137 lines
7.3 KiB
Markdown
137 lines
7.3 KiB
Markdown
# MetalMusings EtherCAT device
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This repository contains the EtherCAT devices I have designed, built and put in use in linuxcnc.
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Everything should be here:
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- Schematics, PCB layouts, and what is needed to build the boards.
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- Software tools to create an ESI-file and program the ESC eeprom.
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- Software tools to create the application running on a STM32F407VG.
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- A big learning curve is hidden in here as well
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I have (so far) used two different ESC ICs: LAN9252 and Ax58100.
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Both work, I can't really see a difference.
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The Ax58100 has a leg spacing of 0.4 mm, 0.5 mm for the LAN9252, if that matters.
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On paper the Ax58100 has more builtin functionality like stepper motor drivers,
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but the documentation is lacking. Or my understanding of the documentation is lacking.
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The Ax58100 supposedly has more efficient access to registers and data.
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The indirection scheme is the main objection to using LAN9252, I have read.
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The LAN9252 is the true and tested IC of the two. If you don't know, go for the LAN9252.
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The EtherCAT cards, which I call EaserCAT cards, often use an EtherCAT chip and a normal MCU.
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I have used the STM32F407VGT6. The EaserCAT chip does the network talk and other
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EtherCAT things. The STM32 does the application things, like reading and setting pins high or low,
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reading encoder inputs, generate stepper motor pulses and other interesting applications one can think of.
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There is a narrow interface between the two: SPI and a couple of lines for synchronization.
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Any decent MCU can do that, it doesn't have to be a STM32F407VGT6. I have tested with a esp32 with success.
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Feel free to experiment with other processors.
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I learned most of what I know about EtherCAT through a number of Youtube Videos I made.
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There are accompanying git branches. For example, for video 8 you can check out the
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Video8 branch to get the software tree in the state at the video.
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More info on the videos, which are now more of historical interest, but also a bit of learning by following [this link](Videos.md)
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Here is the start of [building instructions](Build.md)
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## EaserCAT 2000 - a testbench for ESC+MCU, SOES, stepper generator, linuxcnc
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This was the first card that got used in Linuxcnc. Follow [link here](Cards/EaserCAT-2000/)
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I think I got it working pretty well in the end. There was, and still is, an issue with
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synchronization between the linuxcnc servo-loop and the ESC DC loop.
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I don't remember the status of it anymore, it was some time ago I worked with it.
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The main thing was that it lacked optocouplers and isolation for the external signals.
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## EaserCAT 3000 - All in one board with Ax58100
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This card is an evolution of the EaserCAT 2000 and was intended to be used in my plasma cutter.
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It features four stepper driver outputs, input for a THCAD arc voltage card, an encoder,
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an analog output (for spindle +- 10V), eight digital inputs, four digital outputs,
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plus some 12 I/O for any possible extension. The IOs are isolated from the MCU.
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However, I couldn't get this card to work, almost at all. The Ax58100 didn't even load the eeprom.
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Struggling with the documentation for the Ax58100, which formed my negative opinion about that,
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I gave up and let it sit for over half a year. It was first when someone came and asked
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questions around it I had another look. I built a new board, and it all started to work.
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At time of writing it all seems to work.
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[Link here](Cards/EaserCAT-3000-Digital-Stepper-Analog-Encoder-Frequency/)
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## EaserCAT 4000 - THCAD reader
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Faced with the problems with the EaserCAT 3000 board, and still wanting to use EtherCAT
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in my upcoming plasma cutter, I made this board whos single purpose is to read
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the PWM frequency from Mesa's THCAD board.\
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The THCAD board reads the voltage between
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the plasma torch and the workpiece which is around 100V. Highly isolated, and with
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a voltage to frequency converter it delivers a differential pwm signal.
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The frequency of this signal can be related to the voltage.\
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That's what is needed for linuxcnc torch height control.
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In the tests on the bench this can read at least up to 200 kHz, but its's better to be below 100 kHz.
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The THCAD has a frequency divider one can set to make the frequency range nicely match this.
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It seems to work fine so far.
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Implementation is with interrupts. \
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A better option would have been to use TIM2's PWM_INPUT function, which can work with several MHz frequency.
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I tried the PWM_INPUT method a lot but couldn't get it to work. The current method still works, though.
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If time and interests are in phase with the moon, I might look at PWM_INPUT again.
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This board is now relegated to history, replaced by the EaserCAT-6000.
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[Link here](Cards/EaserCAT-4000-THCAD-Reader/)
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## EaserCAT 5000 - Digital IO without MCU
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A card just doing Digital Input and Digital Output. The intentions were to read
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limit switches and some other switches around the plasma torch. And to switch on the plasma torch.
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It's a single LAN9252, configured for local IO. Optocouplers are attached to IO pins for isolation.
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It has been tested on the bench, it works with TwinCAT.
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HOWEVER, it doesn't work, and will not work, with linuxcnc. As I've learned,
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the IgH EtherCAT master needs a CoE client (CANopen over EtherCAT).
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The LAN9252 in DIO mode is only an EtherCAT client and can't be turned
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into a CoE client. And the IgH EtherCAT application interface for real-time
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communication can not be downgraded to work with a pure EtherCAT client,
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it requires a CoE client.
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To add CoE functionality means to add number of objects at certain positions
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in the client and that can not be done to the LAN9252. It is what it is.
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In a setup with LAN9252 with MCU, those objects are created in the firmware,
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so there it works.
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This board is now relegated to history, replaced by the EaserCAT-6000.
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## EaserCAT 6000 - Digital IO and frequency input
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Finally, a card that's actually used in a real system. This card is used in my plasma cutter.
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It has 12 digital inputs, 4 digital outputs and a frequency counter to get
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the input from Mesa's THCAD (reader of voltage between plasma nozzle and workpiece).\
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All digital IOs are opto-isolated and the frequency input uses a RS-485 receiver.
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In the plasma cutter, it does the job. There are three ECT60 stepper motor drivers.
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And the EaserCAT-6000 card. It handles limit switches for X, Y and Z, floating switch,
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break-away switch, and plasma Arc OK signal. There is room for e-stop and other switches.\
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The plasma torch is switched on using one of the digital outputs.\
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THCAD is an older model with full voltage input. Frequency divider is set to 1/32.
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This board replaces EaserCAT-4000 and EaserCAT-5000.
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[Link here](Cards/EaserCAT-6000-THCAD-reader+Digital-IO/)
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A few weeks later and I've used this card in the plasma cutter for quite a bit of cutting and it hasn't missed a beat. Works so well. THC follows the sheet surface up and down. Awesome.
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### License
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Don't violate the original licenses. No warranties. Use it any way you like.\
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Remember: It is a hobby project, not a product.
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