Is your nRF52840 MDK USB Dongle stubbornly displaying a single light? We understand the frustration. This guide provides a clear path to resolving this common issue, explaining what those LEDs mean and offering step-by-step solutions.
The LEDs on your nRF52840 MDK USB Dongle communicate its status. Understanding their patterns is the first step to diagnosis.
LED Color
State
Likely Meaning
Green
Solid
Power is good, but no data exchange with your computer. This is the typical “single light” issue.
Red
Blinking Slowly
Device Firmware Update (DFU) mode. Ready for firmware updates.
Red
Blinking Rapidly
Firmware update in progress. Do not interrupt!
Red
Solid
Potential hardware or firmware issue.
None
Off
No power. Check connections and power source.
Green (Two)
Two solid green
Application mode rather than DFU mode.
Green
Zigbee Light Switch- Connected
Device successfully connected to the Zigbee network (for Zigbee setups)
Green
Zigbee Coordinator- Active
Zigbee network is actively running.
Green
Zigbee Light Bulb- Joined
Light bulb has joined the Zigbee network.
Red
Zigbee Light Switch- Paired
Light switch and light bulb have successfully paired.
Entering DFU Mode (The Most Common Fix)
DFU mode is essential for firmware updates and often resolves the single green light issue. Here’s how to enter DFU mode on various operating systems:
Step 1: Locate the RESET/BOOT Button: This tiny button often sits next to the SW1 button.
Step 2: Press and Hold RESET/BOOT: Keep this button pressed.
Step 3: Connect to USB (While Holding RESET/BOOT): While still holding the button, plug the dongle into your computer’s USB port.
Step 4: Release RESET/BOOT (After a Delay): Hold the button for a few seconds after connecting, then release. A blinking red LED confirms DFU mode.
[A short, high-quality video demonstrating this process would be embedded here. Please provide the video link so it can be properly embedded in markdown format.]
What if I see two solid green LEDs? This likely means you released the RESET button too early and the application started instead of entering DFU mode. Try the steps again, focusing on holding the button a bit longer after connecting. Sometimes, a double-click of the RESET/BOOT button before connecting can also initiate DFU mode, depending on the firmware version.
Troubleshooting Other Causes
If DFU mode doesn’t solve the problem, explore these other potential causes:
Driver Installation
Incorrect or outdated drivers can prevent your computer from recognizing the dongle.
Check Device Manager (Windows) or System Information (macOS): Look for errors related to the dongle (e.g., a yellow exclamation mark).
Install/Reinstall Drivers: Download the latest nRF52840 MDK USB Dongle drivers from the official Nordic Semiconductor website. Uninstall any existing drivers first, then install the new ones. Restart your computer after installation.
Firmware Issues
Outdated or corrupted firmware can also cause problems.
Check Firmware Version: Use nRF Connect Programmer to check the dongle’s current firmware version.
Update Firmware: Download the latest firmware from the Nordic Semiconductor website. Use nRF Connect Programmer to flash the new firmware onto the dongle. Follow the instructions provided with the firmware download.
Hardware Failure
While less likely, hardware problems can occur. If other solutions fail:
Try Different USB Ports and Cables: Rule out cable or port issues. Try both USB 2.0 and 3.0 ports.
Test on Another Computer: If possible, test on a different machine to isolate the problem.
Contact Makerdiary Support: If you suspect a hardware fault, contact Makerdiary support for assistance.
Advanced Troubleshooting (Optional)
Experienced users can consider these advanced steps:
JTAG Debugging: A JTAG debugger allows for more in-depth hardware-level debugging and can sometimes force the dongle into DFU mode. Consult the documentation for your specific JTAG debugger.
By systematically working through these steps, you should be able to resolve the single-light issue on your nRF52840 MDK USB Dongle. While this guide covers the most common solutions, ongoing research continues to refine our understanding of these devices. Please share your experiences and feedback in the comments below, as it may help others and contribute to the broader knowledge base.
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