VS1005g Datasheet
10 VS1005 PERIPHERALS AND REGISTERS
10.16.1 Configuring Analog Modules for Mic and Line Input Modes
Analog modules must be configured to line or mic input modes before digital filters are used.
Example values of analog configuration registers for stereo line input and mic modes are given
in next table.
Analog Control Register Examples
Address
Register Line input mode Mic input mode
0xFECB ANA_CF1 0x0000
0xFECC ANA_CF0 0x0600
0xFED2 ANA_CF2 0x000B
0xFED3 ANA_CF3 0x0000
0x0000
0x0024
0x00CB
0x0009
10.16.2 Digital Filter Operation Modes
The FM_CF register has four bits that have effect on AD functionality. FM_CF_INIT register
is the digital filters’ power down. When the register is set the digital filters are operable. This
register can also be used to synchronize the stereo and mono AD filters when three channels
are used with same sample rate (no phase error).
The input to digital filters can also be selected from external ADCs. With FM_CF_UAD1,
FM_CF_UAD2 and FM_CF_UAD3 registers the filter’s input can be taken from external source.
In this mode the AD input sample rate must be XTAL clock/2 or XTAL clock/4 and the input must
be synchronized to vs1005 xtal oscillator clock. Vs1005 can provide both the xtal, xtal/2, and
xtal/4 clocks to external circuits.
FM_CF Bits
Name
Bits Description
FM_CF_UAD2
FM_CF_UAD1
FM_CF_UAD3
FM_CF_INIT
14 External input enable for stereo AD, right channel
13 External input enable for stereo AD, left channel
12 External input enable for mono AD
6
Software reset for AD and FM demodulator
The AD configuration register has bits to enable filters and to select sample rates. When the
filter is enabled also the interrupt request is generated and forwarded to the interrupt controller.
The decimation filter is included to decimate the demodulated FM signals downto 32kHz sample
rate but its input can be selected from other sources also. The filter’s input bit width is 18-bits.
AD_CF Bits
Name
Bits Description
AD_CF_AD23_FLP
AD_CF_DEC6SEL[1:0]
AD_CF_AD3FS[1:0]
AD_CF_ADFS[1:0]
9
Flip AD2 and AD3 inputs
8:7 Input selection for FM filter (decimation-by-6)
6:5 Sample rate selection for AD filter 3 (mono AD)
4:3 Sample rate selection for AD filters 1 and 2 (stereo
AD)
AD_CF_DEC6ENA
AD_CF_AD3ENA
AD_CF_ADENA
2
1
0
FM decimation filter enable
AD filter 3 enable (mono AD, line input 3)
AD filter 1 and 2 enable (stereo AD, line input 1
and 2)
Version: 0.2, 2012-03-16
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