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* Oled2 (#834)



* Update platformio.ini


* Cleanup

* Update platformio.ini

* Turn off soft limits with max travel (#836)


* Yalang YL620 VFD (#838)

* New SpindleType YL620

Files for new SpindleType Yalang 620. So far the contents are a duplicate of H2ASpindle.h and H2ASpindle.cpp

* Added register documentation and implemented read and write data packets

* Some fixes, mostly regarding RX packet length

* OLED and Other Updates (#844)

* publish

* Updates - CoreXY and OLED

- Moved position calculation out of report_realtime_status(...) so other functions can access it.
- Added a function to check if a limit switch is defined
- CoreXY fixed bug in forward kinematics when midtbot is used.
- Modified OLED display.

* Cleanup for PR

* Delete midtbot_x2.h

* Incorporated PR 846

- Some OLED cleanup
- verified correct forward kinematics on MidTbot

* Pio down rev (#850)

* Update platformio.ini

* Update Grbl.h

* Use local UART driver not HardwareSerial (#857)

* Use local UART driver not HardwareSerial

The HardwareSerial driver is broken in Arduino framework versions
1.0.5 and 1.0.6 .  espressif/arduino-esp32#5005
Instead of waiting for a fix, I wrote a very simple UART driver that
does exactly what we need with no unnecessary bells and whistles to
cause problems.

* Added missing files, changed method signatures

The methods implemented by the UART class now
have the same signatures as the HardwareSerial
class, so it will be easy to switch back if we
need to.

* Incorporated suggestions from Stefan

* Fixed TX_IDLE_NUM bug reported by mstrens

* Quick test for Bf: problem

This is not the final solution.

* Fixed stupid typo in last commit

* Another test - check for client_buffer space

* Use the esp-idf uart driver

You can revert to the direct driver for testing by
defining DIRECT_UART

* Uart class now supports VFD and TMC

* data bits, stop bits, parity as enum classes

The constants for data bits, stop bits, and parity
were changed to enum classes so the compiler can
check for argument order mismatches.

* Set half duplex after uart init

* Init TMC UART only once

* rx/tx pin order mixup, missing _uart_started

* Test: use Arduino Serial

This reverts to the Arduino serial driver for
UI communication, leaving the VFS comms on the
Uart class on top of the esp_idf UART driver.

You can switch back and forth with the
line in Serial.cpp


* Added debug messages

* Update Grbl.h

* Update platformio.ini

Co-authored-by: bdring <>

* Fixed spindle sync for all VFD spindles (#868)

* Implemented H2A spindle sync fix. Untested.

* Changed the spindle sync fix to be in the VFD code.

* Update Grbl.h

Co-authored-by: Stefan de Bruijn <>
Co-authored-by: bdring <>

* New jog fix (#872)

* Applied 741 to new Devt

* Make kinematics routines weak

to eliminate ifdefs

* Fixed warning

* Update build date

Co-authored-by: bdring <>

* Big kinematics cleanup (#875)

* Applied 741 to new Devt

* Make kinematics routines weak

to eliminate ifdefs

* Fixed warning

* Big kinematics cleanup

* Cleanup

* no isCancelled arg for jog_execute; return it instead


* Made OLED compliant with new kinematics

* Added system_get_mpos

* system_get_mpos() returns float*


* Cleanup after testing

- Had MPos and WPos text on OLED backwards.
- Added my cartesian test def
- Will remove test defs before merging to devt.

* Cleanup of remaining user optional code.

* Fixed delta kinematics loop ending early.

* Account for jog cancel in saved motor positions

* Update Grbl.h

Co-authored-by: bdring <>

Co-authored-by: Mitch Bradley <>
Co-authored-by: marcosprojects <>
Co-authored-by: Stefan de Bruijn <>
Co-authored-by: Stefan de Bruijn <>

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Grbl (CNC Controller) For ESP32

Project Overview

Grbl_ESP32 started as a port of Grbl to the ESP32. The power of the ESP32 has allowed this firmware to grow far beyond the limitations of 8-bit AVR controllers. Here are some of the current features

  • Motors

    • Control up to 6 coordinated axes (XYZABC)
    • Each axis can have 1 or 2 motors each for a total of 12 motors
    • Dual motors axes can optionally auto square using a home switch and independent control for each motor.
    • Motor drivers can be dynamically assigned to axes, so a 4 motor XYZA controller could be converted to a XYYZ (dual motor Y axis) without any hardware changes.
    • Step rates up to 120,000 per/second.
    • Trinamic (SPI controlled) stepper motors are supported including StealthChop, CoolStep and StallGuard modes. Sensorless homing can be used.
    • Unipolar stepper motor can be directly driven
    • RC hobby servos can be used as coordinated motors with acceleration and speed control.
  • Peripherals

    • Limit/Homing Switches with debouncing
    • User input buttons (hold, resume, reset)
    • Coolant control (Mist, Flood)
    • Z Probe (any axis)
    • Safety Door (open door safely retracts and stops spindle, can be resumed)
    • Additional I/O via shift register and I/O expanders supported (on dev branches)
  • Job Control

    • Instant feed hold and resume
    • Feed rate override
    • Spindle speed override
  • Spindles

    • PWM
    • RS485 Modus
    • DAC (analog voltage) 0-10V
    • Relay Based
    • RC type Brushless DC motors using low cost BESCs
    • Laser PWM with power/speed compensation
    • Easy to create custom spindles
  • Connectivity

    • USB/Serial
    • Bluetooth/Serial Creates a virtual serial port on your phone or PC. Standard serial port applications can use Bluetooth.
    • WIFI
      • Creates its own access point or connects to yours.
      • Built in web server. The server has full featured CNC control app that will run on your phone or PC in a browser. No app required.
      • Telnet sending of gcode
      • Push notifications (like...job done, get a text/email)
      • OTA (over the air) firmware upgrades.
  • SD card. Gcode can be loaded and run via WIFI.

  • Compatibility

    • Grbl_ESP32 is fully backward compatible with Grbl and can use all gcode senders.
  • Customizable

    • Easy to map pins to any functions.
    • Custom machines can be designed without touching the main code.
    • Custom initialization
      • Kinematics
      • Custom homing
      • Tool changer sequences
      • Button macros (run gcode sequence, etc.)
      • Custom end of Job sequence
      • RTOS Real time operating system allows background monitoring and control without affecting motion control performance
  • Fast boot

    • It boots in about 2 seconds (unlike Raspberry Pi, Beagle Bone). Does not need to be formally shut down. Just kill the power

Test Drive It

Grbl_ESP32 has a test drive mode. If you just compile it and load it onto an ESP32, it will create a virtual machine without any pins mapped. This allows you to safely test drive it without any attached hardware. Everything is functional including the WIFI and web user interface. Things like homing, that require feedback from actual switches cannot be done.

Using It

Important compiling instructions are in the wiki

The code should be compiled using the latest Arduino IDE. Follow instructions here on how to setup ESP32 in the IDE. The choice was made to use the Arduino IDE over the ESP-IDF to make the code a little more accessible to novices trying to compile the code.

I use the ESP32 Dev Module version of the ESP32. I suggest starting with that if you don't have hardware yet.

For basic instructions on using Grbl use the gnea/grbl wiki. That is the Arduino version of Grbl, so keep that in mind regarding hardware setup. If you have questions ask via the GitHub issue system for this project.


The roadmap is now on the wiki.


The original Grbl is an awesome project by Sungeon (Sonny) Jeon. I have known him for many years and he is always very helpful. I have used Grbl on many projects. I only ported because of the limitation of the processors it was designed for. The core engine design is virtually unchanged.

The Wifi and WebUI is based on this project.


There is a Discord server for the development this project. Ask for an invite


Start asking questions...I'll put the frequent ones here.


This project requires a lot of work and often expensive items for testing. Please consider a safe, secure and highly appreciated donation via the PayPal link below or via the Github sponsor link at the top of the page.