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Low cost 32-bit controller board

Posted by dc42 
Re: Low cost 32-bit controller board
February 23, 2015 08:38AM
Quote
dc42
Screw terminals are nice for anyone who designs and builds a printer from scratch and doesn't want to pay £20 or so for for a crimp tool. For kit makers and anyone with a crimp tool, plug-in connectors are better. The kit manufacturers benefit by reducing the possibility of miswiring, and.users benefit from being able to disconnect the wiring from the electronics quickly and easily (and again reducing the possibility of miswiring when they reconnect). I removed most of the screw terminal blocks from a Duet board I received and replaced them with header pin strips, to make the wiring of my Mini Kossel easier. I'm not sure whether to go for pin headers to keep the cost down, or locking/polarised Molex connectors that cost a little more. For anyone who really wants to use screw terminals, I guess I could offer a board with the connectors not fitted. I do plan to use screw terminals for the heated bed, hot end heaters and power connections.

I like this attitude. And also favour Molex KK over plain pin strips for the reason you mentioned: disconnect, connect and be sure it works the same as before. Crimp pins get soldered here, works fine without a crimp tool.


Generation 7 Electronics Teacup Firmware RepRap DIY
     
Re: Low cost 32-bit controller board
February 23, 2015 09:00AM
Quote
plankton
You might want to take note of the lesson from RAMPS-FD, don't publish the full schematic until the worst bugs have been worked out (RAMPS-FD was picked up by the clone makers, but they cloned the early beta version of the board).

I do hope we don't have to bend to the stupidity of eBay buyers. Wider collaboration is only possible with publishing. If that's a problem we shouldn't give up on collaboration, but find other measures to distinguish the good ones from the bad ones instead. As you probably know, I value collaboration very high and consider it to be essential for the success of a community.

Perhaps by putting some text like "unfinished" to the copper tracks until it's actually done. People dumb enough to copy something unfinished are also dumb enough to not remove such texts.


Generation 7 Electronics Teacup Firmware RepRap DIY
     
Re: Low cost 32-bit controller board
February 23, 2015 09:12AM
Quote
AndrewBCN
So, this project follows exactly the same paradigm as all the others that preceded it, and right now I don't see how dc42 can bring down the costs of a Duet board ($120 + shipping) to the same level as that of a RAMPS + Arduino combo (around $20, shipping included), by just changing the ARM processor, removing four Allegro chips that costs around $1 each, and using a double-sided PCB, since these small changes certainly won't decrease costs by more than $20 or so.

Andrew, you are complaining about the paradigm and not "thinking outside the box", but the only alternative one you have suggested is a Linux box plus an 8-bit microcontroller. I have pointed out that the 8-bit microcontroller you suggested actually costs more than twice the price of the ARM processor I propose to use. IMO this solution is also too complex for most 3D printer users, even though I can see it may appeal to computer geeks, RPi owners and the like, and might even save money if you have more than one printer and use the same Linux box to control them all.

A Duet won't cost you $120 + shipping, it will cost you $100 + shipping + any import tax you are liable for. Go to the Think3DPrint3D web site, look up the Duet and observe that it costs £78 including VAT. Customers outside the EU are not liable for VAT, so if you are in the USA then the price to you would be GBP65, which equates to USD100 at today's exchange rates.

The AZSMZ Mini already shows that it is possible to make a budget 32-bit board, because it sells for $60 + shipping. If it becomes popular and gets cloned, then I am sure the price will come down. The board I propose will have a lower parts cost than the AZSMZ Mini.

I take your point about most users being likely to prefer WiFi to wired Ethernet. It's actually very easy and inexpensive to convert a wired Ethernet port to wifi, using a device such as [www.ebay.co.uk]. But you've got me thinking about the possibility of a WiFi daughterboard.

Edited 3 time(s). Last edit at 02/23/2015 09:15AM by dc42.



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].
Re: Low cost 32-bit controller board
February 23, 2015 09:34AM
With RPi most people use a USB Wifi dongle, those are dirt cheap, but not sure how easy it would be to implement support for that (drivers, USB A port)?
Re: Low cost 32-bit controller board
February 23, 2015 10:16AM
Quote
dc42
...
Andrew, you are complaining about the paradigm and not "thinking outside the box", but the only alternative one you have suggested is a Linux box plus an 8-bit microcontroller. I have pointed out that the 8-bit microcontroller you suggested actually costs more than twice the price of the ARM processor I propose to use.

Actually you have to take into account the total cost of the boards, not the cost of the MCUs themselves, because nobody buys a surface mount AVR or ARM chip to use as such, we all buy boards with these and various other components already soldered (well, the vast majority of us do). So comparing the cost per unit of any two MCUs bought in 10k quantities is really irrelevant to any discussion about controllers here in this forum. It makes no difference if the 8-bit MCU costs $2.20 and the ARM MCU costs $1.30 or so, if at the end of the day the ARM board ends up costing $120 and the AVR board costs $20.

Quote
dc42
IMO this solution is also too complex for most 3D printer users, even though I can see it may appeal to computer geeks, RPi owners and the like, and might even save money if you have more than one printer and use the same Linux box to control them all.

Actually adding an OctoGoatBox (basically a 150mmx100mmx25mm Linux appliance with a single LED and a few connectors) to any 3D printer makes it much easier to use and much more practical too. And there is nothing extremely complex about setting up an OctoGoatBox, it only requires setting up an ESSID and password in a text file, so that it can connect securely to a WiFi network. I don't think that even remotely qualifies as "geek-only".

Quote
dc42
A Duet won't cost you $120 + shipping, it will cost you $100 + shipping + any import tax you are liable for. Go to the Think3DPrint3D web site, look up the Duet and observe that it costs £78 including VAT. Customers outside the EU are not liable for VAT, so if you are in the USA then the price to you would be GBP65, which equates to USD100 at today's exchange rates.

I live in Spain so I'll pay £78 ($120 at current exchange rates) + shipping ($16) = $136.

Quote
dc42
The AZSMZ Mini already shows that it is possible to make a budget 32-bit board, because it sells for $60 + shipping. If it becomes popular and gets cloned, then I am sure the price will come down. The board I propose will have a lower parts cost than the AZSMZ Mini.
I take your point about most users being likely to prefer WiFi to wired Ethernet. It's actually very easy and inexpensive to convert a wired Ethernet port to wifi, using a device such as [www.ebay.co.uk]. But you've got me thinking about the possibility of a WiFi daughterboard.

A network bridge or an add-on WiFi daughterboard are both likely to cost almost as much as a full-fledged OctoGoatBox and you still don't have the CPU power, RAM and storage required to drive a full-fledged Web interface such as OctoPrint.
That's the kind of half-baked "solution" that I definitely would not recommend.
Re: Low cost 32-bit controller board
February 23, 2015 10:22AM
Quote
plankton
With RPi most people use a USB Wifi dongle, those are dirt cheap, but not sure how easy it would be to implement support for that (drivers, USB A port)?

First you need to write the USB host driver, then the specific Wi-Fi dongle driver, then the Wi-Fi helper user space utilities, then the Wi-Fi protocol support, then the TCP/IP stack. Easy... not!

The WiFi daughterboard that dc42 mentions includes a dedicated MCU with all this already programmed and debugged... however it costs almost as much as an OctoGoatBox.
Re: Low cost 32-bit controller board
February 23, 2015 11:06AM
Quote
AndrewBCN
A network bridge or an add-on WiFi daughterboard are both likely to cost almost as much as a full-fledged OctoGoatBox and you still don't have the CPU power, RAM and storage required to drive a full-fledged Web interface such as OctoPrint.
That's the kind of half-baked "solution" that I definitely would not recommend.

1. You obviously didn't follow the link to the network bridge I linked to. It's only GBP12, and that's shipped from the UK. You can probably get it even cheaper if you buy it from China.

2. The Duet + RepRapFirmware shows that you don't need a massive amount of CPU power to provide an excellent web interface. Having a wifi daughterboard with on-board processor to manage the TCP/IP stack would mean that the processor I plan to use for the low cost 32-bit board would be adequate.

3. I didn't mention a specific WiFi daughterboard. I guess you are thinking of the Arduino one, which is massively overpriced IMO.

So, thanks for pointing me in the right direction! All I need to add to my low-cost 32-bit board is a connector for a WiFi module such as this one [www.ebay.co.uk]. The wifi module costs so little that this solution will still cost a lot less than a controller board with built-in wired Ethernet.

Edited 1 time(s). Last edit at 02/23/2015 11:07AM by dc42.



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].
Re: Low cost 32-bit controller board
February 23, 2015 12:10PM
Quote
dc42
Quote
AndrewBCN
A network bridge or an add-on WiFi daughterboard are both likely to cost almost as much as a full-fledged OctoGoatBox and you still don't have the CPU power, RAM and storage required to drive a full-fledged Web interface such as OctoPrint.
That's the kind of half-baked "solution" that I definitely would not recommend.

1. You obviously didn't follow the link to the network bridge I linked to. It's only GBP12, and that's shipped from the UK. You can probably get it even cheaper if you buy it from China.
That is probably a MIPS appliance running some derivative of OpenWRT, so you would still need to run a TCP/IP stack on your controller board. And for more or less the same price I could buy a TP-Link WiFi router with 4+1 ethernet ports here in Spain through Amazon, no need to go on eBay or order from China. And the TP-Link router at least comes with a power brick, this dongle requires a +5V source of some kind as far as I can tell... Again, imo that's a half baked "solution".

Quote
dc42
2. The Duet + RepRapFirmware shows that you don't need a massive amount of CPU power to provide an excellent web interface. Having a wifi daughterboard with on-board processor to manage the TCP/IP stack would mean that the processor I plan to use for the low cost 32-bit board would be adequate.

Not sure what you call "an excellent web interface", so a screenshot would be nice.

Quote
dc42
3. I didn't mention a specific WiFi daughterboard. I guess you are thinking of the Arduino one, which is massively overpriced IMO.

So, thanks for pointing me in the right direction! All I need to add to my low-cost 32-bit board is a connector for a WiFi module such as this one [www.ebay.co.uk]. The wifi module costs so little that this solution will still cost a lot less than a controller board with built-in wired Ethernet.

So, by the time you have successfully interfaced the WiFi module to your controller electronics, you'll have two 32-bit MCUs onboard, you'll have Wi-Fi connectivity as I had suggested above, and you'll still have nothing such as the OctoGoatBox that can run heavy duty calculations, a slicer program or an excellent web interface (OctoPrint) with video, etc...
Re: Low cost 32-bit controller board
February 23, 2015 07:12PM


I wonder if you have noticed the 8pin socket of LCD board. This is inserted WIFI module ESP8266 place.

Edited 1 time(s). Last edit at 02/23/2015 07:23PM by cxandy.


New 32 bit ARM based Motion controller for 3D printers, CNC Machines and Laser cutters. Like Azteeg x5 mini or smoothieboard(no network).
AZSMZ Mini [www.ebay.com] [bancuit.aliexpress.com]
AZSMZ 12864 LCD [www.ebay.com] [bancuit.aliexpress.com] [azsmz.aliexpress.com]
SMART RAMPS [www.ebay.com] [bancuit.aliexpress.com] [azsmz.aliexpress.com]
[www.facebook.com]
Re: Low cost 32-bit controller board
February 23, 2015 07:44PM
Quote
cxandy
I wonder if you have noticed the 8pin socket of LCD board. This is inserted WIFI module ESP8266 place.

No, I hadn't noticed. Nice! I wonder whether RepRapFirmware could be run on that board...



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].
Re: Low cost 32-bit controller board
March 23, 2015 10:38PM
If I install a ESP8266 wifi module on my amsmz mini LCD board, can I use the Smoothie web interface?
If not, how is the ESP8266 used?

Thanks!
Re: Low cost 32-bit controller board
March 24, 2015 05:02PM
So, also my 2 (euro)cent`s for this project grinning smiley

where should i start? hmm.

Maybe as a lowcost alternative, the basic board should maybe start with really just the basics:
4 Stepper driver sockets / Singe Extruder version (maybe also a version with soldered chips?)
No-SD Card slot (who is using this without a LCD at all?)
Micro-USB connector
small size, this year will be the year of small printers, so best would be if there is also a small board available (maximum the size of a Sanguino, even smaller would be better grinning smiley )

if someone wants to have more features you can add "Upgrades" via the expansion header (which will then be pretty with lots of pins grinning smiley )
* a simple Extension board for up to 1-2 addition steppers/heaters/thermistors, maybe also a additional PWM Fan controller on it.
Then also people with more Extruders can run it, but in my optionion the large ammount of people still only print with one Extruder.

* LCD with SD-Card, maybe a small standard version (the radds lcd is really nice and tiny), and Graphics version.

Molex KK system would be great, as Traumflug already mentioned it, i also us this on all projects, the work perfect when soldered not crimped smiling smiley

Chri

Edited 2 time(s). Last edit at 03/24/2015 05:09PM by Chri.


[chrisu02.wordpress.com] Quadmax Intel Delid Tools
Re: Low cost 32-bit controller board
March 25, 2015 02:18AM
check this
taobao
Re: Low cost 32-bit controller board
March 25, 2015 08:34AM
They are calling it the "Red Rabbit" board:

http://www.3dxmy.com/?p=822

No sense of how they stand on open-source, but a huge concern that the firmware was apparently developed in-house and obviously has a lot of custom code to run the color touchscreen. On the plus side, the top-of-the-line board with a larger touchscreen and dual hotends is under $73 at today's exchange rate.....
Re: Low cost 32-bit controller board
March 25, 2015 11:55AM
Quote
vreihen
They are calling it the "Red Rabbit" board:

http://www.3dxmy.com/?p=822

No sense of how they stand on open-source, but a huge concern that the firmware was apparently developed in-house and obviously has a lot of custom code to run the color touchscreen. On the plus side, the top-of-the-line board with a larger touchscreen and dual hotends is under $73 at today's exchange rate.....

If you don't have the source code or even if you do manage somehow to get your hands on the source code, but all the comments are in Chinese and/or it's not clean, easy to read the code, then it makes for a $73 paperweight. thumbs down
Re: Low cost 32-bit controller board
April 05, 2015 10:53AM
I still have this project going on the back burner. Schematic capture is nearly complete, and the most important parts of the PCB layout are done. Here is the specification:

Size: 100mm x 80mm x 22mm.
Processor: 32-bit ARM Cortex M3, 64MHz clock speed, 256K flash, 48K RAM.
Power input: 12 to 30V. On-board 5V regulator, with provision for attaching a heatsink to allow high-current devices on the 5V output e.g. TFT screen.
Stepper drivers: 5 sockets accepting either standard Stepstick-type drivers, or modified Stepstick drivers with digital control of stepper motor current, or a mixture of both. Dual Z motor connections.
On-board SDHC card socket.
I/O:
- Native USB port (not serial-over-UScool smiley
- 16A heated bed output (I might be persuaded to make this 20A)
- Two 6A extruder heater outputs
- One 2A controllable fan output
- One permanent fan output (for hot end fan)
- Three endstop inputs
- 4-pin Z-probe connector, to suit just about any kind of Z probe
- Expansion connector with 11 I/O pins + power including UART, SPI, TWI. Uses include connecting PanelDue colour touch screen (uses 2 pins), or connecting 12864 mono GLCD + rotary encoder (uses 6 pins).
LEDs: one per heater, one for the controllable fan, one per endstop, one to indicate 5V power.
BOM cost (1000 off): approx. 75% of BOM cost of Arduino Mega + RAMPS.
Assembly cost: less than Arduino Mega + RAMPS.
Target selling price for first batch: GBP39/USD59 excluding VAT/sales tax.
Firmware: I will port RepRapFirmware to it. This is 32-bit firmware supporting Cartesian, CoreXY and Delta printers, with digital control of stepper motor current, flexible configuration using gcodes and gcode macro files (no need to rebuild and upload the firmware to change configuration), segmentation-free delta movement, fast delta calibration in a single iteration, and many other advanced features. If the board takes off, then I guess others will port 32-bit Marlin to it if there is enough demand.

The question I have is: is there enough interest in the board for me to justify having 100 manufactured; or would I end up with a lot of unsold stock?



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].
Re: Low cost 32-bit controller board
April 05, 2015 11:23AM
@KDan & cxandy

I took some time to check the ESP8266 WiFi modules that are now available for around $3 from China and I have concluded for many reasons that they are not really fit for use to provide a WiFi connection for 3D printer controllers. They are really designed for IoT use and the bandwidth and latency they provide are geared for that kind of application. Besides that, I would describe them as "experimental devices", and would require considerable time and effort to interface (in software) to any of the existing RepRap firmwares.
Re: Low cost 32-bit controller board
April 05, 2015 11:32AM
I have completed part of the test, repetier host 1.06 and smoothieboard connectivity, when printing at present no problems found now.


New 32 bit ARM based Motion controller for 3D printers, CNC Machines and Laser cutters. Like Azteeg x5 mini or smoothieboard(no network).
AZSMZ Mini [www.ebay.com] [bancuit.aliexpress.com]
AZSMZ 12864 LCD [www.ebay.com] [bancuit.aliexpress.com] [azsmz.aliexpress.com]
SMART RAMPS [www.ebay.com] [bancuit.aliexpress.com] [azsmz.aliexpress.com]
[www.facebook.com]
Re: Low cost 32-bit controller board
April 05, 2015 01:09PM
@dc42 You might want to look at this Kickstarter to compare features and price:

[url=https://www.kickstarter.com/projects/1177488680/bbp-making-your-3d-printer-faster /url]
Re: Low cost 32-bit controller board
April 05, 2015 03:24PM
Quote
veng1
@dc42 You might want to look at this Kickstarter to compare features and price:

[www.kickstarter.com]

Looks interesting, however it is a high-end board, like Duet/Smoothieboard/Alligator but with a higher-end processor and even more I/O. I'm looking to produce something that is fairly basic (but dual-extruder capable) and cheap enough eventually to replace Arduino/RAMPS. They haven't quoted a target price, but I expect it would be quite high, probably higher even than Smoothieboard.

Edited 1 time(s). Last edit at 04/05/2015 03:24PM by dc42.



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].
Re: Low cost 32-bit controller board
April 05, 2015 06:28PM
Quote
dc42
They haven't quoted a target price, but I expect it would be quite high, probably higher even than Smoothieboard.

If you look at the rewards, then you can get the BBP Board for $79 and the BBP 1S for $99
Re: Low cost 32-bit controller board
April 05, 2015 08:21PM
Quote
cxandy
I have completed part of the test, repetier host 1.06 and smoothieboard connectivity, when printing at present no problems found now.

Really I would be curious about a few details of your implementation.

For example the serial baud rate (since the ESP8266 only provides a serial connection). From what I have read it is limited to 57600 baud, about 1/5 the baud rate of Marlin on an AVR Arduino.

Also have you measured the latency for a single G-code command sent from the host PC to the smoothieboard ? Because by the time we have gone through the TCP/IP stack in the host, whatever latency the LAN adds, then the TCP/IP stack in the ESP8266, then serial conversion to send the command to the smoothieboard, I am guessing we are adding somewhere on the order of tens of milliseconds - that basically rules out this solution for 3D printing, imho.

Do you do any buffering in the very limited RAM available in the ESP8266? Did you manage to program any application in the ESP8266 or are you using it as a dumb serial to wifi converter?
Re: Low cost 32-bit controller board
April 05, 2015 08:36PM
Quote
JustAnotherOne
Quote
dc42
They haven't quoted a target price, but I expect it would be quite high, probably higher even than Smoothieboard.

If you look at the rewards, then you can get the BBP Board for $79 and the BBP 1S for $99

The way I see it, they seem to have the hardware pretty much ready, and the Linux frontend is not a problem (I have Linux with OctoPrint running on a 1GHz Cortex A8 processor right here and I use it everyday for 3D printing, so I know it can be done), on the other hand there is zero information and/or source code available to show that they have indeed a solution to control the steppers using the PRUs, a motion planner (there is a sketch, that's all as far as I can see), etc...

So: another possible paperweight, this one costs $79 + $21 shipping i.e. $100 vs. $73 for the "Red Rabbit" paperweight vs. $1XX for a Smoothieboard, which is definitely not a paperweight. Conclusion: if I were shopping for a ready-to-run 32-bit controller I would definitely go for the Smoothieboard these days, even though it "locks you in" with a single firmware and a single supplier.

If dc42 can come up with something that is 1/2 the price of a Smoothieboard I believe there is a niche for it, specially if it is sufficiently well documented so that Marlin, Repetier, Smoothie and other firmwares can be ported to it.

Edited 1 time(s). Last edit at 04/05/2015 08:44PM by AndrewBCN.
Re: Low cost 32-bit controller board
April 05, 2015 08:55PM
Quote
dc42
I still have this project going on the back burner. Schematic capture is nearly complete, and the most important parts of the PCB layout are done. Here is the specification:

Size: 100mm x 80mm x 22mm.
Processor: 32-bit ARM Cortex M3, 64MHz clock speed, 256K flash, 48K RAM.
Power input: 12 to 30V. On-board 5V regulator, with provision for attaching a heatsink to allow high-current devices on the 5V output e.g. TFT screen.
Stepper drivers: 5 sockets accepting either standard Stepstick-type drivers, or modified Stepstick drivers with digital control of stepper motor current, or a mixture of both. Dual Z motor connections.
On-board SDHC card socket.
I/O:
- Native USB port (not serial-over-UScool smiley
- 16A heated bed output (I might be persuaded to make this 20A)
- Two 6A extruder heater outputs
- One 2A controllable fan output
- One permanent fan output (for hot end fan)
- Three endstop inputs
- 4-pin Z-probe connector, to suit just about any kind of Z probe
- Expansion connector with 11 I/O pins + power including UART, SPI, TWI. Uses include connecting PanelDue colour touch screen (uses 2 pins), or connecting 12864 mono GLCD + rotary encoder (uses 6 pins).
LEDs: one per heater, one for the controllable fan, one per endstop, one to indicate 5V power.
BOM cost (1000 off): approx. 75% of BOM cost of Arduino Mega + RAMPS.
Assembly cost: less than Arduino Mega + RAMPS.
Target selling price for first batch: GBP39/USD59 excluding VAT/sales tax.
Firmware: I will port RepRapFirmware to it. This is 32-bit firmware supporting Cartesian, CoreXY and Delta printers, with digital control of stepper motor current, flexible configuration using gcodes and gcode macro files (no need to rebuild and upload the firmware to change configuration), segmentation-free delta movement, fast delta calibration in a single iteration, and many other advanced features. If the board takes off, then I guess others will port 32-bit Marlin to it if there is enough demand.

The question I have is: is there enough interest in the board for me to justify having 100 manufactured; or would I end up with a lot of unsold stock?

hmm, for me unfortunatley this doesn`t sound like a low-cost board anymore, also a little bit too large for my small printers.
i`l probably have to stay further with sanguino`s sad smiley

Chri

Edited 1 time(s). Last edit at 04/05/2015 08:55PM by Chri.


[chrisu02.wordpress.com] Quadmax Intel Delid Tools
Re: Low cost 32-bit controller board
April 05, 2015 09:16PM
Quote
AndrewBCN
@KDan & cxandy

I took some time to check the ESP8266 WiFi modules that are now available for around $3 from China and I have concluded for many reasons that they are not really fit for use to provide a WiFi connection for 3D printer controllers. They are really designed for IoT use and the bandwidth and latency they provide are geared for that kind of application. Besides that, I would describe them as "experimental devices", and would require considerable time and effort to interface (in software) to any of the existing RepRap firmwares.

I agree, the bandwidth is disappointing (not sure about the latency, I haven't measured it yet); but adequate for getting status updates and controlling the printer (just as PanelDue already does, at 57600 baud). I understand that with the right firmware, it runs at 250K baud. Even so, you probably wouldn't want to load the entire web interface over it; but it would be possible to load the interface from a local web server running on the user's PC or RPi etc. and connect to the printer over WiFi. You could even upload files to the SD card if you didn't mind the upload speed being rather slow (but probably no slower than uploading to Arduino/RAMPS over USB, if the 250kbaud can be maintained). I'm also wondering whether it would be possible to change the firmware to use SPI instead of async serial.

Quote
AndrewBCN
Conclusion: if I were shopping for a ready-to-run 32-bit controller I would definitely go for the Smoothieboard these days, even though it "locks you in" with a single firmware and a single supplier.

There are other options too, such as the Duet, which costs less than the Smoothieboard if you don't need dual extrusion, but has similar features. It's fully open-source, and although it currently runs only one firmware, there are 2 well-maintained forks of that firmware as well as the master. One of them (mine) is the only open-source firmware that can do full 7-factor auto-calibration of a delta printer quickly, in one iteration, taking less than 30 seconds.



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].
Re: Low cost 32-bit controller board
April 06, 2015 05:24PM
Good work dc42.

I'm ready for 32bit, but for me I'd really want to have max endstops as well.

20A heatbed option would be a good move if it didn't load the price too much.

I agree with the earlier comment from Chri about an on board SD card. Most people would go with a smart LCD controller with a card reader built in, and I think the main board and wiring should be away from everyday finger poking.

-a
Re: Low cost 32-bit controller board
April 06, 2015 06:01PM
Alan, thanks for your feedback.

Regarding endstops, I believe very few people use more than one endstop per axis, so I don't want to dedicate another 3 I/O pins to a second set of endstops. Would it be acceptable to make some of the pins on the expansion connector available for additional endstops?



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].
Re: Low cost 32-bit controller board
April 07, 2015 05:43AM
Quote
dc42


The parts cost is less than £15 including PCB. Assembling it in the UK would be uneconomic because of the large number of through-hole parts (i.e. the connectors), so it would have to be assembled in China. I'll get some quotations when the Chinese New Year is over. The initial selling price I had in mind was about £35, but if the production volume became high enough then sub-£30 + shipping + tax (where applicable) should be achievable.

.

Only just spotted this thread so probably a bit late to come to the party but
regarding assembly costs above , would it be feasible to supply boards with any SMDs already assembled but leave the user to fit the through hole components
Would the saving in assembly costs leave enough maybe to fit ethernet into the design?

Don
Re: Low cost 32-bit controller board
April 07, 2015 06:06AM
Quote
Don Recardo
Quote
dc42


The parts cost is less than £15 including PCB. Assembling it in the UK would be uneconomic because of the large number of through-hole parts (i.e. the connectors), so it would have to be assembled in China. I'll get some quotations when the Chinese New Year is over. The initial selling price I had in mind was about £35, but if the production volume became high enough then sub-£30 + shipping + tax (where applicable) should be achievable.

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Only just spotted this thread so probably a bit late to come to the party but
regarding assembly costs above , would it be feasible to supply boards with any SMDs already assembled but leave the user to fit the through hole components
Would the saving in assembly costs leave enough maybe to fit ethernet into the design?

Don

Yes, that would be possible, however I think it might reduce the appeal as well as making it impossible to ship them fully tested. But it would make it practical for me to order a smaller batch (e.g. 50) and get them assembled in Scotland, as my other boards are.

Regarding Ethernet, I'm looking to support the ESP8266 wifi module. The bandwidth of this module is unfortunately rather low, so loading the initial web page from the board for the first time would take 30+ seconds. But browser caching will probably reduce this to an acceptable time. Alternatively, the web files could be mostly fetched from a local web server or the Internet, as RepRapPro used to do for the Ormerod.



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].
Re: Low cost 32-bit controller board
April 07, 2015 07:03AM
Thanks for the reply Dave

I for one would be happy to fit the through hole parts to save a bit more money

I shall follow this thread with interest

Don
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