wm9713 Wolfson Microelectronics plc, wm9713 Datasheet - Page 44

• Manufacturer Part Number: wm9713
• Description: Ac?97 Audio + Touchpanel Codec
• Manufacturer: Wolfson Microelectronics plc

WM9713L
VARIABLE RATE AUDIO / SAMPLE RATE CONVERSION
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By using an AC’97 Rev2.2 compliant audio interface, the WM9713L can record and playback at all
commonly used audio sample rates, and offer full split-rate support (i.e. the DAC, ADC and
AUXDAC sample rates are completely independent of each other – any combination is possible).
The default sample rate is 48kHz. If the VRA bit in register 2Ah is set, then other sample rates can
be selected by writing to registers 2Ch, 32h and 2Eh. The AC-Link continues to run at 48k frames per
second irrespective of the sample rate selected. However, if the sample rate is less than 48kHz, then
some frames do not carry an audio sample.
Table 21 Audio Sample Rate Control
Note:
Changing the ADC and / or DAC sample rate will only be effective if the ADC’s and DAC’s are
enabled and powered up before the sample rate is changed. This is done by setting the relevant bits
in registers 26h and 3Ch, as well as the VRA bit in register 2Ah.
The process is as follows:
1.
2.
3.
2Ah
Extended
Audio
Stat/Ctrl
2Ch
Audio DAC
Sample Rate
32h
Audio ADC
Sample Rate
2Eh
AUXDAC
Sample Rate
REGISTER
ADDRESS
Enable and power up ADC’s and or DAC’s in registers 26h and 3Ch.
Enable VRA bit in 2Ah, bit 0.
Change the sample rate in the respective register.
0
15:0
15:0
15:0
BIT
VRA
DACSR
ADCSR
AUXDA
CSR
LABEL
0 (OFF)
BB80h
(48kHz)
BB80h
(48kHz)
BB80h
(48kHz)
DEFAULT
Variable Rate Audio Control
1 = Enable VRA
0 = Disable VRA (ADC and DAC run at
48kHz)
Note: When VRA=1, sample rates are
controlled by 2Ch, 2Eh and 32h
Stereo DAC Sample Rate Control
1F40h = 8kHz
2B11h = 11.025kHz
2EE0h = 12kHz
3E80h = 16kHz
5622h = 22.05kHz
5DC0h = 24kHz
7D00h = 32kHz
AC44h = 44.1kHz
BB80h = 48kHz
Any other value defaults to the nearest
supported sample rate
Stereo ADC Sample Rate Control
Values as DACSR
AUXDAC Sample Rate Control
Values as DACSR
DESCRIPTION
PP Rev 3.2 September 2008
Pre-Production
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