CS4205_05 Datasheet, PDF (38/81 Pages) Cirrus Logic – CrystalClear® Audio Codec ’97 for Portable Computing

CS4205
5.17 Audio Sample Rate Control Registers (Index 2Ch - 34h)
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
SR15 SR14 SR13 SR12 SR11 SR10 SR9 SR8 SR7 SR6 SR5 SR4 SR3 SR2 SR1 SR0
SR[15:0]
Sample Rate Select. The Audio Sample Rate Control Registers (Index 2Ch - 34h) control
playback and capture sample rates. The PCM Front DAC Rate Register (Index 2Ch) controls
the Front Left and Front Right DAC sample rates. The PCM L/R ADC Rate Register
(Index 32h) controls the Left and Right ADC sample rates. The Mic ADC Rate Register (Index
34h) controls the Microphone ADC sample rate. There are ten sample rates directly support-
ed by this register, shown in Table 12. Any value written to this register not contained in
Table 12 is not directly supported and will be decoded according to the ranges indicated in
the table. The range boundaries have been chosen so that only bits SR[15:11] of each regis-
ter will have to be considered. All register read transactions will reflect the actual value stored
(column 2 in Table 12) and not the one attempted to be written.
Default
BB80h. This value corresponds to 48 kHz sample rate.
Writes to the PCM Front DAC Rate Register (Index 2Ch) and the PCM L/R ADC Rate Register (Index 32h) are only
available in Variable Rate PCM Audio mode when the VRA bit in the Extended Audio Status/Control Register
(Index 2Ah) is ‘set’. If VRA = 0, writes to the register are ignored and the register will always read BB80h. Writes to
the Mic ADC Rate Register (Index 34h) are only available in Variable Rate Mic Audio mode when the VRM bit in the
Extended Audio Status/Control Register (Index 2Ah) is ‘set’. If VRM = 0, writes to the register are ignored and the
register will always read BB80h. Table 11 lists the SRC registers and their corresponding SRC enable bit.
Register
Index
2Ch
32h
34h
SRC
SRC Enable Bit
(Index 2Ah)
PCM Front DAC Rate
VRA
PCM L/R ADC Rate
VRA
Mic ADC Rate
VRM
Table 11. Audio Sample Rate Control Register Index
Sample Rate
(Hz)
8,000
9,600
11,025
13,714
16,000
22,050
24,000
32,000
44,100
48,000
SR[15:0], register
content (hex value)
1F40
2580
2B11
3592
3E80
5622
5DC0
7D00
AC44
BB80
SR[15:0], decode
range (hex value)
0000 - 1FFF
2000 - 27FF
2800 - 2FFF
3000 - 37FF
3800 - 47FF
4800 - 57FF
5800 - 6FFF
7000 - 8FFF
9000 - AFFF
B000 - FFFF
SR[15:11], decode
range (bin value)
00000 - 00011
00100 - 00100
00101 - 00101
00110 - 00110
00111 - 01000
01001 - 01010
01011 - 01101
01110 - 10001
10010 - 10101
10110 - 11111
Table 12. Directly Supported SRC Sample Rates for the CS4205
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