I use these with a seeeduino nano (which has an onboard Grove I2C socket) and a second-hand USB power brick/cellphone charger in a food storage container as a cheap sensor node which students can deploy in class rooms and around their school.
The vendor has also been helpful and responsive to questions.
I look forward to finding new ways to use this node and about to purchase v2. You can find a case for this node here at www.thingiverse.com/thing:3620849 and a custom script here homeautomation.proboards.com/thread/523/joshs-thread-rfm-builts-cases .
Very impressed with the clever design, support and packaging / delivery. Very flexible with shipping options. Didn't hesitate to replace a bad batch of components and offer support on the (MySensors) forum.
Seller was polite and responsive and item quality seems good, but doesn't exactly work as advertised:
Expectations: item works in fixed led mode ("system OK") until HDD led totally stops, when it should enter led blinking mode ("reset warning mode") and eventually reset the computer.
Reality: system got reset multiple times even when there is regular HDD activity because the device isn't "sensitive" enough to detect it. The device goes into blinking mode ("reset warning mode") even when there is some HDD activity. You need HEAVY HDD usage to keep it from resetting.
Video: https://streamable.com/qwdxd Explanation: - Until 0:45 you can see normal HDD activity on my rig (top left purple-ish led blinking) but the watchdog warning led (bottom right red led) kept blinking (eventually it would have reset the computer) - Arround 0:45 i have to manually increase the HDD load so the warning mode gets disabled. - If left unattended (intended use for a mining rig) it would be reset-looping forever (not good) - Tried some workarrounds... scheduling a file read/write every minute or so, or using software to keep the HDD awake and in use (KeepAliveHD) and nothing worked. Again, you need HEAVY HDD loads every 1/2 minutes or so... not really working as expected
EDIT REPLY1: when i tried some workarrounds I considered solution (1), I considered that the led in parallel may be interfering with the device so i disconnected it but it didn't made a difference at all, so I reconnected it to record the video.
Really sorry you are not happy with the watchdog. The sensitivity of this board is extremely high for HDD LED activity detection. The threshold is 0.4V (measured it), it is much better than needed for HDD led blinks. HDD led voltage is checked every 0.4ms (been measured too, so it is real timing). Hence If HDD led will switch on or switch off at least once at 0.5ms the watchdog will know it. I am sure it is not possible to skip led flashes, which I can see on your video. So something really wrong here. For now I have two ideas: 1) May be your beautiful lamp\switch (the big one beside the cooler) is a complex device (not only led) and it brakes measurement circuit. Can you try the watchdog without your external lamp\switch. On-board watchdog lamp should blink every time watchdog detects HDD activity. Can you try it? 2) Micro-controller on the watchdog or the board is bad and we missed it during testing somehow. In any case I will send you another board if the first case will not help you. Thanks for your understanding and sorry.