app385| Application Note
Application Note 385 DS3131 Step by Step Configuration--Bridge Mode
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OVERVIEW
This application note describes an example of how to configure a single port on the DS3131 operating in bridge mode. Additionally, this example describes how to construct, send, receive, and check a packet in loopback mode on that port. This application note is presented as a coding example for easy adaptation to end-user applications. The local bus can operate in two modes in DS3131: PCI bridge mode and configuration bus mode. The PCI bridge mode allows the host on the PCI bus to access the local bus. The PCI bus is used to control and monitor the DS3131 and transfer the packet data. The DS3131 maps data from the PCI bus to the local bus. (Refer to the DS3131 data sheet, Section 10.) This example has the following configuration: Only port 1 and channel 1 of the DS3131 are assigned. All other ports are not used. HDLC channel 1 of the DS3131 is assigned four Rx FIFO blocks, four Tx FIFO blocks, an Rx FIFO high watermark of 3, and a Tx low watermark of 1. A 16-byte packet is constructed in host memory us
ing one Tx buffer, one Tx descriptor, and one Tx pending queue entry. Since the DS3131 is in loopback mode, when the packet is transmitted it is also be received by the DS3131. The received packet is written to host memory using one Rx buffer, one Rx descriptor, and one Rx done queue entry. The host memory is configured as follows: Receive Side: Rx free queue base address (RFQBA1/0) = 0x10000000 Rx done queue base address (RDQBA1/0) = 0x10000100 Rx descriptor base address (RDBA1/0) = 0x10000200 Rx buffer base address = 0x10001000 Transmit Side: Tx pending queue base address (TPQBA1/0) Tx done queue base address (TDQBA1/0) Tx descriptor base address (TDBA1/0) Tx buffer base address
= = = =
0x10000300 0x10000400 0x10000500 0x10002000
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