SKR 1.2 + TFT - Marlin works but Touchscreen = 'no printer attached

Installed firmware on both board and TFT. I can long press the knob and switch between the two modes. Marlin works - I have control over all axis and can verify movement is normal. Touchscreen mode reads ‘no printer attached’.

I’ve read through the posts here and tried to change baud to 250000 w/ no luck. Also tried a variety of connections with the gray cables omitted and the black TFT cable omitted. The numbers on this pic in the instructions are super confusing. But, I imagine that if marlin works via the knob, the gray cables are setup properly, rt?

I think when I first set it up I had the black TFT cable plugged in upside down on the board. Could I have fried the touch connection?

I don’t mind using the marlin interface - would I be losing any functionality by doing this and avoiding the touch interface?

Thanks -


Your serial cable looks to be placed right. Reversing the cable does not do any damage (guess how I know that). So it must be a firmware or speed thing. Which firmware (mainboard) do you use?

Try setting
#define SERIAL_PORT -1
#define SERIAL_PORT_2 0 or
#define SERIAL_PORT_2 1

Thanks for the quick reply - I downloaded and flashed the non-end stop variety firmware named: V1CNC_SkrPro_2209-

Would I be making those serial adjustments in the TFT’s config.ini file?

no, in configuration.h of the SKR-firmware

Ok - I found the configuration.h file within the marlin zip file - I can open this via text editor and make the changes. Would I then need to compile a new firmware.bin file and flash it to the board?

yes, but editing can also be done in VS-code…

Ahh - ok - I don’t have a working copy of MS Visual Studio. I’ll try compiling and flashing a new build after I down some food - thanks!

Well, gave a good meal :wink: It is almost 3AM over here, so I am off to bed

That firmware is set up already for the usb and the tft connection. On the pro, it is -1,1.

The black cable is the one that connects it in the touch screen mode.

So, my configuration.h file was set to:

#define SERIAL_PORT 1
#define SERIAL_PORT_2 0

You’re suggesting it should be

#define SERIAL_PORT -1
#define SERIAL_PORT_2 1

That was easy but I just went down a rabbit hole trying to build the firmware. According to these instructions, Since SKR is an arm cortex board I can’t use Arduino to compile the firmware. I walked through the downloading marlin instructions on installing via sublime text 3 and also installed Python 2.7. I believe I successfully built the autobuild menu.

When I run Auto Build > PIO Upload I just get a blank black window. Upon closing it I can see the code that ran. It includes:

FileNotFoundError: [WinError 2] The system cannot find the file specified

And it also lists python version 3.7.2 (I have an alternate build of python installed for other projects)

Am I on the right track here or is there an easier way to change 2 characters and create a bin file?

I should specify, not sure if it makes a difference - I don’t plan to use the USB port and tether to a computer - I’d just like to use the touchscreen menu if it has extra features beyond marlin. Eventually I’d like to add a gamepad/joystick for moving the machine, but from what I read I’ll need a Pi and more code.

What OS are you on?

The most easy way is to install VS-Code. I love the video’s from Chris Riley on this subject:

To test, here is a fresh build binary: (110.9 KB)


Those settings are not in the firmware Jonathan mentioned, therefore should be altered.

It is probably my memory that is wrong. The firmware in github is right.

No, I just checked. The firmware should be set to 1,-1.

Now I’m wondering if you have the wrong firmware.

It should be one of the skrpro ones from here:

MarlinBuilder releases.

Well, perhaps Jonathan can try the firmware I built. Afaik serial port 1 is reserved for something else and can not be used for the TFT screen…

check SKR PRO Serial Ports · Issue #18 · bigtreetech/BIGTREETECH-SKR-PRO-V1.1 (

From that post:

Serial port:
-1 is for USB CDC
1 is for TFT
6 is for ESP-01S

I meant the first serial port is reserved for usb connection with host end therfore should be -1.

I don’t think so. This firmware is what Ryan ships and he and I have both tested it.

If Jonathan has firmware where they are set to 0,1, then I am guessing it isn’t from marlin builder. Or maybe it is the skr1p3 version.

Very cool - I didn’t realize VS Code was a separate (and free) program apart from MS Visual Studio - I was able to download the and install it - followed Chris’s video - thanks for that Kees. I compiled and uploaded the new bin w/out issue. I can tell the new firmware took - I see a custom name for the CNC that I specified via the Marlin mode.

First I tried the -1, 1 settings for SERIAL_PORT I’m still got a 'no printer attached error). I also tried the firmware Kees compiled and that had the same result - still no printer via touch. Then I tried the 1, -1 that Jeff just suggested and still the same result.

I am using firmware found here: Marlin_V1CNC_SkrPro_2209_2.0.7.2_508-src

I just downloaded the ZIP again and opened it in a new folder - checked the configuration.h file and it does read 1, -1. I copied the firmware.bin file to the micro SD and installed it - reset the board and I still get the same ‘no printer attached’ message via touch mode.

Here’s a screenshot of my downloads folder - I believe I’m using the right files and have been since last night:

Not sure why I’d have different values for serial.

Maybe I should wipe both board and TFT and start fresh?

Did you use the right port-speed settings?