sections.
Figure 48. Audio Interface Block Diagram
AUD
CLOCK
UDRN
AUDSTA.6
0
1
DSIZ
AUDCON0.1
DSEL
Clock Generator
DCLK
DOUT
SCLK
JUST4:0
AUDCON0.7:3
POL
AUDCON0.2
AUDEN
AUDCON1.0
HLR
AUDCON0.0
0
1
SRC
AUDCON1.7
8
Data Converter
Audio Data
From C51
Audio Data
From MP3
DUP1:0
AUDCON1.2:1
16
16
SREQ
AUDSTA.7
Audio Buffer
AUBUSY
AUDSTA.5
Data Ready
DRQEN
AUDCON1.6
MP3 Buffer
Decoder
16
Sample
Request To
MP3 Decoder
AUDDAT