VSC8502 Reference Board
VPPD-03822 VSC8502 User Guide Revision 1.0
3
3
General Description
The evaluation board, shown in Figure 1, provides the user a way to evaluate the VSC8502 device in
multiple configurations. Two RJ-45 connectors are provided for copper media interfaces. The MAC
interface (RGMII) is exposed via 0.1 inch steakheaders, J31 - J53. For standalone access to all of the
features of the device, an external microcontroller is used to configure the VSC8502 via the MDIO bus.
The GUI enables the user to read and write device registers.
3.1
Copper Port RJ45 Connections
PHY ports 0 and 1 use generic RJ45 connectors with discrete Halo TG1G-S032NYRL magnetics.
3.2
RGMII MAC Connectors
The parallel MAC interface is available through 0.1 inch headers. The layout is such that by installing
jumpers the RX and TX signals can be looped on board. When mating to a MAC board, a specialized
cable will need to be constructed.
The following is the RGMII connectors positioned in the board:
Table 1 • RGMII Connector Positions
Channel 1
Channel 0
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
RXD2
RXDV_CTL
RXD0
RXD3
RXD1
RXCLK
RXD3
RXDV_CTL
RXD2
RXD0
RXD1
RXCLK
TXD2
TXDV_CTL
TXD0
TXD3
TXD1
TXCLK
TXD3
TXDV_CTL
TXD2
TXD0
TXD1
TXCLK
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
3.3
Static Controls (SW1)
Three static control signals are set by the DIP switch SW1.
Signal Name
Description
Position for Normal Operation
REFCLK_SEL
Select the input frequency to the device.
0: 125 MHz
1: 25 MHz
1
NRESET
Hold the device in rest.
0: Reset state
1: Normal device operation
1
COMA_MODE
Hold the device in coma state.
0: Disabled
1: Enabled
0
3.4
Clocking
VSC8502RD board is equipped with a 2.5V CMOS, 25.00 MHz standard clock oscillator (U5), while the
VSC8502RD-VR board uses a 3.3 V CMOS version.
3.5
Software Interface Microcontroller Card
A Silabs F340 microcontroller is included to facilitate a software interface to the registers on the
VSC8502 through a USB port.
Note: Alternatively, a Rabbit card is available for an IP-based manager of the PHY register space,
installed in the keep-out area (U6) of the board’s top-side. Or, MDC and MDIO can be accessed on stake
header J10 if desired for another microcontroller to host the PHY register space.
