Техническая Спецификация для Atmel Evaluation Kit for AT32uC3A0512, 32-Bit AVR Microcontroller Atmel ATEVK1105 ATEVK1105
Модели
ATEVK1105
451
AT32UC3A
29.6
Programming Interface
29.6.1
Initialization
29.6.1.1
Configuration
Initialization of the MACB configuration (e.g. frequency ratios) must be done while the transmit
and receive circuits are disabled. See the description of the network control register and network
configuration register later in this document.
29.6.1.2
Receive Buffer List
Receive data is written to areas of data (i.e., buffers) in system memory. These buffers are listed
in another data structure that also resides in main memory. This data structure (receive buffer
queue) is a sequence of descriptor entries as defined in
. It points to this data structure.
Figure 29-2.
Receive Buffer List
To create the list of buffers:
1. Allocate a number (
1. Allocate a number (
n
) of buffers of 128 bytes in system memory.
2. Allocate an area 2
n
words for the receive buffer descriptor entry in system memory and
create
n
entries in this list. Mark all entries in this list as owned by MACB, i.e., bit 0 of
word 0 set to 0.
3. If less than 1024 buffers are defined, the last descriptor must be marked with the wrap bit
(bit 1 in word 0 set to 1).
4. Write address of receive buffer descriptor entry to MACB register receive_buffer queue
pointer.
5. The receive circuits can then be enabled by writing to the address recognition registers
and then to the network control register.
Receive Buffer Queue Pointer
(MAC Register)
Receive Buffer 0
Receive Buffer 1
Receive Buffer N
Receive Buffer Descriptor List
(In memory)
(In memory)
32058K
AVR32-01/12