Important changes to forums and questions
All forums and questions are now archived. To start a new conversation or read the latest updates go to forums.mbed.com.
9 years, 5 months ago.
Connection to RJ45 connector
Hello everybody, for connecting the module to an Ethernet RJ45 connect, it is sufficient to connect the RD+, RD-, TD+ and TD- signals to a RJ45 connector with magnetics, right? If I have a RJ45 connector with LEDs, the LEDs must be driven by two GPIOs and managed by code, right? In the schematic of the module I see that there are two signals called LED_LINK and LED_SPEED going from the DP83848J to the LPC1768. What is the purpose of these signals? If their purpose is driving the LEDs on the RJ45 connector Is it possible to read their status by software for driving at the same value two GPIOs? Thank you for your attention.
Question relating to:
1 Answer
9 years, 5 months ago.
For the data lines it is a straight connection, all the termination is on the mbed board. Most RJ45 sockets with magnetics also expose the transformer center tap connections, these are normally connected to 3.3V and then a capacitor in the 0.1uF region to ground.
Yes, the two signals from the Phy to the LPC1768 would normally be connected directly to the LEDs. If you connect the LEDs to GPIOs on the mbed then you can either connect them to the normal signals via software or put them to your own used e.g. rather than activity meaning raw network traffic it could be used to indicate that your software has received / sent data.