Custom EtherCAT device

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13 Jun 2023 17:43 #273500 by PCW
Replied by PCW on topic Custom EtherCAT device
The problem with that is that without local step generation hardware/software,
It would be no better than a parallel port performance wise.

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13 Jun 2023 17:50 #273501 by Tady
Replied by Tady on topic Custom EtherCAT device
I agree. For propper stepping an FPGA is usualy used. I know about the IOs but I never took a look at the possibilities. You probably configure those via the EEPROM

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13 Jun 2023 20:48 #273514 by rft
Replied by rft on topic Custom EtherCAT device
ok, I see, so for proper real time performance there would be distributed clocks running on the MCU or FPGA, synchronized over etherCAT.

still, for the price, parallel port performance would be nice for general purpose stuff, compared to the price of Ethercat hardware.
The chip needs a config file written in EEPROM, to put it in the Digital I/O mode.
I try and get some boards together for testing.

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13 Jun 2023 21:05 #273515 by Tady
Replied by Tady on topic Custom EtherCAT device
I'm not sure you can use the gpio for stepping. Maybe if Linuxcnc toggles the outout via ethercat. But that means that the maxinum frequency us going to be a little less than 1kHz. That is wayyy lower that LPT. You would be way better of with a cheap STM32f103 or even an arduino uno

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16 Jun 2023 05:47 #273679 by RDA
Replied by RDA on topic Custom EtherCAT device

Non of the MCU has EtherCAT support via hardware you always need to use an ASIC. Tipically it connects via SPI or QSPI. With an Application Specific Integrated Circuit you can use the MCU for exchanging the data with the master and soing other stuff whil minimizing latency and jitter on the bus itself. Because the ASIC is responsible to recieve the packets on one port and while extracting data it also forwards the packet to the output port for the next slave.
I succesfully made the slave and interfaced it with an analog servo.
I setup the machine so one turn of the motor represents 4mm of movement eith this I achived 14m/min speed vith 0.1mm error while moving. This was dons only with FF1 and P tunning. If I spet more time on this I could lower the error. The movement is smooth without any problems
 

Dont say ”non” when there are chips that have ethercat and mcu in the same chip. I mean its only a handful of those but they do exist, example TI has the AM335X and Asix makes the AX58X00.
The TI is overkill for small projects but the Asix chips look nice on paper. But nobody knows where to get them.

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16 Jun 2023 05:49 #273680 by RDA
Replied by RDA on topic Custom EtherCAT device

ok, I see, so for proper real time performance there would be distributed clocks running on the MCU or FPGA, synchronized over etherCAT.

still, for the price, parallel port performance would be nice for general purpose stuff, compared to the price of Ethercat hardware.
The chip needs a config file written in EEPROM, to put it in the Digital I/O mode.
I try and get some boards together for testing.


As far as I remember you need to also set it to IO mode using the bootstrap resistors.

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16 Jun 2023 06:01 #273681 by Tady
Replied by Tady on topic Custom EtherCAT device
Ok sorry it seems there are MCUs that support Ethercat from hardware point of view. But still this chips are for professional use. I'm a hobby electronic and the first hurdle would be soldering the BGA package. And I have only experience with STM32 and AVR. And I see that one MCU costs 20 dollars

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16 Jun 2023 13:16 #273696 by PCW
Replied by PCW on topic Custom EtherCAT device
The LAN9255 is in a TQFP package

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16 Jun 2023 14:17 #273700 by Tady
Replied by Tady on topic Custom EtherCAT device
I was talking about the AM335X. I'm using the QFN package, and with the new board I will use the TQFP

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16 Jun 2023 16:20 - 16 Jun 2023 16:41 #273706 by RDA
Replied by RDA on topic Custom EtherCAT device
The asix one is not a BGA, they come in LQFP package.
Hats off to the person that finds a place where you can buy these. They look pretty ideal for this kind of stuff, check example the AX58100 www.asix.com.tw/en/product/IndustrialEthernet/EtherCAT/AX58100

Edit: Seems you can get these from aliexpress, or something claimed to be the chip at least. Under 15$ for a mcu with ethercat doesnt seem too bad.
Last edit: 16 Jun 2023 16:41 by RDA.

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