pnx1700 NXP Semiconductors, pnx1700 Datasheet - Page 722

• Manufacturer Part Number: pnx1700
• Description: Connected Media Processor
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Volume 1 of 1
PNX17XX_SER_1
Preliminary data sheet
Figure 8:
0xFEEDB0EC
RxDescriptor
Receive example memory and registers
0xFEEDB0F0
0xFEEDB0EC
0xFEEDB204
0xFEEDB0F4
0xFEEDB0F8
0xFEEDB200
0xFEEDB1FC
0xFEEDB208
5.5.8 Device Driver Processes Receive Data
5.5.9 Receive example
1
1
1
1
Descriptor Array FIFO
0xFEEDB4111
0xFEEDB409
0xFEEDB419
0xFEEDB325
Control
Control
Control
Control
Packet
Packet
Packet
Packet
The device driver can be signaled to read the descriptors that have been handed over
to it by the hardware by observing status word flags (for example, RxDoneInt),
receiving interrupts, or polling for the case where RxProduceIndex –
RxConsumeIndex is not 0. The device driver should inspect the status words in the
status FIFO to check for multi-fragment packets and receive errors.
The device driver can forward receive data and status to higher-level software layers.
After data and status are processed, the descriptors, status words and data buffers
may be recycled and handed back to hardware by incrementing RxConsumeIndex.
Figure
bytes.
After reset, the values of the LAN100 DMA registers will be zero. During initialization,
the device driver must allocate the descriptor and status array in memory. In this
example, an array of four descriptors is allocated. The array is 4x2x4 bytes, and is
aligned on a 4-byte address boundary. Since the number of descriptors should match
the number of status words, the status array consists of four elements. The status
array is 4x2x4 bytes, and is aligned on an 8-byte address boundary. The device driver
writes the base address of the descriptor array (0xFEEDB0EC) to the RxDescriptor
register, and the base address of the status array (0xFEEDB1F8) to the RxStatus
7
7
7
7
Figure 8
illustrates the receive process in an example receiving a packet of 16
Rev. 1 — 17 March 2006
Fragment 0 buffer (8 bytes)
Fragment 1 buffer (8 bytes)
Fragment 3 buffer (8 bytes)
Fragment 2 buffer (8 bytes)
Fragments
Chapter 23: LAN100 — Ethernet Media Access Controller
0xFEEDB1F8
RxDescriptorNumber 3
RxStatus
RxConsumeIndex
RxProduceIndex
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Status Array FIFO
StatusTimestamp
StatusTimestamp
StatusTimestamp
StatusTimestamp
PNX17xx Series
StatusInfo
StatusInfo
StatusInfo
StatusInfo
7
7
3
0xFEEDB1F8
0xFEEDB210
0xFEEDB200
0xFEEDB208
23-49