Ethernet Shield (Wiznet W5100) for Arduino
The Arduino Ethernet Shield is an ethernet shield that is prepared and produced based on the circuit diagram provided by Arduino. It is fully compatible with the original Arduino Ethernet Shield and all libraries and codes prepared for it can be used with this shield as well. By using the Arduino Ethernet Shield, you can connect your Arduino board to the internet in just a few minutes. Simply plug the shield into the Arduino, connect the RJ45 cable to the Ethernet Shield, and follow a few steps to start controlling your Arduino over the internet.
The Arduino Ethernet Shield allows you to connect to the internet over Ethernet. Based on the Wiznet W5100 chipset, this shield is compatible with both TCP and UDP protocols. The Arduino Ethernet Shield supports 4 simultaneous socket connections. By connecting an Ethernet cable to the standard RJ45 Ethernet socket on the shield, you can quickly connect your Arduino to the internet using the Ethernet Library.
Arduino Ethernet Shield has an SD card slot. This allows you to write and read various information to and from the SD card, which can be used with the SD Library. The SD card's SS pin is on pin 4.
Arduino communicates with the Wiznet W5100 processor and the SD card through the SPI bus. The pins for this are 11, 12, and 13 on the UNO and 50, 51, and 52 on the MEGA. On both models, pin 10 is the W5100 selection pin and pin 4 is the SD card selection pin. These pins are not used as general input/output pins. On the Arduino MEGA, the hardware SS pin (pin 53) is not used for the SD card or W5100, but it must be set as an output pin.
An important point to remember is that W5100 and SD card use the same SPI bus, so only one of them can be active at a time. If both communications are desired at the same time, attention must be paid to the library used being shared. If you are not going to use both at the same time, you need to make the unused part passive. To make the SD card passive, you need to make the 4th pin an output and output 5V (high) from this pin. To make the W5100 passive, set the 10th pin as an output and output 5V (high) from this pin.
Note: You can check out the Arduino Ethernet product for the integrated version of Uno with Ethernet Shield.