Custom PCB with a 1.14” display is not working

Using Arduino Displays
1

Hello
I made a little PCB with a display, a rotary encoder and the Waveshare rp2040 zero (I use a breakoutboard, because I didn't want to design a whole microcontroller on the PCB).

The display is a 1.14” TFT display that I bought from AliExpress (link to product on AliExpress).
The rotary encoder is functioning, but the display isn't.
The schematic for the display I copied from Waveshare's 1,14” LCD Module (link to schematic from Waveshare).
According to the seller's data sheet, the display has an operating voltage of 3.3V.
On the rp2040 zero SCL is pin 2 and MISO / DIN is pin 3.

Here is the schematic / PCB that I made in KiCad:

Bildschirmfoto 2024-07-07 um 22.48.12
Bildschirmfoto 2024-07-07 um 22.48.121998×921 73.9 KB

Bildschirmfoto 2024-07-07 um 22.50.40
Bildschirmfoto 2024-07-07 um 22.50.402171×984 239 KB

For the testing the display, I modified the example “graphictest” from the Adafruit ST7735 and ST7789 Library so that the test suits the display type.

The changed definitions:

#define TFT_CS 5
#define TFT_RST 7  // Or set to -1 and connect to Arduino RESET pin
#define TFT_DC 6

The modified object instance:

// For 1.14", 1.3", 1.54", 1.69", and 2.0" TFT with ST7789:
Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST);

The changed initializer:

  // OR use this initializer (uncomment) if using a 1.14" 240x135 TFT:
  tft.init(135, 240);  // Init ST7789 240x135

I measured the supply voltage for the display, looked twice to see if the resistors were in the right position, and measured if there was any contact between the pins from the display cable.
I don't think I damaged the display while soldering it on because I used a lot of flux and worked quickly.

Did I make the PCB wrong or is it the software?

Now I'm just in the dark and can't find the error. Please take a look and help me bring the display to life.
Thanks in advance :slight_smile:

1 Like
2

Welcome to the forum

Did you test the circuit on a breadboard before committing to the PCB ?

3

Yes and no. I tested it before with a 0.96” display module from Waveshare, but then I wanted a slightly larger display. The only difference between the 0.96” and 1.14” displays is the driver, but the resistors, capacitors, and transistors are the same on both displays. I don't think it's a big difference (or is it?) since the library can drive both drivers and the schematic is the same.
Since I wanted to save money on another display that is practically the same, I went straight to the PCB.