ADSP-BF523C AD [Analog Devices], ADSP-BF523C Datasheet - Page 21

• Manufacturer Part Number: ADSP-BF523C
• Description: Blackfin Embedded Processor 289-ball MBGA package
• Manufacturer: AD [Analog Devices]

NOTE: ADC AND DAC CAN RUN AT DIFFERENT RATES
OTE: ADC AND DAC CAN RUN AT DIFFERENT RATES
Preliminary Technical Data
MASTER AND SLAVE MODE OPERATION
The CODEC can be configured as either a master or slave mode
device. As a master mode device the CODEC controls sequenc-
ing of the data and clocks on the digital audio interface. As a
slave device the CODEC responds with data to the clocks it
receives over the digital audio interface. The mode is set with
the MS bit of the control register as shown in
Table 15. Programming Master/Slave Modes
As a master mode device the CODEC controls the sequencing of
data transfer (ADCDAT, DACDAT) and output of clocks
(CODEC_BCLK, ADCLRC, DACLRC) over the digital audio
interface. It uses the timing generated from either its on-board
crystal or the CODEC_MCLK input as the reference for the
clock and data transitions. This is illustrated in
DAT is always an output from the CODEC and DACDAT is
always an input to the CODEC whether in master or slave
mode.
As a slave device the CODEC sequences the data transfer
(ADCDAT, DACDAT) over the digital audio interface in
response to the external applied clocks (CODEC_BCLK,
ADCLRC, DACLRC). This is illustrated in
The CODEC relies on controlled phase relationships between
audio interface CODEC_BCLK, DACLRC and the master
CODEC_MCLK or CODEC_CLKOUT. To avoid timing haz-
ards, see
information.
Register
Address
000 0111 6
CODEC
CODEC
CODEC Clock Timing on Page 34
CODEC_BCLK
CODEC_BCLK
Bit Label Default Description
ADCLRC
DACLRC
ADCDAT
DACDAT
ADCLRC
DACLRC
MS
ADCDAT
DACDAT
Figure 24. Master Mode
Figure 25. Slave Mode
0
Master Slave Mode Control
1 = Enable Master Mode
0 = Enable Slave Mode
TSCLKx/RSCLKx
TFSx
RFSx
DRxPRI/DRxSEC
DTxPRI/DTxSEC
TSCLKx/RSCLKx
TFSx
RFSx
DRxPRI/DRxSEC
DTxPRI/DTxSEC
Figure
for detailed
Table
Figure
25.
Rev. PrC | Page 21 of 44 | June 2008
15.
BLACKFIN
24. ADC-
BLACKFIN
ADSP-BF523C/ADSP-BF525C/ADSP-BF527C
AUDIO DATA SAMPLING RATES
The CODEC provides for two modes of operation (normal and
USB) to generate the required DAC and ADC sampling rates.
Use
Table 16. Sample Rate Control
In normal mode, the user controls the sample rate by using an
appropriate CODEC_MCLK or crystal frequency and the sam-
ple rate control register setting. The CODEC can support
sample rates from 8K samples/s up to 96K samples/s.
In USB mode, a fixed CODEC_MCLK or crystal frequency of 12
MHz is used to generate sample rates from 8K samples/s to
96K samples/s. It is called USB mode since the common USB
clock is 12 MHz. The CODEC can generate all the normal audio
sample rates from this one master clock, without the need for
different master clocks or PLL circuits.
The CODEC offers the user the ability to sample the ADC and
DAC at different rates under software control in both normal
and USB modes. This reduces the burden on a controlling pro-
cessor. However, signal processing in the ADC and DAC over-
sampling filters is tightly coupled to minimize power consump-
tion. For that reason, only the combinations of sample rates
listed in the following sections are supported. These rates are
expected to be the combinations used in typical audio systems.
Normal Mode Sample Rates
In normal mode, the CODEC_MCLK/crystal oscillator is set up
according to the desired sample rates of the ADC and DAC. For
ADC or DAC sampling rates of 8, 32, 48 or 96 kHz,
CODEC_MCLK frequencies of either 12.288 MHz (256 × f
18.432 MHz (384 × f
rates of 8, 44.1 or 88.2 kHz—CODEC_MCLK frequencies of
either 11.2896 MHz (256 × f
used.
Table 17
combinations. For example if the user wishes to use the CODEC
in normal mode with the ADC and DAC sample rates at 48 kHz
Register
Address
0001000 0 USB/
Table 16
can be used to set up the device for various sample rate
Bit Label
1 BOSR
5:2 SR[3:0]
NORMAL
to program normal and USB modes.
S
) can be used. For ADC or DAC sampling
Default Description
0
0
0000
S
) or 16.9344 MHz (384 × f
Mode Select
1 = USB mode (250/272 × f
0 = Normal mode (256/384 × f
Base Over-Sampling Rate
USB Mode
0 = 250 × f
1 = 272 × f
Normal Mode 96/88.2 kHz
0 = 256 × f
0 = 128 × f
1 = 384 × f
1 = 192 × f
ADC and DAC sample rate control
(see
and
Page
USB Mode Sample Rates on
Normal Mode Sample Rates
23)
S
S
S
S
S
S
S
) can be
S
)
S
) or
S
)