cp3cn23 National Semiconductor Corporation, cp3cn23 Datasheet - Page 7

• Manufacturer Part Number: cp3cn23
• Description: Cp3cn23 Reprogrammable Connectivity Processor With Dual Can Interfaces
• Manufacturer: National Semiconductor Corporation

3.20
The Direct Memory Access Controller (DMAC) can speed
up data transfer between memory and I/O devices or be-
tween two memories, relative to data transfers performed di-
rectly by the CPU. A method called cycle-stealing allows the
CPU and the DMAC to share the CPU bus efficiently. The
DMAC implements four independent DMA channels. DMA
requests from a primary and a secondary source are recog-
nized for each DMA channel, as well as a software DMA re-
quest issued directly by the CPU. Table 1 shows the DMA
channel assignment on the CP3CN23 architecture. The fol-
lowing on-chip modules can assert a DMA request to the
DMAC:
Table 1 shows how the four DMA channels are assigned
to the modules listed above.
The interface can handle data words of either 8- or 16-bit
length and data frames can consist of up to four slots.
In the normal mode of operation, the interface only transfers
one word at a periodic rate. In the network mode, the inter-
face transfers multiple words at a periodic rate. The periodic
rate is also called a data frame and each word within one
frame is called a slot. The beginning of each new data frame
is marked by the frame sync signal.
•
•
•
•
Channel
CR16C (Software DMA request)
USART
Advanced Audio Interface
CVSD/PCM Converter
0
1
2
3
DMA CONTROLLER
Table 1 DMA Channel Assignment
Secondary
Secondary
Secondary
Secondary
Secondary
Primary/
Primary
Primary
Primary
Primary
CVSD/PCM
CVSD/PCM
Peripheral
Reserved
Unused
UART0
UART0
AAI
AAI
Transaction
Read/Write
Read
Read
Read
Write
Write
Write
N/A
7
3.21
The Serial Debug Interface module (SDI module) provides
a JTAG-based serial link to an external debugger, for exam-
ple running on a PC. In addition, the SDI module integrates
an on-chip debug module, which allows the user to set up to
eight hardware breakpoints on instruction execution and
data transfer. The SDI module can act as a CPU bus master
to access all memory mapped resources, such as RAM and
peripherals. Therefore it also allows for fast program code
download into the on-chip Flash program memory using the
JTAG interface.
3.22
In addition to providing the features needed for the next gen-
eration of embedded products, the CP3CN23 devices are
backed up by the software resources designers need for
rapid product development, including an operating system,
peripheral drivers, reference designs, and an integrated de-
velopment environment.
National Semiconductor offers a complete and industry-
proven application development environment for CP3CN23
applications, including the IAR Embedded Workbench,
iSYSTEM winIDEA and iC3000 Active Emulator, and Appli-
cation Software. See your National Semiconductor sales
representative for current information on availability and fea-
tures of emulation equipment and evaluation boards.
SERIAL DEBUG INTERFACE
DEVELOPMENT SUPPORT
www.national.com