details
In previous post, I explained the reason we need to use external Ethernet chip (W5500) to achieve hard-reatime EtherCAT Master on RPI. This post describes how to use W5500 module and Raspberry pi to make your own EtherCAT master controller which we call PiCAT
DIY Hardware (test only, not recommended for serious applications)
W5500 is an embedded Ethernet controller by Wiznet supporting only SPI communication up to 80 MHz. Although W5500 is designed as Hardwired TCP/IP controller, it also supports raw Ethernet frame (called MACRAW mode) which is ideal for EtherCAT communication development. W5500 is quite low cost compared to its functions.
For demonstration I will use a popular W5500 module which is very easy to find on internet. You may just need to visit Ebay or Amazon and search for W5500, pick one and follow instruction here to have your own RPI EtherCAT Master. There may be a little bit difference among many W5500 modules, but almost them will have common interface pins:
- Power supply include GND and 5V or 3.3V, or both
- RST for resetting W5500
- SPI CS, chip select line for SPI communication
- SPI SCLK, clock source for SPI
- SPI MOSI
- SPI MISO
documents
Code
soem-w5500-rpi 
Others
Xenomai 3
XMC4800 Relax Kit
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