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92 www.xilinx.com Ethernet AVB Endpoint User Guide
UG492 July 23, 2010
Chapter 10: Configuration and Status
Ethernet AVB Endpoint Address Space
Rx PTP Packet Buffer Address Space
The Address space of the “Rx PTP Packet Buffer” is 4k bytes, from PLB_base_address to
(PLB_base_address + 0x0FFF). This represents the size of a single Virtex®-5 FPGA block
RAM pair (4k bytes). Every byte of this Block RAM can be read from the PLB. See “Rx PTP
Packet Buffer” for operation.
Tx PTP Packet Buffer Address Space
The Address space of the “Tx PTP Packet Buffer” is continuous from (PLB_base_address +
0x1000) to (PLB_base_address + 0x17FF), representing the size of a single Virtex-5 FPGA
Block 18k RAM (2k bytes). Every byte of this Block RAM is read/write accessible via the
PLB. See “Tx PTP Packet Buffer” for operation.
Ethernet Audio Video End Point Configuration Registers
Tx PTP Packet Control Register
Table 10-1 defines the associated control register of the “Tx PTP Packet Buffer,” used by the
“Software Drivers” to request the transmission of the PTP frames.
Table 10-1: Tx PTP Packet Buffer Control Register (PLB_base_address + 0x2000)
Bit no Default Access Description
7-0 0 WO tx_send_frame bits. The Tx PTP Packet Buffer is split into
8 regions of 256 bytes. Each of these can contain a separate
PTP frame. There is 1 tx_send_frame bit for each of the 8
regions.
Each bit, when written to ‘1’, will cause a request to be
made to the “Tx Arbiter.” When access is granted, the
frame contained within the respected region will be
transmitted.
If read, will always return 0.
15-8 0 RO tx_frame_waiting indication. The Tx PTP Packet Buffer is
split into 8 regions of 256 bytes, each of which can contain
a separate PTP frame. There is 1 tx_frame_waiting bit for
each of the 8 regions.
Each bit, when logic 1, indicates that a request has been
made for frame transmission to the “Tx Arbiter,” but that
a grant has not yet occurred. When the frame has been
successfully transmitted, the bit will be set to logic 0.
This bit allows the microprocessor to run off a polling
implementation as opposed to the Interrupts.
18-16 0 RO tx_packet. indicates the number (block RAM bin position)
of the most recently transmitted PTP packet.
31-19 0 RO Unused
Note: A read or a write to this register clears the interrupt_ptp_tx interrupt (asserted after each
successful PTP packet transmission).