DuetWiFi Lash-Up

I recently grew weary of messing with the mightyboard in my printer more than I was printing. Looked around for an alternative and really like the DuetWiFi. It then occurred to me that I already have the stuff to lash one up from parts. Well, sort of... No TCM2660 stepper drivers, but it looks like a properly set up DRV8825 stepstick will work as long as I don't try to adjust the current through software. The main problem is the processor - an Atmel Cortex-M4 on the DuetWiFi, and an M-3 on the Arduino Due I'd be using. Same genus, different species. Anybody know if the firmware will run as is on the M3 chip, or maybe with a recompile for the M3, or maybe fugetaboutit? (I would have found the FPU in the M4 impossible to resist.)

I guess you could do a firmware build that uses the SAM3X processor. One issue you may face is that the SD card is connected to the HSMCI pins of the processor to get high file upload speeds and to allow the main SPI bus to be dedicated to the WiFi interface, but I'm not sure that the Arduino Due makes the HSMCI pins available.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I did some investigating and you are correct about the HSMCI pins. All of them are available except for MCDA0. Sadly, that pin was used exclusively to blink the TX LED. The LED could be removed and a wire run from it's cathode pad, I suppose; however, the main problem with the mightyboard I want to replace is noise. Gets into everything because of questionable board layout and inadequate decoupling (at least on the Chinese knockoff one that came in my printer). A spaghetti lash-up, now with a critical high speed data line running through a 30 gauge wire soldered to an LED pad, is sounding a bit dubious.

RRF does run on the Due, since there is a version for the RADDS.

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Giark
I did some investigating and you are correct about the HSMCI pins. All of them are available except for MCDA0. Sadly, that pin was used exclusively to blink the TX LED. The LED could be removed and a wire run from it's cathode pad, I suppose; however, the main problem with the mightyboard I want to replace is noise. Gets into everything because of questionable board layout and inadequate decoupling (at least on the Chinese knockoff one that came in my printer). A spaghetti lash-up, now with a critical high speed data line running through a 30 gauge wire soldered to an LED pad, is sounding a bit dubious.

If you want to reduce noise from the stepper motors, you can't beat the TMC2660 drivers. Numerous users have posted how quiet their printers have become since upgrading to the Duet WiFi.

Edited 1 time(s). Last edit at 01/07/2017 03:04PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

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dc42
If you want to reduce noise from the stepper motors, you can't beat the TMC2660 drivers. Numerous users have posted how quiet their printers have become since upgrading to the Duet WiFi.

They do look far better than the last generation of stepper drivers in a number of respects, interpolated microsteps included. However, I was referring to electrical noise rather than audible (I kind of like the C3P0-esk noises my printer makes:-) I don't think any of it's virtues are enough to overcome bad layout. I'd certainly prefer to use them in a home brew solution, but I've only found sources for the bare chips. The plated via PCB required for proper heat dissipation is beyond my home shop capabilities.

My interest is really in the WiFi capabilities of the DeutWiFi, the challenge of using junk I already have, while avoiding reinventing the firmware wheel. Making an exact copy of the board wouldn't be much fun. Pointless, in fact. If the project starts looking too much like what's already been done, it's best to buy a Duet and go on to other things.

You may find this thread interesting [forums.reprap.org]. It uses async comms instead of SPI to communicate with the ESP, so it's easy to hook up. But you don't get fast file upload, or file download (so no system files editor or height map visualisation either).

Edited 1 time(s). Last edit at 01/07/2017 06:29PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

It's a very interesting thread. Impressive that he did most of it in one night. Hope that degree he's getting is in CS or EE. It's shortcomings are a killer for me, though - I want to do everything from my PC through a web interface. There's another thread that briefly mentions the ESP32 that caught my attention, too. Can't seem to find it right now. It looks like it has enough horse power and I/O to run the whole shooting match all by itself. Dev boards are cheep, ~$20 even from US folks like sparkfun. Over the last few days I've been downloading various dev tools and docs for it and everything I've seen is pretty horrible. Bummer. I've ordered one anyway, so well see. The thought of writing firmware for it is daunting to me - I've not done any serious MC dev for years, and that was primarily assembly language on PICs.

@Giark: ESP32 is a very promising chip, I've been playing around with it now for a couple of days. I intend to turn it into a printer controller, but it needs a bit more time. For starters, the SPI driver is not yet in the official SDK.
One of the devs made a NES emulator for it, you can find a video on youtube about it. That uses an SPI LCD, and looking at the code.. well he wrote there all the SPI register settings by hand. He also mentioned on Hackaday that for example the external SRAM support is a bit glitchy for now, they need to work on that.
We will have to wait for a while until we can access all of its features (and documentation).

I personally didn't have any problem with the dev tools. If you follow the instructions for the official ESP-IDF, it works like charm.
I did not try the Arduino SDK for it, and I won't. It's just simply way far from an Arduino. Instead of it being helpful, the fake Arduino core just makes things more complicated. I see many negative comments from people who try to use it.

In this forum thread lhartmann is trying to create a FreeRTOS-based firmware for the ESP8266, which would also be good for the ESP32. Since there is no real printer firmware written in FreeRTOS, it is daunting indeed. I'm now looking at dc42's fork of RepRapFirmware to get a general idea of what should be done.

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Hubberthus
Since there is no real printer firmware written in FreeRTOS, it is daunting indeed.

These are the only references for 3d printer controllers that uses FreeRTOS:

Erik Zalm board based on STM32F4: I did not find any firmware for this, the Git repositories shows only a picture of the board. According to the following thread Erik Zalm board is used for Orca-XXL (commercial printer)

Makebed project: based on LPC1768 with links to Git repositories

Edited 1 time(s). Last edit at 04/04/2017 09:31AM by xebbmw.

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xebbmw

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Hubberthus
Since there is no real printer firmware written in FreeRTOS, it is daunting indeed.

These are the only references for 3d printer controllers that uses FreeRTOS:

Erik Zalm board based on STM32F4: I did not find any firmware for this, the Git repositories shows only a picture of the board. According to the following thread Erik Zalm board is used for Orca-XXL (commercial printer)

Makebed project: based on LPC1768 with links to Git repositories

RepRapFirmware for Duet WiFi and Duet Ethernet will be migrated to FreeRTOS within the next few weeks.

Edited 1 time(s). Last edit at 04/04/2017 02:13PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].