cp3cn23 National Semiconductor Corporation, cp3cn23 Datasheet - Page 131
![no-image](/images/no-image-200.jpg)
cp3cn23
Manufacturer Part Number
cp3cn23
Description
Cp3cn23 Reprogrammable Connectivity Processor With Dual Can Interfaces
Manufacturer
National Semiconductor Corporation
Datasheet
1.CP3CN23.pdf
(246 pages)
- Current page: 131 of 246
- Download datasheet (3Mb)
19.0 CVSD/PCM Conversion Module
The CVSD/PCM module performs conversion between
CVSD data and PCM data, in which the CVSD encoding is
as defined in the Bluetooth specification and the PCM en-
coding may be 8-bit µ-Law, 8-bit A-Law, or 13-bit to 16-bit
Linear.
The CVSD conversion module operates at a fixed rate of
125 µs (8 kHz) per PCM sample. On the CVSD side, there
19.1
The Aux2 clock (generated by the Clock module described
in Section 11.9) must be configured, because it drives the
CVSD module. Software must set its prescaler to provide a
2 MHz input clock based upon the System Clock (usually
12 MHz). This is done by writing an appropriate divisor to
the ACDIV2 field of the PRSAC register. Software must also
enable the Aux2 clock by setting the ACE2 bit within the
CRCTRL register. For example:
PRSAC &= 0x0f;
// Set Aux2 prescaler to generate
// 2 MHz (Fsys = 12 MHz)
PRSAC |= 0x50;
CRCTRL |= ACE2; // Enable Aux2 clk
The module converts between PCM data and CVSD data at
a fixed rate of 8 kHz per PCM sample. Due to compression,
the data rate on the CVSD side is only 4 kHz per CVSD
sample.
If PCM interrupts are enabled (PCMINT is set) every 125 µs
(8 kHz) an interrupt will occur and the interrupt handler can
operate on some or all of the four audio streams CVSD in,
CVSD out, PCM in, and PCM out. Alternatively, a DMA re-
quest is issued every 125 µs and the DMA controller is used
to move the PCM data between the CVSD/PCM module
and the audio interface.
If CVSD interrupts are enabled, an interrupt is issued when
either one of the CVSD FIFOs is almost empty or almost full.
On the PCM data side there is double buffering, and on the
CVSD side there is an eight word (8 × 16-bit) FIFO for the
read and write paths.
OPERATION
16-Bit 8 kHz
u/A-Law
Figure 57. CVSD/PCM Converter Block Diagram
16-Bit 8 kHz
u/A-Law
Clock Input
2 MHz
Engine
Filter
Peripheral Bus
131
Interrupt
16-Bit
64 kHz
16-Bit
64 kHz
is a read and a write FIFO allowing up to 8 words of data to
be read or written at the same time. On the PCM side, there
is a double-buffered register requiring data to be read and
written every 125 µs. The intended use is to move CVSD
data into the module with a CVSD interrupt handler, and to
move PCM data with DMA. Figure 57 shows a block dia-
gram of the CVSD to PCM module.
Inside the module, a filter engine receives the 8 kHz stream
of 16-bit samples and interpolates to generate a 64 kHz
stream of 16-bit samples. This goes into a CVSD encoder
which converts the data into a single-bit delta stream using
the CVSD parameters as defined by the Bluetooth specifi-
cation. There is a similar path that reverses this process
converting the CVSD 64 kHz bit stream into a 64 kHz 16-bit
data stream. The filter engine then decimates this stream
into an 8 kHz, 16-bit data stream.
19.2
During conversion between CVSD and PCM, any PCM for-
mat changes are done automatically depending on whether
the PCM data is µ-Law, A-Law, or Linear. In addition to this,
a separate function can be used to convert between the var-
ious PCM formats as required. Conversion is performed by
setting up the control bit CVCTL1.PCMCONV to define the
conversion and then writing to the LOGIN and LINEARIN
registers and reading from the LOGOUT and LINEAROUT
registers. There is no delay in the conversion operation and
it does not have to operate at a fixed rate. It will only convert
between µ-Law/A-Law and linear, not directly between µ-
Law and A-Law. (This could easily be achieved by convert-
ing between µ-Law and linear and between linear and A-
Law.)
If a conversion is performed between linear and µ-Law log
PCM data, the linear PCM data are treated in the left-
aligned 14-bit linear data format with the two LSBs unused.
If a conversion is performed between linear and A-Law log
PCM data, the linear PCM data are treated in the left-
aligned 13-bit linear data format with the three LSBs un-
used.
Encoder
Decoder
CVSD
CVSD
DMA
PCM CONVERSIONS
16-Bit Shift Reg
16-Bit Shift Reg
1-Bit 64 kHz
1-Bit 64 kHz
DS058
www.national.com
Related parts for cp3cn23
Image
Part Number
Description
Manufacturer
Datasheet
Request
R
![mma1270keg](/images/no-image3.png)
Part Number:
Description:
Freescale Semiconductor Technical Data
Manufacturer:
National Semiconductor Corporation
Datasheet:
![ADC12034](/images/no-image3.png)
Part Number:
Description:
Self-calibrating 12-bit Plus Sign Serial I/o A/d Converters With Mux And Sample/hold
Manufacturer:
National Semiconductor Corporation
Datasheet:
![LMX2350](/images/no-image3.png)
Part Number:
Description:
Pllatinum Tm Fractional N Rf / Integer N If Dual Low Power Frequency Synthesizer
Manufacturer:
National Semiconductor Corporation
Datasheet:
![LMX2324](/images/no-image3.png)
Part Number:
Description:
Pllatinum? 2.0 Ghz Frequency Synthesizer For Rf Personal Communications
Manufacturer:
National Semiconductor Corporation
Datasheet:
![LMX2301](/images/no-image3.png)
Part Number:
Description:
Pllatinumtm 160 Mhz Frequency Synthesizer For Rf Personal Communications
Manufacturer:
National Semiconductor Corporation
Datasheet:
![NDS8963](/images/no-image3.png)
Part Number:
Description:
Dual N-channel Enhancement Mode Field Effect Transistor
Manufacturer:
National Semiconductor Corporation
Datasheet:
![LM1201](/images/no-image3.png)
Part Number:
Description:
Video Amplifier System (obsolete)
Manufacturer:
National Semiconductor Corporation
Datasheet:
![LM3501TL-16](/images/no-image3.png)
Part Number:
Description:
Synchronous Step-up DC/DC Converter For White Led Applications
Manufacturer:
National Semiconductor Corporation
Datasheet:
![AD9621](/images/no-image3.png)
Part Number:
Description:
CLC420 - High Speed, Voltage Feedback op Amp, Package: Lcc, Pin Nb=20
Manufacturer:
National Semiconductor Corporation
Datasheet:
![LM2403](/images/no-image3.png)
Part Number:
Description:
Monolithic Triple 4.5 CRT Driver
Manufacturer:
National Semiconductor Corporation
Datasheet:
![LM592M](/images/no-image3.png)
Part Number:
Description:
Differential Video Amplifier
Manufacturer:
National Semiconductor Corporation
Datasheet:
![ADC10061](/images/no-image3.png)
Part Number:
Description:
ADC10061 - 10-Bit 600 NS A/D Converter With Input Multiplexer And Sample/Hold, Package: Soic Wide, Pin Nb=20
Manufacturer:
National Semiconductor Corporation
Datasheet:
![DS36277TMX](/images/no-image3.png)
Part Number:
Description:
DS36277 - Dominant Mode Multipoint Transceiver, Package: Soic Narrow, Pin Nb=8
Manufacturer:
National Semiconductor Corporation
Datasheet:
![DS3654](/images/no-image3.png)
Part Number:
Description:
Printer Solenoid Driver
Manufacturer:
National Semiconductor Corporation
Datasheet:
![DS3662](/images/no-image3.png)
Part Number:
Description:
Quad High Speed Trapezoidal Bus Transceiver
Manufacturer:
National Semiconductor Corporation
Datasheet: