GX3 FAQ - KBA218996

Version: **

 

Question:

Does GX3 support Power over Ethernet (PoE)?

 

Answer:

Yes. GX3 supports PoE and allows to implement a PoE part on the GX3 transformer circuit to support PoE applications. However, the recommended PoE reference circuit needs to be provided by the PoE part vendor. In addition, GX3 will not support commands such as Cisco Discovery Protocol (CDP) and Link Layer Discovery Protocol (LLDP) for PoE applications. 

Question: Does GX3 support MDI/MDI-X mode automatic transfer? 

Answer: Yes. GX3 supports MDI/MDI-X mode for automatic transfer of data. It supports parallel detection and automatic polarity correction. It also supports crossover detection and auto-correction.

‘Parallel detection and automatic polarity correction’ allows a device at one end of a link segment to advertise its abilities to the device at the other end (its link partner). This function detects information defining the abilities of the link partner and determines if the two devices are compatible. 

‘Crossover detection and auto-correction’ allows a device to detect if the connection requires a crossover, and automatically chooses the MDI or MDI-X configuration to properly match the other end of the link on the network interface.

Question: How do you test Ethernet signal quality tests?

Answer: The GX3 will respond to the test pattern or mode requests from the test equipment and send the test code patterns for 10M/100M/1000M. This can be done by binding GX3 to the Windows test driver; the Windows IEEE 802.3 test tool will show all the tests required for 10M/100M/1000M. 

Question: What is the purpose of connecting a 22-Ω resistor between CLKOUT and CLKIN?

Answer: The 22-Ω resistor connected between CLKOUT and CLKIN matches the impedance of the internal PLL clock generator. The external 25-MHz crystal or oscillator, via the XTALIN/XTALOUT pins, provides the reference clock to the internal oscillator circuit to generate a clock for the embedded Ethernet PHY, embedded USB PHY, and base clock for the ASIC. If an external oscillator is being used instead of a crystal, the external clock is connected to the XTALIN pin and the XTALOUT pin can be left open (NC).

Question: Does GX3 support the Communication Device Class (CDC) protocol?

Answer: GX3 is a vendor class device and its driver will automatically be loaded from the internet if the PC is connected to WiFi or internet other than that of GX3. So, GX3 will not support CDC protocols. 

Question: Can the GX3 driver be loaded in the EEPROM or can the EEPROM configuration settings be loaded from the GX3 driver?

Answer: No. Loading of the GX3 driver in the EEPROM and loading of the configuration settings from the GX3 driver is not possible. 

Question: Are the GPIO[0:3] pins pulled up or pulled down by default?

Answer: GPIO[0:3] pins are pulled down internally by default with 75K.