Analog Devices CN-0506, Быстрый старт

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Circuit Note CN-0506
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SOFTWARE OVERVIEW
The FPGA reference designs provided for use with the CN0506
configure each ADIN1300 independently. Each PHY (ADIN1300)
is connected to a designated MAC interface, and there are three
supported interface modes between the ADIN1300 and the FPGA:
RGMII, MII, and RMII.
For each mode, there is a separate hardware design language
(HDL) because some modes require converters (for example, Giga-
bit MII (GMII) to RGMII). The operating mode must be selected in
the HDL to match the mode users wish to use in Linux.
The EVAL-CN0506-FMCZ connects to a standard low pin count
(LPC) FMC connector, which makes the software design portable to
many different FPGA development boards.
The Linux device tree supported for the different modes and carrier
combinations can be found on the CN0506 HDL page . For more
information on the standard Analog Devices, Inc., Linux image, see
the FPGA Image user guide .
BOARD LAYOUT CONSIDERATIONS
Ethernet signal layout is critical, especially at gigabit speeds. Sig-
nals are routed to RJ45 jacks as 100 Ω, controlled impedance pairs.
Data and clock signals to the carrier, while operating at lower clock
rates, have edge rates that necessitate careful layout. Signals on
the EVAL-CN0506-FMCZ are kept as short as possible, while signal
trace length and impedance matching on the carrier board must be
carefully considered when connecting the CN0506. These factors
are important to the overall speed and performance of the CN0506,
but must be considered separately.
Figure 4 shows the 1000BASE-T maximum drop point from V2 to
V1 at 98.7%.
Figure 4. Peak PHY Differential Output Voltage
PERFORMANCE RESULTS
Several tests were conducted using the CN0506, including a mode
verification test, a speed test, and a cable length drive test.
The EVAL-CN0506-FMCZ was tested at different modes with in-
creasing cable lengths and with no packet loss. The results are
detailed in Table 2 and Table 3 for a 4 meter cable and for a 154
meter cable, respectively.
Table 2 and Table 3 show the frame checker count registers
(FC_FRM_CNT_H and FC_FRM_CNT_L) and the receive error
count register (RX_ERR_CNT) readback values of the ADIN1300
at the local and remote Ethernet PHY locations for a short cable
transmission and a long cable transmission, respectively.
Table 2. EVAL-CN0506-FMCZ Evaluation System with 4 Meter Cable
Speed
(Mbps) Mode FC_FRM_CNT_H
Local Ethernet PHY
FC_FRM_CNT_L RX_ERR_CNT FC_FRM_CNT_H
Remote Ethernet PHY
FC_FRM_CNT_L RX_ERR_CNT Status
1000 RGMII 744 6314 0 744 6314 0 Pass
100 RGMII 74 26853 0 74 26853 0 Pass
10 RGMII 7 2890 0 7 2890 0 Pass
100 MII 74 26849 0 74 26849 0 Pass
10 MII 7 28900 0 7 28900 0 Pass
Table 3. EVAL-CN0506-FMCZ Evaluation System with 154 Meter Cable
Speed
(Mbps) Mode FC_FRM_CNT_H
Local Ethernet PHY
FC_FRM_CNT_L RX_ERR_CNT FC_FRM_CNT_H
Remote Ethernet PHY
FC_FRM_CNT_L RX_ERR_CNT Status
1000 RGMII 744 7693 0 744 7693 0 Pass
100 RGMII 74 26847 0 74 26847 0 Pass
10 RGMII 7 28900 0 7 28900 0 Pass
100 MII 74 26849 0 74 26849 0 Pass
10 MII 7 268900 0 7 268900 0 Pass