Phi Mainboard 5LC

An open source ESP32 3D printer controller with built-in Wi-Fi and Ethernet

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Phi Mainboard 5LC is a 3D-printer controller with a focus on network connectivity. In addition to all the things that other controller boards can do, Phi provides a web interface to configure and control your printer, upload G-code files, and start and monitor your prints. With Phi, you can do away with a separate single-board computer (like a Raspberry Pi) which introduces cost, needs non-trivial setup, and takes forever to start up.

While Phi’s feature set is geared toward 3D printers, it can also be used to drive other digital-fabrication machines, such as CNC machines.

See Phi In Action

Phi is already able to do 3D prints. Here it is fitted on a Prusa i3 MK3S to print a XYZ calibration cube.

Powerful Brains

Yes, plural. Powering Phi are two processors: an ESP32-S3-WROOM-1 module and an SAME51 microcontroller.

The ESP32-S3-WROOM-1 is an Espressif module with a 240 MHz dual core Xtensa microprocessor, 8 MB of flash, 512 K of SRAM, and Wi-Fi and Bluetooth support. This processor handles networking and various interfaces: USB, SD card slots, graphical displays, etc.

The SAME51 is a Microchip microcontroller with a 120 MHz Cortex-M4F, 512 K of flash, and 192 K of SRAM. This processor handles kinematics, stepping, digital and analog I/O, and other realtime control of the machine. On other controller boards, a single processor handles everything.

On Phi, each processor focuses on the tasks for which it is best suited. This delegation of roles ensures that networking and other ‘extras’ do not bog down motion control and other time-sensitive operations.

Fast & Flexible Networking

Phi is ready for your network setup, wired or wireless. You might use your machine on Wi-Fi initially, but should you need to go wired with Ethernet in the future (or vice-versa), Phi has you covered!

You won’t have to wait for your machine, either. Phi boots and connects to your network in seconds, so you can access the web interface and get to printing faster.

Runs RepRapFirmware

Phi runs RepRapFirmware, a firmware that has a huge legacy in the 3D-printing world and that is credited for introducing numerous advancements. It supports most machine kinematics. More importantly, this means there is no need to rebuild when configuring Phi for your machine. Most settings in the firmware, especially those related to kinematics, are configured using G-Code, so you can even make changes on the fly!

Oozing With Features

Aside from its powerful brains and flexible network connectivity, Phi is a fully-featured controller board. It is built on a four-layer, 123 mm x 100 mm board with two-ounce copper outer layers for better heat dissipation of stepper drivers and power MOSFETs. Here’s a tour of the hardware:

click to expand

1. 10/100 Mbps Ethernet
2. Micro-USB port
3. ESP32-S3-WROOM-1 2.4 GHz Wi-Fi + Bluetooth 5 (LE) module
4. Micro-SD slot
5. Processor activity indicator LEDs
6. Reset button
7. SAME51 microcontroller
8. Duet 3 Expansion Mini 2+ *
9. Five built-in TMC2209 stepper drivers
10. One dual-port TMC2209 stepper driver
11. Two extruder heater ports
12. Three high-current power MOSFETs
13. Two fan ports with tach input
14. Two fan ports without tach input
15. Servo/VFD port
16. Always-on output port
17. Heated bed output
18. Power options:

  • On-board or external 12 V select
  • On-board or external 5 V select
  • Fan, always-on output, servo/VFD 12 V or input voltage (VIN) select

19. Bed heater fuse
20. Five on-board voltage regulators:

  • 5 V, 3 A for internal use (5V_CORE)
  • 3.3 V, 1 A for internal use (3.3V_CORE)
  • 5 V, 3 A for external use
  • 3.3 V, 1 A for external use
  • 12 V, 3 A for external use

21. Input voltage (VIN) fuse
22. Input voltage (VIN)
23. PS_ON, external 5 V input
24. External 12 V input
25. CAN-FD port:

  • Duet 3 Expansion 3HC *
  • Duet 3 Toolboard 1LC *
  • Duet 3 Expansion 1XD *

26. Neopixel port
27. Seven general-purpose input/output ports, IO0 – IO6: digital, analog, PWM; inputs are up to 30 V tolerant
28. Three thermistor inputs
29. PT100 temperature sensor daughter board *
30. Thermistor fuse
31. EXP1
32. EXP2
33. 10-pin PanelDue
34. 4-pin PanelDue
35. External Reset
36. Power indicator LEDs

* Phi’s feature set is based on the open-source Duet3D™ Duet 3 Mini 5+, hence the compatibility with Duet3D™ hardware.


Phi Mainboard 5LCDuet 3 Mini 5+SmoothieboardSKR 2
ManufacturerLikha LabsDuet3DSmoothiewareBigTreeTech
NetworkingWi-Fi and EthernetWi-Fi or EthernetEthernet-
ProcessorESP32-S3-WROOM-1-N8 + SAME51N19ASAME54P20ALPC1769FBD100STM32F407VGT6
CoreDual-core Xtensa-LX7 + Cortex-M4FCortex-M4FCortex-M3Cortex-M4F
Frequency240 MHz + 120 MHz120 MHz120 MHz168 MHz
RAM512 KB + 192 KB256 KB64 KB192 KB
Flash8 MB + 512 KB1 MB512 KB1 MB
SD cardSDIO (fast)SDIO (fast)SPI (slow)SDIO (fast)
USB DeviceYesYesYesYes
USB HostNoNoNoYes
Steppers5x TMC2209, 2 A RMS, 1/256 Microstepping, Silent, Sensorless homing support5x TMC2209, 2 A RMS, 1/256 Microstepping, Silent, Sensorless homing support5x A5984, 2 A RMS, 1/32 Microstepping-
12 V regulator3 A1 A--
5 V regulator2x 3 A1 A-4 A
3.3 V regulator2x 1 A2x 0.8 A0.8 A0.8 A
Heater outputs1x Bed, 2x Hotend1x Bed, 2x Hotend2x Bed, 2x Hotend1x Bed, 2x Hotend
Thermistor Inputs3343
NeoPixel PortYesYesNoYes
Servo/Laser/SSR/VFD Port (5 V drive signal)YesYes (signal shared with a fan)NoNo
GPIO (for endstops, filament monitor, z-probe, etc.)1412339
Fans4 PWM (2 with tach input), 1 always-on, VIN/12 V selectable4 PWM (2 with tach input), 1 always-on, VIN/12 V selectable-3 PWM, 2 always-on
Input Voltage (VIN)11 V - 25 V11 V - 25 V12 V - 24 V12 V - 24 V
Displays supported (without need for adapter/significant modification)PanelDue, Mini 12864, RepRapDiscount Full Graphic Smart ControllerPanelDue, Mini 12864-Mini 12864, TFT35, RepRapDiscount Full Graphic Smart Controller
CAN ExpansionsDuet 3 Expansion 3HC, Duet 3 Toolboard 1LC, Duet 3 Expansion 1XDDuet 3 Expansion 3HC, Duet 3 Toolboard 1LC, Duet 3 Expansion 1XD--
Other ExpansionsPT100 temperature sensor daughter board, Duet 3 Expansion Mini 2PT100 temperature sensor daughter board, Duet 3 Expansion Mini 2, SBC-ESP-12S/ESP-07S Wi-Fi Module, EXP-MOT Driver Expansion (shared with display headers)

Open Source

Phi’s schematic, PCB layout, and firmware will be publicly available in our GitHub repository shortly after the product ships. Furthermore, Phi was created using open source and freely-available tools: KiCAD for schematic capture and PCB layout; GCC and CMake for firmware development.

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