Aic33 Interface - Spectrum Digital TMS320DM6437 Technical Reference

Spectrum Digital, Inc

2.4 AIC33 Interface

The EVM uses a Texas Instruments TLV320AIC33 stereo codec for input and output of
audio signals. The codec samples analog signals on the microphone or line inputs and
converts them into digital data so it can be processed by the DSP. When the DSP is
finished with the data it uses the codec to convert the samples back into analog signals
on the line output so the user can hear the output.
The codec communicates using two serial channels, one to control the codec's internal
configuration registers and one to send and receive digital audio samples. The I
is used as the unidirectional control channel. The control channel is generally only used
when configuring the codec, it is typically idle when audio data is being transmitted,
The default configuration is to use the McBSP is used as the bi-directional data
channel. However, optionally the McASP can be used to drive the data channel. Data
channel selection is controller via an on board I
through the data channel. Many data formats are supported based on the three
variables of sample width, clock signal source and serial data format. The EVM
examples generally use a 16-bit sample width with the codec in master mode so it
generates the frame sync and bit clocks at the correct sample rate without effort on the
DSP side.
The codec has a programmable clock from a PLL1705 PLL device. The default system
clock is 18.432 Mhz. The internal sample rate generate subdivides the 18.432 MHz
clock to generate common frequencies such as 48KHz and 8KHz. The sample rate is
set by a codec register. The figure below shows the codec interface on the DM6437
EVM.
McASP or McBSP
AXR[0]
AXR[1]
ACLKR
ACLKX
AFSR
AFSX
2-4
2
I C
Control
SCL SCL
SDA SDA
2
I C Format
Digital
DX
DOUT
DR
DIN
CLKR
I2S Format
BCLK
CLKX
WCLK
FSR
FSX
Figure 2-2, DM6437 EVM CODEC INTERFACE
2
C expander. All audio data flows
AIC33 Codec
Control Registers
Analog
MIC IN
ADC
LINE IN
DAC LINE OUT
HP OUT
DM6437 EVM Technical Reference
2
C bus
MIC IN
LINE IN
LINE OUT
HP OUT