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Troubleshooting

Common issues and solutions for IRIV PiControl operation.

Power Issues​

Device Does Not Power Up via Terminal 1​

Symptoms:

  • No LEDs illuminate
  • OLED display remains blank
  • No response when connected to Terminal 1 power input

Possible causes and solutions:

  1. Power supply voltage out of range

    • Verify supply voltage is between 10V and 30V DC
    • Measure voltage at power supply output terminals
    • Check polarity (+ and - terminals)

  2. Blown fuse

    • Open enclosure and locate the 4A fuse on internal board
    • Check fuse continuity with multimeter
    • Replace with 4A fuse if blown
    • Investigate cause of overcurrent before reconnecting power

  3. Wiring error

    • Verify correct polarity (+ to +, - to -)
    • Check for loose terminal connections
    • Ensure adequate wire gauge for current capacity

Device Powers Up via USB-C but Not Terminal 1​

Symptoms:

  • Device works when powered by USB-C
  • No response when powered via Terminal 1

Solution:

  • Check the 4A fuse on the internal board
  • Fuse protects Terminal 1 input only; USB-C power bypasses the fuse

RS485 Communication Issues​

No Communication on RS485 Bus​

Check the following:

  1. A/B signal polarity

    • Verify A connects to A on all devices
    • Verify B connects to B on all devices
    • Reversed polarity will prevent communication

  2. Termination resistor configuration

    • Enable 120Ω termination only at both endpoints of the bus
    • Disable termination on intermediate devices
    • Check internal DIP switch position

  3. Baud rate mismatch

    • Verify all devices on bus use the same baud rate
    • Maximum supported: 500 kbps

  4. Device path

    • Confirm using /dev/ttyACM0 for RS485
    • Check device exists: ls -l /dev/ttyACM0

  5. GND connection

    • Connect 485-GND between devices for better noise immunity
    • Missing GND may cause intermittent communication errors

RS485 Works Intermittently​

Possible causes:

  • Electrical noise on the bus (add GND connection if missing)
  • Improper termination (verify only endpoints are terminated)
  • Cable length exceeds RS485 specification for baud rate

USB-C Boot vs Debug Confusion​

Cannot Access CM4 eMMC for Flashing​

Check boot/debug switch:

  1. Power off the device
  2. Open enclosure
  3. Locate Boot/Debug Mode Switch on internal board
  4. Set switch to Boot position
  5. Connect USB-C cable
  6. Use rpiboot utility on host computer

Cannot Access Serial Console​

Check boot/debug switch:

  1. Power off the device
  2. Open enclosure
  3. Locate Boot/Debug Mode Switch on internal board
  4. Set switch to Debug position
  5. Connect USB-C cable
  6. Open serial terminal at 115200 baud (default UART settings)

Note: The USB-C port function is determined by the physical switch position, not by software configuration.

OLED Display Issues​

OLED Display Blank or Not Showing IP Address​

Check the following:

  1. Configuration script not run

    • Run the setup script: 
      curl -L tinyurl.com/setup-iriv-picontrol | sudo bash
    • Reboot after script completes

  2. I2C not enabled

    • Verify I2C1 is enabled in /boot/config.txt or /boot/firmware/config.txt
    • Should contain: dtparam=i2c_arm=on

  3. Background script not running

    • Check if script exists: 
      ls -l /usr/local/bin/iriv_pi_control/background_script.py
    • Manually run script to test: 
      python3 /usr/local/bin/iriv_pi_control/background_script.py

  4. I2C device not detected

    • Check I2C bus for OLED at address 0x3C: 
      i2cdetect -y 1
    • Should show "3C" in the grid

User Button Does Not Cycle OLED Pages​

Verify:

  • Background script is running (see above)
  • Button is not held for 5+ seconds (this triggers shutdown instead)

Ethernet and Network Issues​

eth1 (10/100M Ethernet) Not Present​

Symptoms:

  • Only eth0 appears in ip addr output
  • eth1 missing

Solution:

  • Verify USB host is enabled in config.txt: 
    dtoverlay=dwc2,dr_mode=host
  • USB OTG mode should be disabled (commented out): 
    #otg_mode=1
  • Reboot after modifying config.txt

Cannot Access Device at iriv.local​

Check:

  1. Device and client computer on same network
  2. mDNS/Avahi service enabled on IRIV PiControl
  3. Try IP address directly instead of hostname
  4. Press User Button to view IP address on OLED display

Digital Input Issues​

Digital Input Not Responding​

Verify:

  1. Wet contact voltage applied

    • Digital inputs require external voltage source
    • Minimum: 3.0V DC
    • Dry contact switches will not work

  2. Correct wiring polarity

    • Positive signal to DI+ terminal
    • Ground to DI- terminal

  3. Voltage within range

    • Minimum: 3V
    • Maximum: 50V

Analog Input Issues​

Analog Input Reads Zero in Current Mode​

Check:

  1. DIP switch enabled

    • Internal Analog Input Mode Switch must be set to current position
    • DIP switch ON to enable 250Ω shunt resistor

  2. ADC gain setting

    • Use gain=2 for 0-20mA measurement

All Analog Channels Must Be Same Mode​

Remember:

  • Voltage/current mode applies to all four channels
  • Cannot mix voltage and current measurement
  • Internal DIP switch sets mode for AI0, AI1, AI2, and AI3 simultaneously

Source(s):

  • IRIV PiControl CM4 User Manual, Rev 1.3, Nov 2025
  • IRIV PiControl Node-RED Tutorial (my.cytron.io)