Using Framos FSM:GO with GMSL Serializer/Deserializer on Toradex i.MX8

Technical Support
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The I2C device detection shows an interesting situation. The camera device 2-001a is detected and shows up in the device tree as imx678(1), but the i2cdetect scan on bus 2 shows no devices responding.

Analysis of the Issue

This pattern indicates that:

  1. Device Tree Overlay Applied Successfully: The presence of /sys/bus/i2c/devices/2-001a/name showing imx678 confirms the overlay is loaded correctly(2)
  2. I2C Communication Failure: The empty i2cdetect output suggests the physical I2C communication is not working(1)

When a device appears as UU in i2cdetect, it means kernel drivers are managing the device and blocking direct access(1). However, your scan shows -- which indicates no device response at all.

Hardware Connection Verification

Since you’re using the Dahlia Carrier Board, verify the camera connection to the correct MIPI-CSI connector. The Dahlia Carrier Board supports the MIPI CSI-2 interface and connects to the camera kits out-of-the-box, hardware-wise(2).

Troubleshooting Steps

  1. Check Power Supply Stability: Ensure stable power supply to both the SoM and camera module, as power supply fluctuations can cause inconsistent I2C communication(3).

  2. Verify Cable Orientation: The flat ribbon cable contacts must be on the correct side. The documentation specifically notes that “the flat ribbon cable (used to connect the carrier board and the camera adaptor) is fragile”(2).

  3. Test Different I2C Bus: Try scanning other I2C buses to ensure the camera isn’t connected to a different bus:

# i2cdetect -l
  1. Hardware Reset: Power cycle the entire system to ensure clean initialization.

Expected vs. Actual Behavior

According to the documentation, when the driver is activated, you should see the device appear as UU in the i2cdetect scan, indicating that kernel drivers are managing the device(1). The fact that you see -- suggests a hardware connectivity issue.

Similar Issues

Community reports show that some SoM units may have hardware variations affecting CSI functionality(3). The error pattern you’re experiencing (device tree detection but no I2C response) suggests a potential hardware-level connectivity issue rather than a software configuration problem.

Given that all hardware components are new and connections appear correct per documentation, this may indicate a hardware compatibility issue with this specific SoM unit or a subtle connection problem that requires careful re-verification of all cable connections and orientations.

Best regards, Toradex AI Assistant.

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