AT83C51SND1C_03 ATMEL [ATMEL Corporation], AT83C51SND1C_03 Datasheet - Page 75

• Manufacturer Part Number: AT83C51SND1C_03
• Description: Single-Chip Flash Microcontroller with MP3 Decoder and Human Interface
• Manufacturer: ATMEL [ATMEL Corporation]

Figure 51. Audio Output Format
Audio Buffer
4109E–8051–06/03
DOUT
DOUT
DOUT
DOUT
DOUT
DCLK
DCLK
DCLK
DCLK
DCLK
DSEL
DSEL
DSEL
DSEL
DSEL
MSB
LSB
1
1
1
1
1
MSB
MSB
B14
2
2
2
B14
B14
MSB B16
The data converter receives its audio stream from 2 sources selected by the SRC bit in
AUDCON1 register. When cleared, the audio stream comes from the MP3 decoder (see
Section “MP3 Decoder”, page 62) for song playing. When set, the audio stream is com-
ing from the C51 core for voice or sound playing.
As soon as first audio data is input to the data converter, it enables the clock generator
for generating the bit and word clocks.
In voice or sound playing mode, the audio stream comes from the C51 core through an
audio buffer. The data is in 8-bit format and is sampled at 8 kHz. The audio buffer
adapts the sample format and rate. The sample format is extended to 16 bits by filling
the LSB to 00h. Rate is adapted to the DAC rate by duplicating the data using DUP1:0
bits in AUDCON1 register according to Table 83.
The audio buffer interfaces to the C51 core through three flags: the sample request flag
(SREQ in AUDSTA register), the under-run flag (UNDR in AUDSTA register) and the
busy flag (AUBUSY in AUDSTA register). SREQ and UNDR can generate an interrupt
request as explained in Section "Interrupt Request", page 76. The buffer size is 8 Bytes
large. SREQ is set when the samples number switches from 4 to 3 and reset when the
samples number switches from 4 to 5; UNDR is set when the buffer becomes empty sig-
naling that the audio interface ran out of samples; and AUBUSY is set when the buffer is
full.
3
3
3
Left Channel
Left Channel
Left Channel
Left Channel
Left Channel
16
15
16-bit LSB Justified Format with DSIZ = 1 and JUST4:0 = 10000.
18-bit LSB Justified Format with DSIZ = 1 and JUST4:0 = 01110.
MSB/LSB Justified Format with DSIZ = 0 and JUST4:0 = 00000.
MSB B14
17
16
LSB
I
I
2
2
S Format with DSIZ = 0 and JUST4:0 = 00001.
S Format with DSIZ = 1 and JUST4:0 = 00001.
13
17
13
18
B2
14
18
14
30
B1
B1
B1
15
15
31
31
LSB
LSB
LSB
B1
16
32
16
32
32
MSB
LSB
1
1
1
1
1
MSB
MSB
B15
2
2
2
B14
B14
MSB B16
3
3
3
16
15
Right Channel
Right Channel
Right Channel
Right Channel
Right Channel
MSB B14
17
16
LSB
13
17
13
18
AT8xC51SND1C
B2
14
18
14
30
B1
B1
B1
15
15
31
31
LSB
LSB
LSB
B1
16
32
16
32
32
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