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ESP32 Printer Board

Posted by CthulhuLabs 
Re: ESP32 Printer Board
January 07, 2018 02:26PM
Did you mean 12v IN 24V OUT for the motors using DC-DC boost converter? It would be nice if it worked since ATX supplies are cheap, powerfull and have good protection.

Edited 1 time(s). Last edit at 01/07/2018 02:28PM by newbob.
Re: ESP32 Printer Board
January 07, 2018 02:33PM
Nope. I meant 24V in. the adapter would be for people wanting to run 24V motors. They would have to provide a 24V supply and this board would spit out the correct volts for the various buses.
Re: ESP32 Printer Board
January 07, 2018 05:15PM
Quote
CthulhuLabs
Thought about that too. From the 24 pin ATX connector I route some of the 12V pins to their own 12V bus. That bus is used to power the motors. Have a second 12V bus for things like fans. Then make a 24V adapter board with regulators on it. It would take 24V in and it would have 24V out for the motor bus, 12V out for the fans, 5V out for whatever, and 3.3V for the ICs.

That's certainly a possible solution, but IMO needing a 2-board setup to use 24V power isn't a very attractive proposition. Just about every controller board except Arduino/RAMPS can accept 24V power.


Delta printer calibration calculator, mini IR Z probe, and colour touch screen control panel: [escher3d.com]

Large delta printer, and other 3D printer blog postings: [miscsolutions.wordpress.com]

Disclosure: I have a financial interest in sales of the Panel Due, Mini IR height sensor, and Duet WiFi/Duet Ethernet.
Re: ESP32 Printer Board
January 08, 2018 08:32AM
24pin ATX power supply provides 3.3V, 5V and 12V. 200W, plenty for three extruder heaters and CPU costs $25 (you can get higher wattage PSU when on sale). Seems like a good deal, safer and more efficient than cheap 12V power supplies from ebay. Some ATX PSUs are also dual rail which would separate steppers from uC.

As to stepper motors, how about a power rail with four molex 4 pin sockets for motors? Use 12V directly from ATX PSU or plug in your own through molex or some other higher power single connector if you want to be fancy. 24V solution would require two psu's however that way you don't have to worry about back EMF at all.
Re: ESP32 Printer Board
January 08, 2018 09:27AM
Not a bad idea newbob.

My thoughts on this were this:

Pros:
  1. Easy for newbies to setup
  2. Easily sourced (available at most big box electronics store)
  3. Easy to find a name brand supply
  4. Power circuit needs very basic filtering if that
  5. Other boards do use this solution (look at generation7 boards)

Cons:
  1. Less flexible on motor power
  2. Multiple 12V rails can split supply power so extra sockets needed

What I was thinking was having two 6pin connectors used on graphics cards on the board. That way multiple 12V rails can be plugged into the motor bus.
Re: ESP32 Printer Board
January 08, 2018 10:33AM
I agree with all that. ATX supplies are safer option (if they conform to ATX specifications) and pluggable.

2.5A per motor *5 steppers *12V = 150W.

6pin+6pin = 150W

EDIT: I think it would make sense to leave space on the board for screw down connectors to make it more universal. Even more universal: 6pin+8pin (can be used with 6pin) + screw down.

Edited 2 time(s). Last edit at 01/08/2018 10:40AM by newbob.
Re: ESP32 Printer Board
January 08, 2018 11:12AM
Well the TMC2130s are 1.4A max. I also need power for the heaters.
Re: ESP32 Printer Board
January 08, 2018 11:43AM
ATX power supplies have limits for the Amps per line. And they usually have a lot of Amps on the 5V rail.

Multiplying the voltage of the rail with the max amps on the rails gives the max power on the rail. Adding all rail powers up gives the Watt rating that they sell for.

So if you need 200 W on 12V then a 200W ATX Power supply will not be enough.

24V is also beneficial for bed heating as you don't need too much amps and can therefore make the wires thinner. They will then still be the thickest wires, but you will be able to bend them easier.
Re: ESP32 Printer Board
January 08, 2018 11:50AM
I figure that 3.3V (uC), 5V (fan) and 12V (fan+extruder heaters) would come from 24pin adapter and 6pin+6pin 12V for the motors.

Now, bed heater is a bit tricky since some printers do not use one, some use 12V others 24V or mains.

200W ATX PSU could power everything, except bed heater. ATX specifications require max 20A per 12V rail, ATX 24pin connector provides up to 144W via 12V - good for block heaters and fans but not bed heater.

I think power for the bed heater would need it's own power, just like the steppers, with it's own set of connectors. That way one can plug in 12V from larger ATX PSU, second 24V PSU for bed and steppers or mains through SSR/relay.

EDIT: if going with large ATX PSU, one would need to dedicate one or two 12V rails for the bed heater. At 54W (I think) per sata connector - that's a lot of SATA sockets, probably better to cut the connectors off and use screw terminal - no longer 'beginner friendly'.

Edited 4 time(s). Last edit at 01/08/2018 12:07PM by newbob.
Re: ESP32 Printer Board
January 08, 2018 12:07PM
When my 200W 12V Chinese power supply went out a month ago, I powered my printer from an ATX and it worked quite nicely. My model had about 12A on the 12V line.
The one thing to watch out for is that they won't be able to power a heated bed (unless it's a prety small one). (or unless you could come up with a 5V or 3.3V bed).
The other thing is that the 20 pin connector version does not bring out a lot of 12V wires. (just one) There is a 4-pin connector that has another 2 12V and 2 grounds on it.
Re: ESP32 Printer Board
January 08, 2018 12:17PM
Aparently 20A per rail specification is not per rail but rather per 12V line (each line is supposed to be current limited).

Here's 600W Thermaltake ATX 2.3, single rail 42A 12V available for $44 shipped. Now the only thing to consider would be: how to bring all that power to the bed heater (see below)


@nathan25 ATX 2.0 specification added more 12V power and reduced 5V and 3.3V (and introduced 24 pin connector). I think, although possible to accommodate, we should rather design with consideration for ATX 2.0 and up PSU.

EDIT: considering the $44 Thermaltake mentioned above:

8pin+6pin for steppers
4pin + 4pin for bed (192W+192W)
24pin for everything else

Here's another ATX PSU that would work in above scenario, and is only $30.

Edited 4 time(s). Last edit at 01/08/2018 12:59PM by newbob.
Re: ESP32 Printer Board
January 08, 2018 01:21PM
Like I said the TTMC2130's can handle at most 1.4A for a total of 84W. The official PCIe spec says that the 6pin connectors should handle 75W minimum. The connectors and wires that are used are rate for 8A+ at 12V that is 288W. So unless someone buys the worlds cheapest powersupply a single one is more than enough. I have two.

I added a 8 Pin EPS socket for the heaters. This cable is rated for up to 336W.
Re: ESP32 Printer Board
January 08, 2018 01:28PM
I would like to go with a single 8pin PCIe header for the steppers as that is rated for 150W but I cannot find the part number. Like seriously been googling for over an hour. I can find the part for the 4+4, but they are keyed differently.
Re: ESP32 Printer Board
January 09, 2018 07:49AM
8pin connector
molex 0430450812 [www.digikey.com]


cheap mosfet
DMG9926USD-13 [www.digikey.com]

Edited 1 time(s). Last edit at 01/09/2018 07:54AM by newbob.
Re: ESP32 Printer Board
January 09, 2018 08:51AM
Wrong connector. As far as I can tell it is not made by molex.
Re: ESP32 Printer Board
January 09, 2018 09:41AM
You're right - it has to be 4.2 pitch, like mini fit jr molex connectors. I searched I don't think it is available to mere mortals. Lets just use 6 pins.

Edited 2 time(s). Last edit at 01/09/2018 09:44AM by newbob.
Re: ESP32 Printer Board
January 09, 2018 09:49AM
Nope. That wont work either. The 8pin PCIe connector is keyed weird. Two of the pins have a bridge between them in the plastic housing. Take a look:


Re: ESP32 Printer Board
January 09, 2018 09:51AM
I can find the specs on the connector, just cannot find a manufacturer of the part.
Re: ESP32 Printer Board
January 09, 2018 10:08AM
It seems the connector is manufactured under licence and not available to public. Realistically 8-pin only adds one more ground, compared to 6-pin connector and 6+2 connectors use jumpers for +2 therefore 6 is right gauge to provide extra power.

Edited 1 time(s). Last edit at 01/09/2018 10:18AM by newbob.
Re: ESP32 Printer Board
January 09, 2018 11:05AM
While I agree that a single 6pin should be more than enough, I dont want to risk someone using a cheap power supply and having issues. Just going to stick with the two for now.
Re: ESP32 Printer Board
January 09, 2018 12:08PM
Are you planning on having also screw-down connectors to attach 24V power from secondary PSU or just 'molex' headers?

Edited 1 time(s). Last edit at 01/09/2018 12:51PM by newbob.
Re: ESP32 Printer Board
January 09, 2018 03:20PM
Was planning on just Molex. Trying to idiot proof this thing. Dont want someone attaching 24V and the 4+4 pin at the same time and frying something. Knowing me, I would be that idiot.
Re: ESP32 Printer Board
January 09, 2018 03:43PM
Normally, 24V PSU will not come with 6pin PCIe or 8pin EPS plug, however, maybe you're right - probably safer to require plugs as screw down connectors, that fit on a PCB, are rather flimsy.
Re: ESP32 Printer Board
January 09, 2018 04:26PM
It is not just that. I feel that is someone is trying to move to 24V they should be more than capable of splicing connectors onto their 24V power supply. If they are unable to do that they are very likely to mess something else up like using a 12V heater with 24Vs.
Re: ESP32 Printer Board
January 09, 2018 04:54PM
So wich chip you are going to use ?

i would prefer something integrated , like SAME5x
Mouser

Cool thing is also PoE .. So you can Power the electronics and power on any Power Supply (also 24 and 48 Volt) (ok, also with an USB PowerSupply, but i prefer PoE)

The Price Tag is also nice , One Unit is only 6€ , but everything is on Chip, no need to develop so much auxilary. Maybe it is worth looking at such an intrgrated chip with so much power (for Delta/Scara).

or the ARM ® 32-bit Cortex ®-M4 CPU 168 MHz :
Breadboard Ali Express



greetings

Markus

Edited 3 time(s). Last edit at 01/09/2018 05:17PM by Giftyakapatch.
Re: ESP32 Printer Board
January 09, 2018 05:37PM
I saw someone using P-MOSFETS as low-loss reverse polarity protection circuits. [youtu.be]

You may be able to use some to protect against 24/12V mismatch.

Granted you will have to find MOSFETS large enough to stand the full current of the printer...

Edited 1 time(s). Last edit at 01/09/2018 05:40PM by lhartmann.
Re: ESP32 Printer Board
January 09, 2018 06:32PM
The thing about using a SAMD5X is that it doesn't have WiFi, so we would have to add an esp8266 or 32 anyways.
Also, the esp32 has an Ethernet MAC:
[hackaday.com]

PoE, as far as I am aware, would require external circuitry on both chips. (buck converter)
However, PoE will not be able to power the steppers (forget the bed), so you still need a power supply, and at that point, regulating the 12-24V DC is easier than PoE. (Wikipedia says max ~13 Watts)

It would be nice if we could use one chip instead of 2, but I'm not aware of an ARM chip out there with a good development base that has WiFi and enough pins.
Re: ESP32 Printer Board
January 09, 2018 08:18PM
Quote
nathan25
It would be nice if we could use one chip instead of 2, but I'm not aware of an ARM chip out there with a good development base that has WiFi and enough pins.

Texas Instruments CC3200?
Re: ESP32 Printer Board
January 09, 2018 08:57PM
Good find!
However, correct me if i'm wrong, but I don't see any USB.
Also, the pin count is a little low. Best case, you'd need an external GPIO expander, and a USB-Serial converter.
The only real advantage this one has over the esp32 is the reliable ADC. And the clock is a good deal slower.
Re: ESP32 Printer Board
January 09, 2018 09:03PM
This board will have 2 MCUs. The first is the ESP32. It will be running RepRapFirmware. Its will directly control the stepper drivers as well as handle the WiFi / Bluetooth / SDcard. The second is the SAMD21. It will be running a custom firmware and basically be acting as an advanced I/O expander. It will control the Heaters, Fans, PS_ON, Endstops, as well as the USB interface. The two MCUs will communicate over SPI and three interrupt pins. Both MCUs will have the ability to disable the heaters if a fault is detected.
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