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Project Features

Engineering type     motion control

Design style      Exquisite design, taking into account both appearance and performance

Rich practical     interfaces and powerful functions

Application range     : writing machines and laser engraving machines with various types of actuators

Project purpose

Before starting this project, I maintained a Grbl motion controller project based on STM32. In order to add offline functions and networking functions to this controller, I conducted a long period of development, including controller hardware, controller programs, and PC host. Due to the limitations of the technical level of the machine and the mechanical structure used for testing, the use effect of the finished product is unsatisfactory.

"Grbl_Esp32" is a project derived from "Grbl". After coming into contact with this project, I was surprised to find that it has good support for the functions I need. I also realized that it is not advisable to work behind closed doors. Only by participating in open source Only by communicating and learning with others during the project can you better master the knowledge in related fields.

In June 2020, there was no open source hardware compatible with "Grbl_Esp32" in China at this time. I came up with the idea of ​​making an open source "Grbl_Esp32" hardware specialized as a writing machine controller to learn the "Grbl_Esp32" project. idea.

Project structure

Hardware part: XBoard E series writing machine controller uses ESP32 module as the main control; onboard 12V to 5V DC-DC step-down circuit, 5V to 3.3V LDO step-down circuit, USB to TTL communication circuit, automatic download circuit, large Power MOS tubes, etc.; can drive 3-way stepper motors, 9G servos, 2pin lasers, 3pin lasers, electromagnets, etc.; has rich indicator lights; and has relatively good protection for IO.

Software part: "Grbl_Esp32". The open source project "Grbl_Esp32" is the result of the fusion of project "Grbl" and project "ESP3D". While serving as a motion controller, it inherits the good interactive experience of "ESP3D". Compared with the native "Grbl", the biggest feature of "Grbl_Esp32" is that it supports multiple communication methods, such as USB/Serial, Bluetooth/Serial, Telnet, WebSocket, etc., and can use an SD card to run files offline.

my contribution

Designed, produced and open sourced the project "XBoard E Series Writing Machine Controller", wrote a detailed user manual (33 pages with pictures and text), rewritten the "Grbl_Esp32" source code to customize some functions for the controller, such as: setting the model online , electromagnet current strategy, steering gear support, etc.

Project status

After more than half a year of polishing, the project will soon launch official versions, including XBoard E1.0, XBoard ET1.0 and XBoard RE1.0.

There are currently three branches of the project: XBoard E and the yet-to-be-released XBoard ET and XBoard RE.

Among them, XBoard E is the main branch, and XBoard ET and XBoard RE are derived branches.

XBoard E uses direct plug-in drive modules and can support commonly used stepper motor drive modules, such as A4988, TMC2208, TMC2130, etc.

XBoard ET has an onboard TMC2225 stepper motor driver with a higher degree of integration.

XBoard RE has almost the same functions as XBoard E, but its shape is 2*24CM rectangular and can be installed on 2020 aluminum profiles.

Currently the main version: E1.1

Program source code

Original project: https://github.com/bdring/Grbl_Esp32 , more stable

My project: https://github.com/KnightSin/Grbl_Esp32 , more features, modified and updated as needed

PCBA pictures

ET0.3 (Abolition)

E0.4 (under testing)

ET0.4 (under testing)

Wiring diagram

Modify records

(June 30, 2020 13:12) Since the hardware part has added an automatic download circuit - using the two pins RTS and DTR of the serial port chip - the board will always be in the state after connecting Kuixiang Engraving and ChiWriting. In reset state, a lot of garbled characters are printed. We have already communicated with the developers of Kuixiang and Chisu, and certain processing needs to be done at the software level. If you need to use these two software now, you can choose not to solder the two transistors Q1 and Q2 - in this case, it will automatically The download circuit will lose its function. You need to press and hold the BOOT button and then press the RESET button to enter the download mode.

(July 2, 2020, 16:32) A4988 was drawn incorrectly in the schematic diagram - 1A and 1B were in the wrong order - causing the silk screen to be drawn incorrectly as well. This error has been corrected and submitted to the author of the schematic module.

(July 5, 2020 15:53) Adjust the pin sequence of the limit switch interface and the pin sequence of the solenoid interface to be more consistent with customary

(July 6, 2020 18:09) Adjust some wiring to make it more reasonable

(July 6, 2020 19:11) Adjusted the position of the status indicator light and optimized some wiring. In view of the significant changes in the PCB, a minor version number is raised and the version number is changed to E0.2

(July 7, 2020 16:49) IO34/IO35 was incorrectly used as the output pin. It has been corrected and replaced STATUS_LED and STEPPERS_DISABLE_PIN with IO13/IO12.

Input Only (no pullup/pulldown) If you do not have external pull up or pull down resistors. Do not use these pins!

GPIO_NUM_34 GPIO_NUM_35 GPIO_NUM_36 GPIO_NUM_37 GPIO_NUM_38 GPIO_NUM_39

(July 7, 2020 18:03) Corrected the description of the Z axis in the PIN table on the back of the PCB

(July 16, 2020 19:34) The schematic symbol/3D package of LED has been modified to make the color correspond to the actual; the schematic symbol and package of XH2.45 2P have been modified to make it consistent with the package of XH2.54 More unified; adjusted the position of some silk screens; adjusted component numbers

(July 24, 2020 13:35) Added hardware support for the SPI mode of the TMC2130 stepper motor driver module, modified the package of the SD card slot, modified the package of the chip electrolytic capacitor, and optimized some wiring . In view of the significant changes in the PCB, a minor version number was raised and the version number was changed to E0.3.

(August 4, 2020 04:09) Added a branch ET0.3 to integrate 3-way TMC2225 stepper motor driver

(August 6, 2020 10:05) On the basis of E0.3, a self-restoring fuse is added to the USB power supply part, and a current-limiting resistor is added to some output IOs to prevent the reverse-plug driver from burning out the ESP32 module. In view of the significant changes in the PCB, a minor version number was raised and the version number was changed to E0.4.

(21:44 on September 4, 2020) Corrected the ESP32 package, changed the 0603 resistor, capacitor and LED package; added a TVS SMAJ5.0A; greatly adjusted the wiring; added on the basis of E0.4 A branch, ET0.4, integrates 3-channel TMC2225 stepper motor driver; branch ET0.3 is abolished; the servo power supply method is changed, USB can no longer power the servo, and the servo must be connected to a DC 12V power supply before the servo can work; changed The control logic of the electromagnet. When the control pin is in a high-impedance state, the electromagnet no longer attracts; some of the silk screen printing has been changed.

//(23:30 on September 27, 2020) Changed the subdivision pin layout scheme to make it closer to usage habits; changed the use of daisy chain to connect all motor drives in the original SPI mode to one chip for each axis drive Select, IO0 and IO2 are used for this purpose; upgrade a minor version number, and the version number is changed to E0.5

//(October 9, 2020, 18:20) Adjust some silk screens, change the USB input power pin silk screen from P5V to U5V, and adjust the description of TMC_CS# from 22 to IO22/IO0/IO2

//(12:40 on December 28, 2020) SD_CD/limit switch pins are moved to read-only pins; in the new version, the extra 3 IOs, 2 power pins and reset pins are lead out , can be connected to a button module or serial port screen, etc.; changed the SPI mode from daisy chain to one chip select for each driver (one TX for each driver in UART mode); tested using the BOOT button as a function button, which is equivalent to adding A user-programmable button

In addition, in the new version, the SPI mode is changed from daisy chain to one chip select for each driver (one TX for each driver in UART mode). The BOOT button is tested as a function button, which is equivalent to adding a button that can be programmed by the user.

(11:33 on June 5, 2021) Replace PC817 with 2 high-speed optocouplers. The extra 1 is used to convert the level of the spindle PWM signal from 3.3V to 5.0V (note that the logic is reversed) ;Upgrade the project version number to E1.1

Project derivation

1. 3D printing “steel mesh” tutorial

https://www.bilibili.com/read/cv6741734

2. Create 3D models and render them for LCEDA projects

https://www.bilibili.com/read/cv6758801

User manual (new version is being prepared, so stay tuned)