Custom EtherCAT device

they have c2000 dev boards starting at $49, with ethercat onboard and a entire rtos library with encoder i2c etc for those boards.

check mouser and digikey

look at the launchxl boards they are designed specifically for robotics motor control etc.

Code:

Tady post=272254 userid=23955I'm in early stages of coding this but I did some measurements of the time it takes and I couldn't get it under 1ms.. More like 1.7ms cycle time.. I did try overclocking the SPI from 18MHz to 36MHz and there wasn't any improvement... I will try a different IC just fir the heck of it. The LAN IC dies support up to 50MHz. I'm curently using pooling mode for testing, but I did see different projects that tried using DMA but were unsuccessful ..

There is something very wrong with the implementation if this is truly the results you experienced. I went to an Ethercat seminar recently and it can handle 1000 I/0's in 30 usec

smc.collins wrote:

they have c2000 dev boards starting at $49, with ethercat onboard and a entire rtos library with encoder i2c etc for those boards.

check mouser and digikey

look at the launchxl boards they are designed specifically for robotics motor control etc.
 

This sounds interesting. I searched through digikey for stuff in stock but I wasn't able to find anything. Would you mind linking to a product?

These are 2 different things, communicating with an ethercat slave controller from a mcu and checking a state of an input through the ethercat bus. These should not be mixed together. As even using example the LAN9252 or the Asix/TI chips would perform very differently. One is just a chip that handles the ethercat layer and you need to access through SPI and the 2 other have the ethercat layer and MCU's in the same chip.
Im sure the LAN9252 is also very fast if bootstrapped to IO mode, but its probably the slowest from all if you pair it with a MCU.

In any case the process data transfer time should not be terribly
significant relative to a normal servo thread time even with a LAN9252/53.

In SPI mode and 50 MHz clock you get about 6 MB/s transfer
so only about 16 usec for 100 bytes in indexed mode
This drops to 4 usec in QSPI mode and 2.5 usec in 16 bit bus mode

Yea I'm aware of that. I would really just like to bring the SPI transfers down to under 1ms, so the data is "as fresh as possible". The LAN chip does all the Ethercat specufic stuff for us and it is fast. I checked with wireshark and there is no siginifican delay between packets. They get returned very fast, so that works