A complete network cable locator / link keep-alive tester that costs about RMB 6 to replicate. Built around the CH32V003 in the SOP-8 package, it wakes on cable insertion, pulses link-activity signals, and drops to a 9 uA deep-sleep state when the cable is unplugged.
| Platform | LCEDA Open Hardware (oshwhub.com) |
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| Author | mimimi2024 |
| License | CC BY-NC-SA 4.0 |
| Silicon | WCH CH32V003 (SOP-8) |
| What it does | Plug the tester into an Ethernet port and it automatically emits link-activity pulses so you can identify the cable by watching the switch port LED — no PC, no second person, no stripping shielded cables to test them. |
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| Why it is interesting | It pushes the 10-cent RISC-V MCU to its limits: only 4 GPIOs used on the SOP-8 package, one PWM output remapped from TIM2_CH3, one edge-triggered wake-up on the network coil, and firmware-driven power states down to 9 uA. |
| Firmware | Open source on GitHub (wxwsl/NetSprite). A single-button UI with persisted duty-cycle settings, plus a developer mode for tuning. |
| For you | A compact reference for ultra-low-power CH32V003 designs: wake-on-signal, deep sleep budgeting, and squeezing a useful product into a SOP-8 package with a 4-IO budget. |
Can I use this design commercially?
The project is released under CC BY-NC-SA 4.0 — non-commercial. Check the project page and the license text before any use, and credit the author.
Which debugger do I need to re-flash it?
A WCH-LinkE via the single-wire SDI pin, as with all CH32V003 boards.