0

2.8" TFT Questions (ID 1774)
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

2.8" TFT Questions (ID 1774)

by fergusondavid6 on Sat Feb 04, 2017 9:20 pm

I'm interested in using the 2.8" TFT Display with Resistive Touchscreencreen in an application that requires the thickness to be as minimal as possible. Therefore I would be looking at the display without the breakout board, to save space.

However, I don't need the touchscreen for what I want to do with it, and as far as I'm concerned, it's just taking up more space. So I'm wondering if it can be removed from the display (and I don't mind if I have to damage the touch panel to remove it - I won't be needing it after).

And as I wouldn't have the breakout board, I was just wanting to check that these are the connections I'd wire up to a 3.3v arduino to get this display working (taken from the tft resistive touch schematic):

Code: Select all | TOGGLE FULL SIZE
pin
1      ->   GND
2      ->   10ohm resistor   ->   3.3v
3      ->   10ohm resistor   ->   3.3v
4      ->   10ohm resistor   ->   3.3v
5      ->   10ohm resistor   ->   3.3v
6
7      ->   3.3v
8      ->   3.3v
9      ->   3.3v
10
11
...
32
33      ->   arduino MISO
34      ->   arduino MOSI
35      ->   GND
36      ->   arduino D/C select
37      ->   arduino CLK
38      ->   arduino CS
39
40      ->   3.3v
41      ->   3.3v
42      ->   3.3v
43      ->   GND
44
45
46
47
48      ->   GND
49      ->   GND
50      ->   GND


Thanks in advance

fergusondavid6
 
Posts: 3
Joined: Sat Feb 04, 2017 5:07 pm

Re: 2.8" TFT Questions (ID 1774)

by mlepage on Tue Oct 24, 2017 12:22 am

After a lot of reading of the data sheet and tutorials, that's my understanding of what to hook up.

I'm using product 1774 with a Raspberry Pi, 3.3V. I have the SPI driver (fbtft) loading and it looks to be configured correctly (according to dmesg) but I still see only white screen.

I will keep trying.

mlepage
 
Posts: 5
Joined: Sun Oct 22, 2017 2:05 pm

Re: 2.8" TFT Questions (ID 1774)

by fergusondavid6 on Tue Oct 24, 2017 4:11 am

Ah sorry, I solved this but didn't update it here.

There's a mistake in the data sheet! It's been a few months now so I can't exactly remember where and with what, but you have to tie one or two extra wires to gnd/vcc and then it starts working.

To work it out, I looked at the PiTFT schematic instead of the breakout board TFT schematic. Just taking a very quick glance now shows that it might be with lines 6,7,8,9 from the LCD - in the PiTFT they have 6 to gnd and the rest to vcc. You might want to try that.

Edit: I've just looked at pictures of how I wired the display (don't have access to the actual display at the moment) and yes, I've wired 6 to GND and 7,8,9 to VCC. I'm now reasonably confident that was what was causing the issue, and when I wired it like that it worked.
Try that out, and if you get it working please update it here!

fergusondavid6
 
Posts: 3
Joined: Sat Feb 04, 2017 5:07 pm

Re: 2.8" TFT Questions (ID 1774)

by mlepage on Thu Feb 08, 2018 11:57 pm

Hi, I was just getting back to this TFT, great to have more info.

If you mean lines 6,7,8,9 from the ribbon cable (and note that the breakout board has the labels backward so it's 45,44,43,42 on that), then having 6 low and 7,8,9 hi means 4 wire mode. (If all are low, it's 8-bit mode).

I tried it, still no luck, but I have to go over the datasheets and all my wiring again. I do notice maybe my power or ribbon is flakey, as if I move it, the backlight changes, but I just get white. Linux dmesg at boot says stuff about stmpe (the older PiTFT) failing (I find my old 3.5" LCD does work though), but it then goes on about ILI9341 (which this one has) succeeding with fb1 framebuffer. So I'm pretty sure the software is correctly configured, and I'm just not getting some of the wiring correct.

I'll keep trying and post back when I get it working. I also got a 1770 TFT with the added PCB to try, so I can compare (and also swap panels if I get it working, to rule that out).

mlepage
 
Posts: 5
Joined: Sun Oct 22, 2017 2:05 pm

Re: 2.8" TFT Questions (ID 1774)

by mlepage on Sat Feb 10, 2018 6:42 pm

OK, I hooked up my Product 1770 (display + breakout) in SPI (4-wire) mode and it works fine. Using Raspberry Pi, /boot/config.txt dtoverlay line with pitft28-resistive, I can get 20 fps on the fbtft driver. So the software is good.

When I use Product 1774 (raw display) with just the breakout/connector (products 1492 and 1773), same software and configuration, it sometimes boots to show graphics, but mostly remains white at boot. And even if it shows graphics, it's usually for only under 30s then it goes white.

I haven't swapped display panels or anything yet, but at this point I'm wondering, if I need some resistors or something. EDIT: I swapped panels, the bare panel (1774) does work fine in the complete breakout (1770). So there's something in the complete breakout that seems to be missing (and necessary) to get the bare display working.

mlepage
 
Posts: 5
Joined: Sun Oct 22, 2017 2:05 pm

Re: 2.8" TFT Questions (ID 1774)

by mlepage on Sat Feb 10, 2018 9:50 pm

Reading more data sheets and schematics, I added a 10uF and two 0.1uF capacitors across the power rails, still no go.

I could use the 1770 complete breakout board display, as it works, but I'd really like to get the 1774 bare display working, as it's much thinner and lighter.

mlepage
 
Posts: 5
Joined: Sun Oct 22, 2017 2:05 pm

Please be positive and constructive with your questions and comments.