HMUF02 Troubleshooting: LED Drivers, Reset Switch & Thermals

This page documents the known issues, hardware variations, and fixes specific to the HMUF02 board family.

1. Silent Substitution of Counterfeit / Non-Qualcomm Chipsets

The Issue:

The greatest hazard with HMUF02 sticks is that late production batches often reuse the exact same plastic shell and packaging while replacing the Qualcomm MSM8916 with an ASR1802 or ZX297520 chipset. These clone chips cannot run ARM64 Linux or OpenStick firmware.

Diagnosis:

Connect the factory device to a PC and run:

adb shell getprop ro.board.platform

If it returns msm8916, your stick is authentic.
If it returns asr1802, zx297520, or sp9820e, the board is incompatible with OpenStick.

2. Inverted Power & Status LED GPIOs

The Issue:

On standard OpenStick Debian kernels, the HMUF02’s main status LED may remain unlit, or the 4G LED might turn solid red instead of green upon establishing a network connection. This occurs because the HMUF02 routes the power indicator to GPIO 3 with Active Low polarity, whereas reference UFI001B boards expect Active High on GPIO 0.

Fix / Workaround:

Create a custom systemd startup service to configure the LED properly:

[Unit]
Description=HMUF02 LED Fix
After=network.target

[Service]
Type=oneshot
ExecStart=/bin/sh -c 'echo 0 > /sys/class/leds/red:power/brightness && echo 1 > /sys/class/leds/green:power/brightness'

[Install]
WantedBy=multi-user.target

Enable the service:

sudo systemctl daemon-reload
sudo systemctl enable --now hmuf02-leds.service

3. Stuck or Misaligned Reset Switch

The Issue:

The mechanical reset button on the PCB is aligned beneath a thin plastic actuation pin. On some cheap shells, the button can become physically stuck in a depressed state when the casing is snapped together, causing the stick to boot perpetually into recovery mode or reboot every 10 seconds.

Fix / Workaround:

Open the two plastic shell halves with a plastic spudger.
Inspect the miniature SMD tactile switch on the board. Ensure the metal dome clicks freely.
If necessary, trim 0.5mm off the interior plastic pin using an X-Acto knife or utility blade to prevent mechanical binding.

4. RF Signal Attenuation from Stock Ceramic Antenna

The Issue:

The HMUF02 uses a very small onboard ceramic chip antenna for 4G LTE. In indoor environments or areas with weak LTE signals, speeds can drop below 1 Mbps and the modem may disconnect frequently.

Fix / Workaround:

Solder a 5cm IPEX/u.FL coaxial pigtail to the antenna feed pad near the edge of the board (see HMUF02 Pinouts) and attach an external 3dBi or 5dBi rubber ducky antenna. Community tests report an immediate 15–20 dBm improvement in RSRP signal quality.

Frequently Asked Questions — HMUF02 (HMUF02-V05)

Is the HMUF02-V05 board compatible with OpenStick Debian Linux?

Yes! Genuine HMUF02-V05 (and HMUF02-MB-V01/V02) boards powered by the Qualcomm MSM8916 (Snapdragon 410) with 4GB eMMC storage are fully supported by OpenStick Debian and lk2nd.

How do I check if my HMUF02 is genuine MSM8916 or an ASR1802 clone?

Open the shell to verify the HMUF02-V05 silkscreen and Qualcomm MSM8916 chip, or run adb shell getprop ro.board.platform to confirm it outputs msm8916 instead of asr1802 or zx297520.

👉 Ready to flash? Download the 1-Click OpenStick Debian Installer or browse Verified Store Links.