Need help with ST7789 display

Other Hardware Displays
1

Hello all,

I have a 1.54" IPS 240x240 TFT display. Please see the attached images. I use a 8266 D1 mini and my wiring is:

SCL --- D5
SDA --- D7
RES --- D2
DC --- D3

but this probably is wrong (got it from the net).

The code I use to test is the example program of Adafruit, ST7789 Library -> graphicstest. The changes I made to the source are that I use the following ST7789 lines instead of the ST7735 lines:

// For 1.14", 1.3", 1.54", and 2.0" TFT with ST7789:
Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST);

and

// OR use this initializer (uncomment) if using a 1.3" or 1.54" 240x240 TFT:
tft.init(240, 240); // Init ST7789 240x240

What am I doing wrong? I cannot figure out and hope that someone can help.

Thank you,
Karl

240x240.jpg
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Setup.jpg
Setup.jpg1920×1281 395 KB

240x240.jpg
240x240.jpg1413×1920 391 KB

Setup.jpg
Setup.jpg1920×1281 395 KB

2

From your photos TFT_CS looks as if connected to D4 pin.
But your text does not mention any define.

Life is easier if you quote your actual constructor statement. e.g.

// For 1.14", 1.3", 1.54", and 2.0" TFT with ST7789:
//Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST);
Adafruit_ST7789 tft = Adafruit_ST7789(D4, D3, D2);
3

Thank you for your reply! I tried your suggestion and it works. I did not have connected CS at all.

So, I think I'm all set then....

Karl

4

What is the BLK pin used for? Just curious.

Karl

5

Backlight. Either leave as no connection or attach to a GPIO pin.

6

Thank you. So I could switch backlight off by setting BLK to HIGH?

Karl

7

I suspect that the BLK pin is active-high. i.e. connect HIGH to switch backlight on.

It is simple enough to try.

  1. connect BLK to 3.3V. does it light?
  2. no connection. does it light ?
  3. connect BLK to GND. does it light ?

David.

8

Did as youn said. Connecting BLK to GND switches the light off.

Thx,
Karl

9

If you said that "1. connect BLK to 3.3V. does it light?" was YES.

And "3. connect BLK to GND. does it light ?" was NO

that means BLK is active-high. (and I suspect that n.c. is YES too)

10

Exactly as you say.

Karl

11

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