Jumpers, Buttons, and LEDs

PLL Jumper

Leave this jumper open if you want the EM1000 on the NB1000 to run at full speed (88.4736MHz). Close the jumper if you want the EM1000 to run at 1/8th speed (11.0592MHz). Note that the jumper state is only recognized after power-up or an external reset (caused by pressing the reset button). The PLL mode can also be changed programmatically. For more information see the Power, Reset, PLL Control, and Mode Selection Lines topic of the EM1000 documentation.

MD Jumper and Mode Button

The function of the mode button is described in Setup (MD) Button (Line). On the NB1000, the MD jumper is connected in parallel with the button.

US Jumper

This jumper selects the serial port of the EM1000 that will be used for firmware upgrades. When the jumper is opened, serial port 1 is used — the TX0 (#17) and RX0 (#19) lines on the IC1000 interboard cable. Interface boards typically implement serial port 1, thus making serial firmware upgrades possible.

When the US jumper is closed, the debug serial port is used.

Reset Button

This button is connected to the RST pin of the EM1000. Pressing this button causes an "external" reset.

Ethernet Status LEDs

These are yellow and green LEDs connected to the EY and EG pins of the EM1000. Further information on status LEDs can be found in Status LEDs.