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SUNLU AMS Heater Auto-Vent Controller - Build Guide

This guide will walk you through assembling and soldering the PCB for the SUNLU AMS Heater Auto-Vent Controller.

What You'll Need

Tools

  • Soldering iron (temperature-controlled, 300-350°C recommended)
  • Solder (60/40 or 63/37 tin-lead, or lead-free SAC305)
  • Flux (rosin-based or no-clean flux)
  • Wire cutters/flush cutters
  • Wire strippers
  • Small needle-nose pliers
  • Multimeter (for testing continuity)
  • Helping hands or PCB holder (optional but recommended)
  • Isopropyl alcohol and brush for cleaning flux residue (optional)

Components (Included in DIY Kit)

  • 1x Custom PCB (V1.0 or V2.0)
  • 1x Seeed XIAO SAMD21 or RP2040 microcontroller
  • 1x ADS1115 16-bit ADC module
  • 1x ACS758 current sensor module
  • 1x 5V feedback servo motor
  • 1x 470µF electrolytic capacitor
  • 1x Mini illuminated momentary pushbutton (V2.0 only)
  • 1x C8 panel mount power inlet
  • 1x DC power socket for 5V
  • 1x AC power cable with C7 plug
  • 1x Data cable with ferrite core (assembled)
  • Headers and terminals:
    • 2x 7-pin headers (for SAMD21/RP2040)
    • 1x 10-pin header (for ADS1115)
    • 2x 3-pin 90° right-angle headers (for ACS758)
    • 1x 4-pin 90° right-angle header (for servo)
    • 1x 2.54mm 2-position screw terminal (for PCB power)
    • 1x 5mm 2-position screw terminal (for ACS758)
  • Wire leads for 5V socket

Safety First

  • Always unplug the dryer before working on the controller
  • Work in a well-ventilated area when soldering
  • Use eye protection
  • Don't touch the soldering iron tip (it's hot!)
  • Let components cool before handling
  • Keep a fire extinguisher nearby

Assembly Order

It's easiest to solder components in order from shortest to tallest. This allows the PCB to sit flat while soldering.

Step 1: Inspect the PCB

  1. Examine the PCB for any damage or manufacturing defects
  2. Identify component placement markings and labels
  3. Note the orientation markers for polarized components

Step 2: Solder the Screw Terminals

2.54mm Terminal (PCB Power Input)

  1. Insert the 2.54mm 2-position screw terminal into the PCB
  2. The terminal openings should face outward from the board
  3. Flip the PCB and solder both pins
  4. Ensure good solder joints with shiny, volcano-shaped fillets

5mm Terminal (ACS758 Connection)

  1. Insert the 5mm 2-position screw terminal
  2. Orient the terminal openings as marked on the PCB
  3. Solder both pins from the back
  4. Trim any excess lead length

Step 3: Solder Pin Headers

XIAO Microcontroller Headers (2x 7-pin)

  1. Insert both 7-pin headers into the PCB where marked
  2. Use tape or helping hands to hold them perpendicular
  3. Solder one pin on each header first
  4. Check alignment - reheat and adjust if needed
  5. Solder remaining pins
  6. Do not install the XIAO yet - it will be inserted after programming

ADS1115 Header (10-pin)

  1. Insert the 10-pin header into the ADS1115 module first
  2. Place the ADS1115 with header onto the PCB
  3. Solder one pin while holding the module flat against the PCB
  4. Check alignment and solder remaining pins
  5. The ADS1115 module should now be permanently attached

ACS758 Headers (2x 3-pin 90° right-angle)

  1. Insert the two 3-pin right-angle headers into the ACS758 module
  2. The headers should point straight out from the module
  3. Solder all pins on the ACS758 module side
  4. Do not attach to PCB yet - the ACS758 will connect after wiring

Servo Header (4-pin 90° right-angle)

  1. Insert the 4-pin right-angle header into the PCB
  2. Orient the header so the connector points in the correct direction
  3. Solder all 4 pins from the back of the PCB
  4. This header will connect to the servo cable

Step 4: Solder the Capacitor

470µF Electrolytic Capacitor

  1. Important: Identify the negative lead (shorter leg, marked stripe on body)
  2. Match the negative lead to the white half-circle marking on the PCB
  3. Insert the capacitor with correct polarity
  4. Bend leads slightly to hold it in place
  5. Solder both leads from the back
  6. Trim excess lead length with flush cutters
  7. Double-check polarity - reversing this can damage the capacitor

Step 5: Install Power Connectors

C8 Panel Mount Power Inlet

  1. Insert the C8 inlet into the marked location on the PCB
  2. Solder all connection points
  3. Ensure mechanical stability for repeated plug/unplug cycles

5V DC Power Socket

  1. Prepare the wire leads (included in kit)
  2. Strip approximately 3-4mm of insulation from each lead
  3. Tin the wire ends with solder
  4. Insert into the socket terminals and solder
  5. Connect the other ends to the appropriate pads on the PCB
  6. Observe correct polarity (+ and - markings)

V2.0 Only: Illuminated Pushbutton

  1. Insert the mini illuminated momentary pushbutton into the PCB
  2. Note the LED polarity if applicable
  3. Solder all connection points
  4. Test button mechanical action

Step 6: Prepare Cable Connections

AC Power Cable

  1. The AC power cable with C7 plug should be pre-assembled
  2. Connect to the C8 inlet on the PCB
  3. Route the other end to your dryer's heater power

Data Cable with Ferrite Core

  1. The data cable should come pre-assembled
  2. This connects the servo feedback signal
  3. Route as needed during final installation

Servo Connection

  1. Connect the servo cable to the 4-pin right-angle header
  2. Observe proper orientation (signal, power, ground)
  3. The servo should have its own connection point

Step 7: ACS758 Current Sensor Wiring

  1. Mount the ACS758 module in the enclosure (not on PCB)
  2. Use the 3-pin right-angle headers to connect to the PCB
  3. Connect power and signal wires between ACS758 and PCB
  4. Wire the AC power through the ACS758 current sense path
  5. Ensure proper wire gauge for current capacity (minimum 18 AWG)

Step 8: Inspection and Cleaning

  1. Visually inspect all solder joints
    • Look for cold solder joints (dull, grainy appearance)
    • Check for solder bridges between pins
    • Verify all pins are soldered
  2. Use multimeter to check for shorts between power and ground
  3. Clean flux residue with isopropyl alcohol if desired
  4. Let the board dry completely

Step 9: Initial Testing (Before Programming)

Continuity Checks

  1. With power OFF, check continuity between:
    • Ground connections
    • Power rail connections
  2. Verify NO continuity between power and ground
  3. Check all header pins for proper connection

Visual Inspection

  1. Ensure no loose wires or components
  2. Verify all polarized components are correctly oriented
  3. Check that no solder bridges exist

Step 10: Programming the XIAO

Install Arduino IDE and Libraries

  1. Download Arduino IDE from arduino.cc
  2. Install SAMD21 or RP2040 board support
  3. Install required libraries:
    • Adafruit_ADS1X15 (for ADS1115)
    • Servo library
    • FlashStorage (SAMD21) or EEPROM library (RP2040)

Upload Firmware

  1. Connect XIAO to computer via USB-C
  2. Open the AutoVent firmware sketch
  3. Select correct board (XIAO SAMD21 or XIAO RP2040)
  4. Select correct COM port
  5. Click Upload
  6. Wait for upload success message

Insert XIAO into PCB

  1. After programming, carefully insert the XIAO into the 7-pin headers
  2. Ensure correct orientation (USB port should face outward)
  3. Press firmly but gently until seated
  4. The XIAO should be level with the PCB

Step 11: Power-On Testing

First Power-Up

  1. Connect 5V power supply (2A minimum recommended)
  2. Observe the LED indicator
  3. The LED should illuminate (exact pattern depends on mode)
  4. Listen for servo movement during initialization

Serial Monitor Testing

  1. Connect XIAO to computer via USB
  2. Open Arduino Serial Monitor (115200 baud)
  3. Observe startup messages
  4. Verify current sensor readings
  5. Check for any error messages

Step 12: Calibration

Servo Calibration (Automatic)

  1. The servo automatically calibrates at startup
  2. It will move to open and closed positions
  3. LED will flash during calibration
  4. Wait for calibration to complete

Current Threshold Learning (Manual)

  1. Press and hold button for 5+ seconds to enter learning mode
  2. Follow LED prompts:
    • Phase 1: Ensure dryer is OFF, LED flashes fast
    • Phase 2: Turn dryer ON (heater + fan), LED flashes fast
    • Phase 3: Turn heater OFF (fan only), LED flashes fast
  3. After completion, LED shows 3 long flashes
  4. Thresholds are saved to memory

Troubleshooting

LED Not Lighting

  • Check capacitor polarity
  • Verify power connections
  • Check XIAO insertion orientation
  • Measure 3.3V at XIAO pins with multimeter

Servo Not Moving

  • Verify servo connection to 4-pin header
  • Check 5V power supply capacity (minimum 2A)
  • Test servo feedback signal with serial monitor
  • Ensure servo cable is not damaged

Current Sensor Not Reading

  • Verify ACS758 power connections
  • Check I2C connections to ADS1115
  • Test with serial monitor output
  • Ensure AC power is flowing through sensor

ADS1115 Not Found Error

  • Check I2C SDA and SCL connections
  • Verify ADS1115 module is properly seated
  • Check for solder bridges on I2C pins
  • Confirm I2C address (default 0x48)

Erratic Readings

  • Ensure proper grounding throughout
  • Check for loose connections
  • Verify ferrite core is installed on data cable
  • Check AC power cable routing away from sensitive signals

Component Orientation Reference

Polarized Components

  • 470µF Capacitor: Negative lead (shorter, marked stripe) goes to marked pad
  • XIAO Microcontroller: USB port should face outward/upward
  • ADS1115: Component side faces up, pins insert through PCB
  • 5V DC Socket: Observe + and - polarity markings

Connector Orientations

  • Screw Terminals: Openings face outward for easy wire access
  • Right-Angle Headers: Verify direction matches PCB silkscreen
  • Servo Header: Connector should be accessible from enclosure opening

Final Assembly Tips

  1. Take your time: Rushing leads to mistakes and cold solder joints
  2. Use adequate flux: Helps solder flow and creates better joints
  3. Proper temperature: Too hot damages components, too cold creates poor joints
  4. Clean tip regularly: Wipe soldering iron on wet sponge frequently
  5. Secure the board: Use helping hands or vise to hold PCB steady
  6. Test as you go: Check each connection with multimeter before moving on
  7. Document changes: If you modify anything, write it down

Next Steps

After completing the build:

  1. Review the User Guide for operation instructions
  2. Check the Technical Specifications for detailed information
  3. Install in your 3D printed enclosure
  4. Mount in your SUNLU AMS dryer
  5. Run the learning mode to calibrate for your specific dryer

Additional Resources

  • Firmware: Available on GitHub (link to be added)
  • 3D Print Files: Available on MakerWorld (search "SUNLU AMS Heater AutoVent")
  • Schematic: Included with PCB or available online
  • Video Build Guide: Coming soon

Support

If you encounter issues during the build:

  • Double-check all solder joints and component orientations
  • Review the troubleshooting section
  • Consult the technical specifications
  • Contact support through the shop

Remember: This guide is a starting point. Your specific build may require adjustments based on your PCB version and component variations.