Welcome! Log In Create A New Profile

Advanced

ESP32 Printer Board

Posted by CthulhuLabs 
Re: ESP32 Printer Board
January 16, 2018 09:32PM
Hmm I think the SAMD21 has oscillator outputs.
Re: ESP32 Printer Board
January 17, 2018 06:33AM
- Pull Up Resistors added to the SD card
- Diodes added to the stepper drivers
- Series resistors added to the ADC
Re: ESP32 Printer Board
January 17, 2018 10:38AM
From my research an external clock for the TMC2130s is not necessary in this application.
Re: ESP32 Printer Board
January 18, 2018 07:28AM
8 pin pcie header from aliexpress.
Re: ESP32 Printer Board
January 18, 2018 08:23AM
Nice find. Wonder if the manufacturer will admit to making that part.
Re: ESP32 Printer Board
January 24, 2018 02:42PM
Starting to layout the board. Have a crap ton more components to put down and arrange plus the traces to layout.

It would be a great help if more people could review the schematic I posted in this thread on the 16th of January (second to last post on page 8 of this thread). I am still not convinced I have everything right.
Attachments:
open | download - layout.png (305.8 KB)
Re: ESP32 Printer Board
January 25, 2018 05:39AM
How many layers do you think you'll need? When I tried to layout 2 layer board I quickly realized that TMC2130 package is designed for 4 layers minimum and high speed SPI signals complicate the layout further..
Re: ESP32 Printer Board
January 25, 2018 07:37AM
I was hoping to have no more than 6 layers.
Re: ESP32 Printer Board
January 30, 2018 11:41AM
Hmm trying to figure out a good way to handle the fan tach pins. The tach output from a fan is at whatever voltage the fan is being run on. As such I need a circuit that can take in potentially anything from 12V all the way to 24V (or higher) and output 3.3V.
Re: ESP32 Printer Board
January 30, 2018 11:46AM
The tacho output from a fan is normally open-drain or open-collector. The main problem is that it is unreliable if you are applying PWM to the fan power supply, especially if you are switching the negative terminal of the fan. In RRF we support the tacho output only when the fan is a 4-wire type with a separate PWM control input.


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 [www.duet3d.com].
Re: ESP32 Printer Board
January 30, 2018 12:09PM
Interesting. The Einsy Rambo seems to be switching the negative pin and is reading the tach. Circuit is on page 6 of this doc:

[github.com]
Re: ESP32 Printer Board
January 30, 2018 02:09PM
Reading the tach on a 3-wire fan will work when the fan is full on, without PWM. This would be the case typically for a hot end heatsink fan. If you try to read it when PWM is being applied via the negative fan power wire, the tach reading will be unreliable.

Edited 2 time(s). Last edit at 01/30/2018 02:11PM by dc42.

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 [www.duet3d.com].
Re: ESP32 Printer Board
January 30, 2018 02:39PM
I did a little searching, and it looks like the common option when PWMing 3 wire fans is to stop PWMing as you read the tach. If it's short enough, it won't affect the speed, but will give you an accurate speed reading.
source: [www.pcbheaven.com]
Re: ESP32 Printer Board
January 31, 2018 06:37AM
I would guess that this technique works well with larger fans - with high inertia - but would be inaccurate with small fans.

EDIT: On the other hand small fans spin fast, therefore pulse time is shorter and if one limited sample time to one pulse it may work reasonably well.

Edited 1 time(s). Last edit at 01/31/2018 06:42AM by newbob.
Re: ESP32 Printer Board
January 31, 2018 07:26AM
Not sure about that actually. Smaller fans tend to be higher rpm. As such the length of time you need to set the PWM to 100% is shorter to get that one full pulse from the tach. Also at higher speeds the air resistance increases which would compensate for the lack of inertia. Lastly as long as you are doing it at a constant interval and as part of a feed back loop that quick pulse at 100% would be factored into the fan speed. Yes small fans would be hard to run at super slow speeds, but I do not think anyone expects them to. The big thing though is I would be less concerned about getting accurate readings and more concerned about getting any reading. I don't really care about having precise fan speeds. I care about making sure that the fan is actually spinning and isnt blocked by something.
Re: ESP32 Printer Board
January 31, 2018 12:06PM
You need to read at least 2 adjacent pulses so that you can measure the interval.


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 [www.duet3d.com].
Re: ESP32 Printer Board
February 05, 2018 05:55AM
It apprears that ESP32-WROOM-32U was just released. This version has u.fl antenna connector and no keep out zone so it does not have to 'hug' edges of the PCB like ESP32D does.

Edited 1 time(s). Last edit at 02/05/2018 05:56AM by newbob.
Re: ESP32 Printer Board
February 05, 2018 10:20AM
Interesting. I have seen that floating around. Might offer that as a variant, but for now I am going to stick to the one with a built in antenna.
Re: ESP32 Printer Board
February 14, 2018 07:55AM
Just run some ADC tests and I'm getting .6 precision for 75-300 range and .4degC for 123-300degC

I used 100k (4000 beta) thermistor in a voltage divider so voltage decreased with temperature. ESP32 has three* voltage ranges, 0.1 to VCC, 0.1 to 2.2 and 0.1 to 1.1V for my setup, 75degC was 2.2V so middle ADC range can be used and above 123degC (1.1V) most precise range. At highest resolution ADC step is 0.5mV and 1degC in the 220degC region is 2mV.



* actually there are four ranges but .1 to 1.5V range did not seem like it would be much different from .1 to 2.2V.

Edited 4 time(s). Last edit at 02/14/2018 09:42AM by newbob.
Sorry, only registered users may post in this forum.

Click here to login