I received the BIQU Panda Lungs today for my P1S but there are no installation instructions included. Also, one QR code on the box goes to your new Neo Wiki but there is nothing there for the Panda Lungs. Please reply with installation instructions. I have no idea how the included bracket is used and how I turn the air purifier on.

Hello everyone,

I am facing a deeply perplexing issue with my stepper motor setup on a BIGTREETECH Octopus Pro board, and I desperately need technical insights. I have exhausted standard online guides and firmware troubleshooting.

1. Hardware Specifications

• Motherboard: BIGTREETECH Octopus Pro V1.1 (MCU: STM32H723ZE variant)
• Stepper Driver: TMC2209
• Stepper Motor: 17HE15-1504S (NEMA 17, 1.5A)
• Firmware: Marlin
• Power Supply: 24V DC MeanWell PSU

2. Core Symptoms & Behavior

• Under 24V Power Input: The motor exhibits a very strong holding torque (the shaft locks up rigidly and cannot be rotated by hand). However, when I send a movement command (e.g., G1 X20 F60) via Pronterface, the motor does absolutely nothing. There is no rotation, no vibration, and no audible frequency hum whatsoever. It remains completely locked.
• Under USB 5V Power Only (24V disconnected): If I cut the 24V power supply and only power the logic via USB-C, sending the exact same movement command results in a distinct, directional pulse/force felt on the motor shaft. While it lacks the high-voltage torque to fully rotate, the STEP/DIR signal sequence is clearly reaching the motor coils. The moment 24V is reapplied, it returns to a completely silent, stationary lock.

3. Troubleshooting Already Conducted

• Endstop Interferences (M119): Initially, all min endstops were stuck on TRIGGERED due to logic configuration. I inverted them in Configuration.h (X_MIN_ENDSTOP_HIT_STATE LOW), and running M119 now correctly returns open for all axes.
• Command Sequence: To bypass any firmware safety limits during testing, I used: PlaintextG92 X0 M211 S0 G91 G1 X20 F60
• Driver Modes & Physical Jumpers: 1. UART Mode: Set #define X_DRIVER_TYPE TMC2209 in Marlin. Placed a single jumper on the designated CS-CS pin according to the BTT manual. M122 continuously outputs Error: All LOW. 2. Standalone Mode: Changed firmware to TMC2209_STANDALONE. Removed UART jumpers and placed jumpers on MS1/MS2 for hardware 16-microstepping interpolation, and shorted the SLP-RST pins.
  • Result: The behavior is completely identical in both configurations (locked solid on 24V with zero movement/vibration, but directional pulses felt under USB 5V).
• VREF Tuning: Adjusted the potentiometer from 0V up to 1.0V (and briefly up to 1.7V to check protection cutoffs). The holding torque intensity scales properly with VREF adjustments, but no movement is triggered.
• Wiring Verification: Verified coil pairs using a multimeter. Phase A is mapped to pins 1-2, and Phase B is mapped to pins 3-4. The fact that directional pulses are felt during the USB-only test confirms the wiring order delivers the phase sequence.
• Thermal Sensors (M105): Since I am testing the motor standalone without hotend/bed thermistors connected, M105 reports T:-15.00. However, Marlin accepts commands and executes stepping routines normally without throwing a hard heater kill halt.

4. The Main Question

Why does the stepper driver successfully pass the STEP/DIR pulses to the motor coils when running on low USB 5V voltage, but completely ignore/filter out the high-frequency step pulses and remain in a dead holding lock the moment 24V VM (Motor Power) is supplied?

Could this point to a physical hardware defect on the Octopus board (such as a failed level shifter or isolating optocoupler), a cooked driver internal gate logic, or a critical timing mismatch in Marlin regarding the high-speed STM32H723 clock cycles?

Any testing methods, firmware overrides, or hardware diagnoses would be highly appreciated. Thank you.

I've got a bit of a strange situation and I'm hoping someone can help.

Long story short, I bought this printer second-hand. It came running Klipper from a Raspberry Pi, and the previous owner had already upgraded the motherboard to a BIGTREETECH SKR Mini E3 V3.0.

Unfortunately, I can't keep using the Raspberry Pi because I don't have Wi-Fi where my printer is, and to be honest, the Raspberry Pi/Klipper setup is just too complicated for me. I'd much rather run Marlin directly from the printer using an SD card. At the moment, when I unplug the Raspberry Pi, the printer just shows a blue screen because there's no firmware on the board.

I did try following a few guides to make my own Marlin firmware, but I have absolutely no idea what I'm doing. 😅 This is my first 3D printer, so I'm completely new to all of this.

My printer has:

• Ender 3
• BIGTREETECH SKR Mini E3 V3.0
• Creality Sprite Extruder Pro Kit
• CR Touch

I'm hoping someone has a firmware.bin or a similar Marlin firmware that I can simply download, copy to an SD card, and flash to get the printer back to running Marlin.

I know it probably won't be a perfect match, but if anyone has a firmware for a similar setup that I could try, I'd really appreciate it. Even if it needs a few small changes later, I'd just like to get the printer running again.

If it helps, I can upload photos of the printer, motherboard, and wiring.

Thanks in advance! Any help would mean a lot.

I recently started using klipper to print faster and more efficiently, and after a while it started disconnecting randomly, then it was unable to connect with this error:

mcu 'mcu': Unable to connect

Once the underlying issue is corrected, use the

"FIRMWARE_RESTART" command to reset the firmware, reload the

config, and restart the host software.

Error configuring printer

Before anyone mentions changing the "mcu" it is like this:

[mcu]

serial: /dev/serial/by-id/usb-Klipper_lpc1769_11C0000C0019D895EAF47262C12000F5-if00

lsusb does not show any 3d printer on the USB ports neither does ls /dev/serial/by-id/*

Tried testing it with marlin and it also did not fix the problem.

I think the USB port is dead, but I posted this in case it's a rare issue that looks like a hardware problem.

Hardware:

SKR 1.4 Turbo on Ender 3 Pro

RPI4 with Raspbian Lite (Debian)

USB communication

I wonder who's that was on the company.

I got today a U2C board and a ebb36 gen 2 direct from BTT.

Now both are killed.

I used the cable that was with the ebb36 that has the same connector like the u2c and is compatible.

But someone very intelligent st BTT thought it's very good to rotate the pinout for that port at 180 degree.

Now 24v goes straight through the can lines.

Super idea and the port shows with it locking how it schould be insert.

No warning or hint that the pinout is switched

Hi everyone. I have a small question about the use of the board. I'm currently assembling the A4T head and plan to use the EBB 36 G2 for it. The printer has BTT Octopus Pro and then Fysetc hexa distro fusion is connected via CAN. The print head must be connected through it. And actually the question itself: can I use the EBB 36 G2 directly or do I need to connect it via an adapter board, which is included?

I put an e3v3.0 board and a 3.0.1 screen in my ender 5 plus. And I can't find firmware. I found 1 through dremc that wouldn't register the printer so I flashed the screen witch was apparently supposed to fix it (didn't work) . Then I grabbed firmware through the big tree tech's github page but they were all for normal e5's or an e5 pro and I haven't managed to successfully fix the dimensions I tried compiling my own and got sick of trial and error after it not working correctly like 5 times if anyone has the firmware or knows how to fix the dementions please let me know if been trying to figure it out with Claude and chat gpt and haven't gotten anywhere