We would like to connect the RGMII port on SwitchBlox Rugged to another device via a cable. Can you provide some information on the electrical specifications of the RGMII port?
We haven’t officially tested whether this is possible, and RGMII isn’t really designed to be transmitted on cables very far. RGMII is very sensitive to skew between the clock and data signals, so if you are using a cable, it’s important to keep the cable short, and that the individual conductors in the cable are reasonably length matched.
Another issue is that the RGMII connector on SwitchBlox Rugged is not really designed to mate with a cable. It’s designed for board-to-board connections; specifically for mating two SwitchBlox Rugged boards together to form a 10 port switch. The part we use for the RGMII connector (0873401824) has a short pin depth and there is no retaining method on the board.
A cable like this (TCMD-08-T-02.00-01-N) might work, it has male pins that can plug into the header on the board, but you’ll still need to figure out a way to keep the cable in place.
RGMII Pinout
Below is the pinout of the header.
NC = Not connected
RX pins are outputs from the board
TX pins are input to the board.
Electrical Specifications
Voltage level: 3.3V
Clock frequency: 125MHz
Ingress delay added to incoming TX clock = 0ns
Exgress delay added to outgoing RX clock = 1.5ns
Clock specifications
(Taken from the KSZ8567S datasheet)