OctoPrint with TFT35 and SKR Mini V2

What is the problem?

I have an Ender 3 Pro with SKR Mini v2 and have been running Marlin fine for more than a year.

Recently bought a TFT 35 and since that’s connected OctoPrint does not want to work.

I use OctoPrint on a laptop and it was fine until the TFT.

What did you already try to solve it?

Updated Marlin found some info on the Serial Ports which I did, tried another USB cable, disconnected the TFT but it is still not connecting.

Have you tried running in safe mode?


Did running in safe mode solve the problem?


Systeminfo Bundle

You can download this in OctoPrint's System Information dialog ... no bundle, no support!)
octoprint-systeminfo-20221229145248.zip (58.7 KB)

Additional information about your setup

OctoPrint version, OctoPi version, printer, firmware, browser, operating system, ... as much data as possible

OctoPrint version: 1.8.6
Printer: Ender 3 Pro
Board: SKR Mini V2
Firmware: Marlin 2.1.2
Browser: Chrome
OS: Windows 10

When you setup the TFT did you enable a second serial port in Marlin (ie. SERIAL_PORT_2) or did you just change the value of SERIAL_PORT?

If you didn't enable the second serial port then you probably disabled the serial port access to the USB port.

Thanks for the reply, I have enabled a second one and it's now set in configuration.h though only the TFT is working OctoPrint doesn't want to connect.

#define SERIAL_PORT 1
#define BAUDRATE 115200

#define SERIAL_PORT_2 2
#define BAUDRATE_2 115200

You still have to use the correct values for serial ports.

As indicated by the comment right above the setting, one of them needs to be -1 in order to have a serial connection on the USB port:

 * Select the serial port on the board to use for communication with the host.
 * This allows the connection of wireless adapters (for instance) to non-default port pins.
 * Serial port -1 is the USB emulated serial port, if available.
 * Note: The first serial port (-1 or 0) will always be used by the Arduino bootloader.
 * :[-1, 0, 1, 2, 3, 4, 5, 6, 7]

So, you should set one to -1 and the other to 2.

It's also worth noting that the other serial port number greater than 0 correspond to physical serial ports on the mcu. For BTT boards, you can usually determine where those are wired to by looking at the pin diagrams. Any RXn and TXn pins are serial port n. For example, the TFT is indeed serial port 2 in your case:

(from BIGTREETECH-SKR-mini-E3/BTT SKR MINI E3 V2.0-PIN.pdf at 36cbce5e0444c7a1071df45dd2f04c94f58c4148 · bigtreetech/BIGTREETECH-SKR-mini-E3 · GitHub )

Thanks I got it working.

Appreciate your input.

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