Control Panel for K40 laser cutters/engravers

What it CAN do:

• Monitor input/output coolant flow and temperature (using "YF-B4"-type sensors and thermistors)
• Monitor lids opening state (using two microswitches)
• Monitor for fire (using an LM393 IR flame sensor module)
• Control the CO2 laser interlock based on the current state
• Control a 5V/12V alarm indicator
• Control 5V/12V lights
• Control 5V/12V laser diodes
• Control a motorized bed (based on this design, but it should work with other ones as long as the stepper can be controled using a DRV8825 driver)
• Retrieve the current state of the machine and move the laser head through UART (requires a FluidNC board)
• Enable/disable air assist (requires a FluidNC board)
• Expose sensors/state data through an API

What it CANNOT do (yet):

• Start or control a job
• Trigger the laser
• Send arbitrary Gcode

For the control panel:

• 1x 38 pins ESP32-S with a spacing of 24mm between pin rows (not 25.5mm)
• 1x ST7796 (recommended) or ILI9488 (slower) 3.95" LCD screen
• 1x DRV8825 stepper driver
• 1x TSR-1-2450 5V regulator (or a less-efficient L7805CV - you will want to add a heatsink if you go this way)
• 4x IRLML6244 N-channel MOSFETs
• 1x MF-LSMF200/24X-2 resettable fuse
• 4x 1N4007 diodes
• 1x 15kΩ 1/4W R1206 SMD resistor
• 3x 2.2kΩ 1/4W R1206 SMD resistor
• 9x 10kΩ 1/4W R1206 SMD resistors
• 3x 1kΩ 1/4W R1206 SMD resistors
• 4x 220Ω 1/4W R1206 SMD resistors
• 1x 0.1uF electrolytic capacitors
• 1x 100uF electrolytic capacitors
• 1x 0.33uF ceramic capacitors
• 4x 0.1uF ceramic capacitors
• 4x 2.2-3V 0805 SMD LEDs
• 1x SRD-12VDC-SL-C relay
• 1x 2P PCB terminal blocks (5mm pitch)
• some 2.54mm pin headers / XH connectors / jumpers

Other things you may need:

• 1x FluidNC controller board
• 1x motorized bed with a NEMA17 stepper and a limit switch
• 1x air compressor for air assist
• 2x YF-B4 flow sensor with a thermistor (preferably one with a 50kΩ resistance at 25°C and B=3950K)
• 1x LM393 IR flame sensor module
• 2x micro switches (1 for each lid you want to monitor, you can use a jumper instead if desired)
• 1x (or 2x depending on your needs) 5V/12V laser diodes
• 1x 5V/12V LED light (for the enclosure)
• 1x 5V/12V alarm module (for instance a blinking light)

Make sure you have Python 3.x installed on your system, then run:

# Install/update Platform.io
pip install --upgrade platformio

# Build the firmware (default LCD driver: ST7796)
pio build

Then flash your ESP32 using the upload target.

OTA updates are available using the OTA target. In order to use it copy the .env.dist file to .env and change the values of OTA_UPLOAD_URL, OTA_LOGIN and OTA_PASSWORD in it accordingly to the settings of your control panel.

You can also take a .bin file and upload it through the ElegantOTA interface available at http://<YOUR_PANEL_IP>/update.

Production files can be found in the gerber folder of this repository.

This PCB requires some SMD soldering, this is not that hard to do but I would still recommend practicing a bit before trying to build that board.

Some notes:

• If you are using a different PSU for the control panel and your FluidNC board make sure that both of them have a common ground in order for UART to work as intended
• Some MS1/MS2/MS3 jumpers have to be installed if you want to use microstepping, refer to the DRV8825 datasheet to know which ones
• Also use jumpers to select the voltage for "Diodes" and "Lights" connectors
• Use shielded cables if needed (and ground the shield on one side only)

GET http://<YOUR_PANEL_IP>/api/info

{
    "firmware": {
        "version": "9da28a82",
        "build_date": "Apr 30 2023 18:31:43"
    },
    "system": {
        "chip": {
            "model": "ESP32-D0WDQ5",
            "revision": 1
        },
        "heap": {
            "free": 80268,
            "total": 257148
        },
        "cpu": {
            "freq_mhz": 240,
            "load_percent": {
                "core_0": 0,
                "core_1": 0.100000001
            }
        },
        "tasks": {
            "display_update": {
                "state": "ready",
                "priority": 1,
                "high_water_mark": 1348
            },
            "bed_update": {
                "state": "blocked",
                "priority": 0,
                "high_water_mark": 1044
            },
            "state_update": {
                "state": "ready",
                "priority": 0,
                "high_water_mark": 600
            },
            "grbl_rx": {
                "state": "blocked",
                "priority": 1,
                "high_water_mark": 1508
            },
            "grbl_tx": {
                "state": "blocked",
                "priority": 1,
                "high_water_mark": 1992
            },
            "settings_save": {
                "state": "blocked",
                "priority": 0,
                "high_water_mark": 472
            },
            "cpu_monitor": {
                "state": "blocked",
                "priority": 0,
                "high_water_mark": 340
            },
            "async_tcp": {
                "state": "running",
                "priority": 3,
                "high_water_mark": 15064
            }
        }
    }
}

GET http://<YOUR_PANEL_IP>/api/sensors

{
    "sensors": {
        "cooling": {
            "flow": {
                "input": 5.619999886,
                "output": 5.60124556
            },
            "temp": {
                "input": 18.89999962,
                "output": 21.3
            }
        },
        "lids": {
            "front": "opened",
            "back": "closed"
        },
        "flame_sensor": {
            "triggered": false
        }
    }
}

GET http://<YOUR_PANEL_IP>/api/alerts

{
    "alerts": {
        "cooling": false,
        "lids": true,
        "flame_sensor": false
    }
}

GET http://<YOUR_PANEL_IP>/api/relays

{
    "relays": {
        "interlock": false,
        "cooling": true,
        "alarm": false,
        "lights": true,
        "beam_preview": true
    }
}

GET http://<YOUR_PANEL_IP>/api/grbl

{
    "state": 1,
    "w_pos": {
        "x": 0,
        "y": 0,
        "z": 0
    },
    "m_pos": {
        "x": 0,
        "y": 0,
        "z": 0
    },
    "wco": {
        "x": 0,
        "y": 0,
        "z": 0
    },
    "buffer": {
        "planned_buffer_available_blocks": 100,
        "rx_buffer_available_bytes": 20
    },
    "feed": {
        "rate": 0,
        "spindle_speed": 0
    },
    "line_number": 0,
    "active_pins": {
        "x": false,
        "y": false,
        "z": false,
        "p": false,
        "d": false,
        "h": false,
        "r": false,
        "s": false
    }
}