I am a newbie on this forum and I did try to search for an earlier answer to my question.
However an embarrassing long time ago, I decided to construct a 3d printer. No interest in a ready made as I just wanted a fun product. I have the electronics all built and pretty much tested and the machine frame constructed with stepper motors. Covid has returned me to my project.
I have built the key electronics around the latest 5 output Smoothieboard and It occured to me that the PoPprint TFT35 V1.2 TFT3.5 Inch Touch Screen might be nice to have as it ticks all the boxes in terms of touch button presses to move and generally control my machine. It’s also pretty cheap.
My question is that it seems to come with loads of connectors (3 actually) and I can’t work out how I connect it to the smoothiboard. Anybody done this or have any idea what pins on the board are used. Also what changes do I need to make to the config file to enable a dialogue.
Thanks for letting me join and talk to you guys.
If it’s the same as the BTT variant of which it claims to be a clone, with the two ribbon cables, it emulates the Reprap Discount GLCD when you select “Marlin” mode.
Hi, thanks for your reply. I have to say that as I am not a person who works in the 3D printer field, the terms BTT and Reprap Discount GLCD are above my head. I am willing to learn though but I’m not sure how to select the Marlin mode. My board came with configuration and firmware files on a micro sd card and I have read through them carefully and they seem to be OK when the board is loaded with them. I can use the general commands from Pronterface with that. I get that Marlin software is based around Arduino but it doesn’t seem to help with installation of a touch screen on a smoothieboard.
The PoPprint listing I found on amazon.co.uk said it was a clone of the BigTreeTech (“BTT”) device.
On the BTT devices, you long-touch the screen to put it in “Marlin mode” which means, as I understand it, that it emulates a Reprap Discount GLCD device.
The URL I gave you talks about how to configure Smoothie for Reprap Discount GLCD displays among others.
Since I don’t have that particular device (I have a similar BTT device) and don’t have a smoothieboard, I’ll step out of the way now. 
Thanks anyway for that, it’s a start.
If you just want to use the touch interface, all you need to hook up is five volts, ground, TX and RX. That will let the touchscreen act as a serial device and host sending all of the commands remotely just like if you were sending it from a computer. The Marlin mode is actually a software 12864 emulation mode. It might work with smoothie to display the characters that smoothie would normally display on a full graphics display, I am not sure how the emulation portion functions. But to be honest I’d probably just stick with the touchscreen mode it’s pretty functional and even has a g code sending console which is handy for sending manual commands. The SD card / Usb isn’t accessible in the “Marlin emulation mode”.
On a side note to switch modes you long press the button not the touch screen.
At least on the E3 version I have, I have been able to long-press the screen. Maybe both work? I think it shares most of its firmware with the version that has no knob at all.
Good to know, I didn’t know long touch worked for touch versions. You would need to manually add a knob added to navigate Marlin mode right?
All I know of the knobless version I know from following @Brook_Drumm on twitter, since he was posting about using it on the resurrected printrbot. Swipe gestures maybe? 
Thanks guys. I think I have gleaned enough from you all to bite the bullet and get one of the screens to add on to the kit and I won’t be chucking £50 down the drain. At least I understand that it will work even if I have to fiddle around with things to get the right look to the touch screen. It seems from what I have gathered, is that the Tft has a screen which will support modified styles of buttons on its GUI and I believe will also support Gcode files. These can all be programmed into an an onboard sd card I believe.
I will leave the thread open for now in case anyone wants to add. But once again thanks
Note that for the GUI buttons and gcode files on the onboard SD card you need to do it the way @Eclsnowman suggested where you are using the graphical screen as a serial terminal. You can’t use it in “marlin mode” where you connect it with both the large 10-pin ribbon cables.
I guess that Marlin is an on board software. As I am using a Smoothieboard then that would not be something I would use as Smoothie has its own software config file. The board doesn’t appear to have plug connections for the two ribbon cables but there is a serial connector (4 pin) available so I am assuming that would be the only connection between the board and the TFT35 if I understand what @Eclsnowman has said.
Marlin is a different controller firmware primarily for 3d printing. What the TFT35 documentation and user interface refer to as Marlin mode actually isn’t specific to Marlin; rather, it is an emulation of a “12864” controller, which for smoothie you would use the smoothieware Reprap Discount GLCD configuration.
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If you use “Marlin mode” on that display to control your smoothieboard, you use both 10-conductor ribbon cables and can’t use the SD card on the display, and you follow the Smoothieware documentation for a “Reprap Discount GLCD” panel.
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If you use “Touch mode” on that display to control your smoothieboard you need to provide it with four connections. There is a 5-connector ribbon cable that may serve this purpose. I believe that you just connect it to the UART port.
All this assumes that this board is a faithful clone of the BTT board.
I think that the solution was hiding in the smoothieboard documentation and although on first read it looks a bit of an uphill technical struggle, it looks like everything is there, So thanks to all.
Here’s the link for anyone interested.
http://smoothieware.org/smoopi