yunjin544 / soem4arduino

Simple Open EtherCAT Master Library for Arduino

Simple Open EtherCAT Master Library for Arduino

This is SOEM (Simple Open EtherCAT Master) library ported for Arduino.

It's just for educational or experimental purposes.

The original SOEM is at https://github.com/OpenEtherCATsociety/SOEM

Supported hardware

• Arduino Due + Ethernet Shield 2 (W5500)
• ESP32 + WIZ850io (W5500)
• M5Stack + M5Stack LAN Module (W5500)
• M5 ATOM Matrix + WIZ850io (W5500)
• GR-SAKURA (Renesas RX63N)
• GR-ROSE (Renesas RX65N)
• chipKIT Max32 (PIC32MX) + Ethernet Shield 2 (W5500)

limitations

Many of MCUs don't have large memory, and has only one LAN port. SOEM4Arduino reduces memory usage, and does not support redundant LAN ports.

Doe to reducing memory usage, some functions are limited.

item	constant name	original SOEM	SOEM4Arduino
max entries in Object Dictionary list	EC_MAXODLIST	1024	64
max entries in Object Entry list	EC_MAXOELIST	256	64
max number of slaves in array	EC_MAXSLAVE	200	64
number of frame buffers	EC_MAXBUF	16	2

Notes for ESP32

Connect ESP32 and W5500 as shown below.

ESP32-DevKitC	WIZ850io (W5500)
GND	GND
3V3	3.3V
IO23 (VSPI MOSI)	MOSI
IO19 (VSPI MISO)	MISO
IO18 (VSPI SCK)	SCLK
IO5 (VSPI SS)	SCSn

However, M5Stack's SS is not IO5 but IO26.

Notes for M5 ATOM Matrix

M5 ATOM Matrix's IO pins are remappable. The pin assignment is determined as follows. It's just for ease of wiring.

M5 ATOM Matrix	WIZ850io (W5500)
GND	GND
3V3	3.3V
IO21	MOSI
IO19	MISO
IO25	SCLK
IO22	SCSn

Please choose ESP32 Pico KIT as the board configuration, and use 115200 for the baud rate.

Notes for GR-ROSE

You must create a user task to use SOEM.

GR-ROSE's main task (setup & loop) has only 512 byte stack. On the other hand, SOEM uses more than 3k byte local variables. Therefore the memory corruption will occur when you call SOEM's API on the main task. You must creat a task with more than 4k byte stack and then call SOEM's API on the task. Please see the sample sketch (slaveinfo.ino).

Documentation of original SOEM

See https://openethercatsociety.github.io/doc/soem/

Article about this library (written in Japanese)

See https://lipoyang.hatenablog.com/entry/2019/08/13/125008