DIY Welding Positioner Controller

Touchscreen controller for a single-axis TIG/MIG welding rotator.

Built for the GUITION JC4880P443C 4.3" touch display board — ESP32-P4, 800×480 landscape, ST7701S MIPI-DSI and GT911 capacitive touch.

Try the Windows simulator · Firmware downloads · Builder guide · Watch the hardware demo

The image shows the current V5 interface with example data. The hardware demo shows an earlier UI on the existing machine.

GUITION JC4880P443C 4.3" touch display board is the project's supported hardware target. The display, touch and expansion-header wiring are configured for this board; another ESP32-P4 display board may need different drivers and pins.

Board illustration and pin reference above. The product illustration shows vendor software/features; this firmware uses the ESP32-P4 side and has no Wi-Fi/BLE control. Use the hardware guide for actual project wiring and reserved pins.

• Continuous, Jog, Pulse and Step rotation, with a configurable countdown before starting.
• Workpiece speed within 0.001–3.0 RPM, subject to geometry, calibration and the configured ceiling. The screen shows the effective minimum; for example, microstep 4 with a 300 mm part requires at least 0.004 RPM at the retained 20 Hz floor.
• Panel potentiometer, physical direction switch and optional foot pedal control.
• 16 saved programs, with speed, direction, diameter and mode settings.
• Physical E-STOP input, driver-alarm monitoring and guarded reset.
• Guided setup and calibration, touch diagnostics and a USB-C live mirror.
• Optional idle screen saver in the V5 design, with touch-to-wake and a Display preview.

v2.2.1 makes the foot pedal work in every configuration: GPIO33 switch start/stop always, ADS1115 analog pedal speed when present, panel-potentiometer fallback otherwise. Release notes · Changelog.

v2.2.0 adds the idle screen saver, flat UI refinements and further motion/input/storage fixes, retaining LVGL 9.6 and FastAccelStepper 1.4. Release notes · Changelog.

1. Download the Windows x64 simulator ZIP above.
2. Extract all files into one folder.
3. Open Start Simulator.cmd and use the mouse as the touchscreen.

No hardware or development tools are required. It runs the actual LVGL UI and production control code with simulated hardware. It cannot drive a real motor. Simulator instructions.

Motor/gearbox and drivetrain references. Match the driver's current and microstep switches to your motor and touchscreen settings; the firmware supports 1/4, 1/8, 1/16 and 1/32 microstepping.

Before powering the motor: verify STEP/DIR/ENA wiring, E-STOP input polarity and driver configuration using the hardware guide. Firmware expects GPIO34 HIGH when healthy, LOW on fault, and ENA HIGH to disable. A bare NC contact to ground does not meet that input contract.

For HF-start TIG welding, put the controller, driver and motor PSU inside the same grounded metal enclosure. EMI installation guide.

The original project diagram now uses the V5 graphite/orange design, with corrected pin references, DIP notes, RPM limits and input requirements. Follow the electrical wiring guide for driver terminal selection, logic interface and ground connections. ESP32 GPIO is 3.3 V logic; never connect 5 V or motor-supply voltage to it.

The NC E-STOP button is retained in the diagram. Its dashed interface block specifies the HIGH-healthy / LOW-fault input required by the existing firmware; a bare NC contact to GND produces the opposite polarity. The driver routing shown is common-cathode. Dashed blocks specify interface requirements, not verified installed circuitry. Confirm the actual interface and ENA polarity on the assembled controller; physical stop time remains unmeasured. Input truth table and measurement procedure.

For HF-start TIG welding, put the ESP32-P4 display/controller, stepper driver and motor PSU inside the same grounded metal enclosure. This is part of the project's installation requirements.

• Bond the enclosure to protective earth using a suitable connection.
• Separate motor/power wiring from GPIO, ADC, I2C, pedal and E-STOP cables.
• Use shielded external cables and enclosure-side shield termination where appropriate; add ferrites if interference remains.
• Repeat HF-start checks after changing firmware, wiring, cable routing or the enclosure.

Earlier hardware testing worked during TIG welding after the shared grounded enclosure was installed. This is historical field experience; it does not qualify v2.2.0 or measure its physical stop response. EMI installation and test details.

Choose a release, debug or mirror flashing bundle from Downloads. Follow FLASHING.md, including first-install versus application-update instructions. Application images belong at 0x10000, never zero. Check the supplied SHA-256 checksums.

For a source build, install PlatformIO and use:

git clone https://github.com/catorendal-a11y/DIY-Welding-Positioner-ESP32-P4.git
cd DIY-Welding-Positioner-ESP32-P4
git checkout v2.2.1
pio run

The flashing guide covers upload, serial ports and variant selection. On first use, follow Setup Wizard; existing valid settings are retained. Getting started · Setup instructions.

New installations open Setup Wizard after boot. Existing valid settings and programs are retained; run it again from Settings → Setup Wizard.

1. Motor: match driver timing and microsteps to the physical driver, set limits, then SAVE & APPLY.
2. Direction: hold CW/CCW, observe the workpiece, flip direction if needed and confirm it while idle.
3. Calibration: align a mark, complete MOVE 360, measure, apply the correction, complete VERIFY 360, measure again and save only after verification passes.
4. Function check: press/release the physical E-STOP, explicitly reset to idle, test START and normal STOP, then confirm the observed physical behavior.

Completion waits for its settings-save receipt. It does not start motion, measure physical stop time or certify wiring. Every wizard screen · Calibration guide.

Set speed and direction while idle, choose a mode or saved program, then press START. STOP requests normal deceleration. The physical E-STOP input inhibits ENA and latches a fault; clearing/resetting a fault never starts rotation.

Calibration guides you through Align → Measure → Verify → Save. The correction stays temporary until a completed verification meets tolerance and its save succeeds. New Program separates run mode, available modes, exact RPM and mode settings.

Calibration screens · Program editor screens · USB mirror.

v2.2.0 includes cancelled-countdown guards, motion bounds/timeouts, pedal takeover, program direction and verified saves. Logic review. LVGL 9.6 UI refinements improve text placement, status updates and exact motor-settings entry while preserving the flat design.

Validation covers 459 native/control/speed/storage tests, packaging regressions, upstream RMT encoder checks, Linux/Windows simulator checks, a zero-failure layout audit and three firmware builds. Release binaries come from the exact validated master CI commit. Release validation.

• Single axis; no encoder feedback. RPM/progress are calculated, so calibration requires real measurement.
• The owner confirms the assembled controller functions work, including the foot pedal: on 2026-10-05 the ADS1115 answered the boot scan at 0x48 and GPIO33 switch + analog pedal speed were verified working on the assembled machine (master build with runtime pedal source selection, unreleased). This is functional feedback; no measured stop-time or HF qualification is claimed.
• Earlier TIG field experience supports the grounded-enclosure requirement; it does not qualify the latest firmware or establish a physical stop-time guarantee.

Built one? Share your controller photos, driver/motor configuration and firmware version in an issue. That helps other builders reproduce the setup.

MIT licensed. See LICENSE; dependencies and fonts retain their own notices.