HOW TO MAKE W5100 MODULE WORK WITH SD CARD MODULE?

Some people may find out our W5100 module can`t work with SD card module at the same time, you can`t read/write any data from/to SD card.

Here is an solution for that. According to the schematic of our W5100 module, the SEN pin is always pulled up by 10K resistor. 

You may refer to the schematic part of this project for help.

That means the SPI of W5100 has always been enabled. So it might affect the communication between the MCU and the other SPI device.

Now you can solder the SEN pin to the CS pin of SD card slot. And set the CS pin of SD card socket to high voltage before you communicate with W5100 module. It will fix this problem.