A Recent Hardware Tinkering Compilation - FPGA ZYNQ Dev Board, JDCloud, LicheePi 4A, 3965u...

Recently I’ve been playing around with some hardware I already had or just picked up during my spare time. Individually, none of them felt worth a full write-up, so I figured—why not just compile them into one post and show them off together?

Below is the timeline in the order I tinkered with them.

Some unknown rk3399 dev board

Can’t find the photo anymore…

I bought this board because it claimed to support USB OTG and HDMI IN, thinking it’d be perfect for a PiKVM setup. Turns out, HDMI IN only works under Android. The capture chip is a TC358743G, which theoretically supports Linux, but after multiple failed attempts to port the Android dtb file, I gave up. On top of that, I discovered occasional kernel panics under Linux (memory errors during stress tests), making the system unstable. Eventually, I sold it off.

Later, I noticed the N1 box had dropped in price, so I grabbed one and finally made my PiKVM dream come true.

JDCloud Luban Router

A year ago, I joined JDCloud’s PCDN program and got five Luban routers for free. The one at school now looks like this after I ripped off the case.

Luban router with case removed

The stock firmware obviously couldn’t meet my needs, but the company actively blocks attempts to flash third-party ROMs—after all, if everyone flashes custom firmware, they can’t run PCDN. A quick search online showed that all known flashing methods no longer work on the latest firmware.

So I went straight for hardware: opened it up, used a CH341A programmer to flash and downgrade the SPI chip. After downgrading, I exploited a vulnerability to SSH in and flash a custom u-boot (though there’s no compatible Breed recovery). From there, flashing OpenWRT was straightforward. Nothing too special—binaries you might need are here.

CH341A programmer and clip for non-invasive flashing

Always back up the original firmware before writing anything—the factory partition contains device-specific calibration data (EEPROM). Flashing someone else’s backup will mess up your signal. Don’t ask me how I know—my Xiaomi 3A taught me that lesson the hard way.

Unknown 3965u mining board (silk-screened as PANDA MINER, so sometimes called the “Panda Miner”)

After selling the RK3399, I just felt like I was missing some new toy. Then I saw a Bilibili video about an 847 control board, and found out there’s an upgraded version—the 3965u mining board—for just 65 RMB. How could this not beat my heirloom j1900?

3965u mining board

Overall, x86 is way more fun than ARM—thanks to UEFI, I can try out all kinds of operating systems.

Ran a stress test and noticed this 15W TDP CPU only drew about 7W under full load. At first I thought it was a BIOS limitation, so I tried every trick to modify the BIOS—no luck. Then I realized the 3965u doesn’t support turbo boost. It’s stuck at 2.2GHz, and likely capped by design at that power level. So I gave up.

(P.S. The BIOS here is clearly half-baked—full of useless options.)

But of course, an unexpected issue hit: the board worked perfectly at first, but after two days, HDMI suddenly stopped outputting anything. Everything else was fine (I could still SSH in over the network). After some research, I found out these mining boards often have faulty HDMI ports. Replacing the port might fix it, but I couldn’t borrow a proper soldering iron from friends… So I started down a rabbit hole.

The Dumpling I Made for the Vinegar – EBAZ4203 (ZYNQ 7010 FPGA Dev Board)

After buying the soldering tools, I felt like I had to try something else—otherwise it’d be a waste. (Spoiler: it turned out even more wasteful)

Coincidentally, Bilibili recommended me this ZYNQ 7010 FPGA mining board. On a whim, I decided to try my hand at FPGA.

EBAZ4203

I gambled 30 RMB on a broken board from Xianyu (China’s secondhand marketplace). Plugged it in—no power LED lit up. After some debugging, I found that supplying 5V directly to VCC made it boot fine, but the 12V-to-ground path was open. Haven’t figured out the exact fault yet—most online guides are for the EBAZ4205, which seems slightly different.

Next step: maybe get an FT232HL for JTAG debugging.

LicheePi 4A RISC-V Dev Board

I got a LicheePi 4A for free because there’s a school project involving RISC-V and Android.

LicheePi 4A

The official open-source Android firmware is full of bugs and barely compiles. The stable version requires direct contact to obtain—another classic case of “delayed open-source.” Honestly, I’d rather wait for Google and mainline Linux to catch up.

I also tried flashing Debian. Linux support for RISC-V is… kind of usable, at least.

If anything interesting comes up, I might write another blog post. But given it’s a school project… probably not.

Aftermath

Turns out, I couldn’t desolder the HDMI port on that 3965u board with my iron… Then, while cleaning off some rosin, I sprayed a bit of WD40—and magically, it started working again… WTF, I should’ve tried WD40 earlier

So I went through all the trouble of making dumplings, only to realize—what I really wanted was a spoonful of soy sauce.