Bigtreetech TFT24 – First Impressions

The Bigtreetech TFT24 is a mix of both display types, so once and for all you can have a touchscreen interface without sacrificing functionality. See below for our first impressions of it. For years, the RepRap Discount Full Graphics Smart Controller, and all of its derivatives have been the only way to have complete access to all of you’re machine’s settings and functionality out of the box. Many users have been drawn to the more colorful and aesthetically more pleasing interface of the touchscreens. One of the most popular ones being the MKS TFT series. We will draw comparisons to that here.

Current Screens

The problem with the prior generation of touchscreens, such as the MKS TFT, has been that they are simply serial streaming devices. They run their own firmware and do not follow the features installed on you’re 3D printer. In the Gcode blocking scenarios, such as M600 filament change, they are unable to control the printer at all.

This has led to many running the filament run-out from the touchscreen, which is less than optimal as the steppers are not locked for an extended period of time and the cooling / reheating cycles are not present. Another issue is temperature adjustments.

If you accidentally set a wrong temperature with M109, on a Gcode streamer, you cannot adjust that temperature until its stable as it will not accept another command. On a full graphics display, however, you can modify the set point behind the wait statement.

Marlin 2.0

Quite some development has been made in Marlin 2.0 to improve the host relationships. Host Prompt Support, which has support from Octoprint and Reptier). ExtUI, developed primarily by Marcio at Lulzbot, which is an API for touchscreens to have direct access to Marlin internals in a standards-compliant way. To date the only machine in the wild utilising these features is the Lulzbot Taz Pro.

The Maylan LCD and DWIN_OS have also been ported to this framework by the Marlin team. The Tiny Machines 3D branches of Creality CR10SPro and CR-X firmware has been ported to it and is in beta testing Edit : First version has been released! The issue is this requires the screen firmware be written in methods supporting this, and the printer firmware must be compiled with the specific support for the screen implementation.

Dual-Mode Display

So now we have the dual-mode display from Bigtreetech. It requires wiring in both the serial interface and the EXP1/2 headers from the Reprap Discount Full Graphics Smart Controller, referred to as a 12864 display for brevity. Out of the box, it is in 12864 mode and the firmware ships with only support this mode.

There is an update on the Bigtreetech website, which allows switching between modes. This is currently done by holding the menu button in for 5 seconds. The firmware flash is quick and painless, simply copying files to the SD card and turn it on with the card in.

My concern with the selected method is that some functions in Marlin, such as aborting the UBL manual mesh screens, require a 10-second hold. I would have preferred to see something on the touchscreen, such as holding the top and bottom left corner of the screen for 5-seconds to switch modes.

Simulation Mode

The simulator display is letter-boxed, as the aspect ratio is slightly different. They currently have a simulation mode text string displayed at the top of the screen. I would prefer to have seen this space utilized in a more practical way. The simulation mode screens are very crisp and clear and feel more responsive than even the original 12864 displays. This mode functions very well, and I have not had a single issue with it at this point.

BTT TFT24 SPI Menu

The touchscreen mode appears very similar to the MKS at first; however, several things jump out very quickly. First off, in the settings menu, you can adjust the baud rate without needing to reconnect. It only allows switching between 115200 and 250000 baud. However, as these are the most common outside of Ultimaker this should suffice for most users. There is also a disconnect button which may prevent some of the host collisions. Especially during firmware flash, that is an issue which plagued the MKS TFT’s. We have had many reports of users having issues flashing firmware updates on the Evnovo / Sidewinder Artillery X1 Due to this.

The Downsides

No product is perfect, one thing that I was slightly disappointed with was that the footprint doesn’t line up as a drop-in for MKS TFT 2.4. So it makes it harder to install as a drop-in for anything. It would also be nice to have a remote screen adapter so it could be made to drop in for either a 12864 or mks and set the button / USB / sd card elsewhere.

As with many other LCD’s by Bigtreetech, the connectors are flipped. The pins, are an L soldered type underneath, not a through the pin. This makes removing the plastic housing to flip it a risky endeavor. Also, the PCB is not etched with the first tab direction, so it is easy to forget which way it needs to go. On other issue is that the screen is not solidly connected to its backlight. This means you’re mounting adapter needs to hold the border of the screen very well. Or it will move as you try to use the touch interface.

With some of the items above being software, this becomes quite an important point. The firmware is up on GitHub with a platformIO project configuration. If you have any experience compiling Marlin 2.0, you should already be familiar with this in VSCode. The source code is open and available for you to modify to suit your needs!

This is a first in one of these touchscreen products and has been a long-standing sore spot. On the MKS displays as functionality has been so limited over time, there has been a push for the software to be opened. Many users have been posting feature requests and bug reports on the MKS GitHub repository. They have not been responded to in some time, so it appears Makerbase has abandoned it. The repository only hosts binary files however so there is no hope for for further improvement. The Image files are also standard formats instead of the binary files the MKS TFT requires.

Conclusions

Overall this is quite a good product and with the 3.5in version now shipping, something I can see replacing many screens in the near future. I can’t see any reason for anyone to buy another MKS TFT, given the past history with GPL compliance, similar price points and enhanced functionality found here. While this is slightly more expensive than a similarly sized 12864 LCD, the added feature is well worth the cost difference.

Where Buy

Bigtreetech TFT24 V1.1 graphic smart display controller board. The larger 3.5in version is  available also here!

Here is another first impression review of the Anet E16 3D Printer.

David Menzel

Active contributor to the Marlin project with over 100 commits and counting. Printing service provider with nearly 30 machines specializing in industrial components materials. Industrial automation controls engineer with over 10 years of experience in automation.