Native Wi-Fi support

This is what sets the MRR ESPA apart from other 3D printer control boards currently available. Based on the ESP32 microcontroller, the MRR ESPA supports 802.11 b/g/n protocols, and a custom fork of Marlin firmware can be used on the board to allow the board to be controlled via a web browser.

This removes the need for the traditional LCD controllers that most other boards use. There is also no need to connect a Raspberry Pi in order to control the printer via a web interface. The web interface is the popular ESP3D webUI, which runs natively on the custom Marlin fork. The printer can then be controlled via any web browser, be it a PC, smart phone, or tablet.

For example, you can slice your 3D model using a slicing software on your PC, then use your PC's web browser to connect to the printer, send the sliced GCODE file to the printer via Wi-Fi. Then, using the same web browser, you can tell the printer to start printing away.

Easily configure Trinamic stepper drivers for SPI mode

Trinamic stepper drivers such as the TMC2130 can be easily used in SPI mode just by setting some jumpers and using a jumper wire. For each stepper driver, there are a set of jumpers. These can be used to set microstepping for stepper drivers such as the A4988 and DRV8825. Or they can be used to configure for SPI mode when using Trinamic stepper drivers such as the TMC2130.

Once the jumpers have been set, a single jumper wire for each Trinamic stepper driver is then used to connect the respective CS pin (also broken out on the MRR ESPA) to the native ESP32 pin to be used.

Higher voltage for probes

One common problem when using inductive or capactive probes is the voltage which they are powered at. These probes are usually connected to the Z endstop, which is powered directly by the microcontroller. This means 5V or 3.3V, but these probes are not designed for such low voltages. Instead, they are usually designed for operation at 6V or more. Using a lower voltage to operate such probes reduces their detection distance, and therefore their effectiveness.

The MRR ESPA has a dedicated connector for such a Z probe which uses the voltage of the power supply to power the probe. If you are using 12V for the power supply, the probe will be running on 12V, and vice versa for when using a 24V power supply. This allows the probe to operate within its specifications, delivering optimal detection distances.

Better heated bed control

The heated bed is electrically isolated from the rest of the electronics on the board via an optocoupler. This means you can easily use one power supply to power the electronics and motors, and a separate power supply (even running at a different voltage) to power the heated bed.

The advantage, of course, is that you can use cheap 12V power supplies for the electronics, motors, fans, and hot end. Then, a separate 24V power supply and 24V heated bed can be used to achieve faster heat-up times.

The board has also been designed for better cooling of the MOSFETs, which can get extremely hot when used with 12V power supplies (which draw double the current, when compared to 24V, for the same power). In the past, an external MOSFET is usually used to power the heated bed because the onboard MOSFET usually gets too hot and becomes a potential fire hazard. With a better MOSFET, the ability to use a higher gate voltage, and better heat dissipation, the MRR ESPA removes the need for external heated bed MOSFETs.

When the bed is powered by 12V, the gate voltage uses 12V directly to achieve a low Rds(on). When the bed is powered by 24V, a voltage divider is used to step down the gate voltage to 12V as the maximum gate voltage is 20V.

Note: While heat dissipation has been improved, it is still recommended to actively cool the board when using 12V for the heated bed. Take note that the heated bed does not draw more than 15A of current.

Firmware

Currently, Marlin 2.0 runs on the MRR ESPA, but to take full advantage of the Wi-Fi features, you will need to use a custom fork of Marlin 2.0 that was developed by luc-github, which allows Marlin 2.0 to also act as a webserver to serve the ESP3D webUI (also written by luc-github) over a web browser. A copy of this fork can be found here. All these software are made available under GPL 3.0.

Special note for the pre-launch version: The pre-launch version comes flashed with the custom fork of Marlin 2.0 as well as the web interface. To modify it, first configure the board the connect to your router. You can do this by:

1. Turn on power to the MRR ESPA, and then connect your PC, smart phone, or tablet to the SSID "MARLIN_ESP" (default password is "12345678").

2. Once connected, open a web browser, and go to "http://192.168.0.1/" which will load the ESP3D web interface.

3. Go to the "ESP3D" tab, and enter your WiFi settings (SSID and password).

4. Reset the MRR ESPA. It should now connect to your router.

5. Use your web browser and go to "http://marlinesp.local/" to access the web interface.

6. You can now update the firmware. Download the custom fork from here, edit Configuration.h and Configuration_adv.h to suit your needs, then compile. If using Arduino IDE, the board should show up as an OTA option under Ports. If using PlatformIO, you can add "upload_port = marlinesp.local" to your platformio.ini file to allow OTA updates. Or, after the firmware has been compiled, use the web interface, go to "ESP3D" tab, and there is an option for firmware update that allows up to upload the firmware.bin file.

7. For more information on firmware, see the GitHub repository and the manual there.

Marlin features that have been tested:

• 3D printing

• SD card operation

• Trinamic stepper drivers in SPI mode

• EEPROM (emulated)

• Wi-Fi

• Babystepping

• Linear advance

• Manual mesh bed leveling

Unsupported features:

• LCD controller (not needed; can be controlled via web interface using any web browser)

• Trinamic steppers in UART mode (unsupported due to insufficient pins)

Untested features (supported in theory):

• MAX6675

• Neopixel

• BLTouch

Pricing

We are offering this product at a very affordable price because the aim of this project is not to make profits, but to allow other 3D printer enthusiasts access to a 3D printer control board which has native Wi-Fi support. We believe this board will make it easier for 3D printer enthusiasts to operate their printers.

Therefore, to allow more people access to this board, the board is basically priced to cover its production and shipping costs (including fees paid to PayPal). Making this board available to a wider audience is our way of contributing back to the open source community which has made the development of this board possible.

About this project and us

Work started on this open source project in late 2018. We started by looking at how the ESP32 microcontroller, which comes with Wi-Fi, can be used to control a 3D printer. With contributions from the open source community, we now have a prototype that is almost ready for delivery. Given the mature stage of development, we feel we are now ready to make this board available to other 3D printer enthusiasts who want to operate their 3D printers via Wi-Fi but do not have the means to design their own DIY boards.

This project is based on the great work by a few people in the ESP32 and 3D printing community who worked on implementing ESP32 support in Marlin 2.0 as well as the ESP3D web interface for controlling 3D printers via a web browser. Please see the attribution on our GitHub page for details. Please note that these developments are open source projects released under various open source licenses.

This project is licensed under CERN Open Hardware Licence v1.2.

Notes

• This product will be provided as-is. Basic documentation will be made available via our GitHub page. It is meant for 3D printer enthusiasts with a moderate level of experience and skill; you will need to know how to wire up a 3D printer as well as flash Marlin firmware.

• Users are expected to understand the inherent risks in 3D printing, which includes the probability of fires due to the high temperatures involved. While we have gone through the due diligence of testing the product, users use this product at their own risk, and we will not be liable for any death, injury, or damage that arise from the use of this product.

• Additional safety-related notes can be found on our GitHub page.

• The board uses the FCC-approved ESP32-WROOM-32 or ESP32-S for WiFi.

For more information, please see our GitHub page:

https://github.com/maplerainresearch/MRR_ESPA