Cirrus Logic CS4205 - Manual (Page 38)

CS4205
38 DS489PP4
5.17 Audio Sample Rate Control Registers (Index 2Ch - 34h)
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.
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
Register
Index
SRC
SRC Enable Bit
(Index 2Ah)
2Ch PCM Front DAC Rate VRA
32h PCM L/R ADC Rate VRA
34h Mic ADC Rate VRM
Table 11. Audio Sample Rate Control Register Index
Sample Rate
(Hz)
SR[15:0], register
content (hex value)
SR[15:0], decode
range (hex value)
SR[15:11], decode
range (bin value)
8,000 1F40 0000 - 1FFF 00000 - 00011
9,600 2580 2000 - 27FF 00100 - 00100
11,025 2B11 2800 - 2FFF 00101 - 00101
13,714 3592 3000 - 37FF 00110 - 00110
16,000 3E80 3800 - 47FF 00111 - 01000
22,050 5622 4800 - 57FF 01001 - 01010
24,000 5DC0 5800 - 6FFF 01011 - 01101
32,000 7D00 7000 - 8FFF 01110 - 10001
44,100 AC44 9000 - AFFF 10010 - 10101
48,000 BB80 B000 - FFFF 10110 - 11111
Table 12. Directly Supported SRC Sample Rates for the CS4205