Seeeduino XIAO SAMD21 tft ST7789

Products & Technology XIAO
1

Good morning everyone, I ask for your help, I have a seeeduino xiao samd21 and I wanted to connect a ST7789 display and make it go with the eSPI tft library, do you think it is possible and if so how do you recommend me to do it, because I have not found any indication around
help me please, thanks

i made this sketch to try but i just get black screen

#include <Adafruit_GFX.h>
#include <Adafruit_ST7789.h>
#include <SPI.h>

//#define TFT_CS 0
#define TFT_DC 4
#define TFT_RST 5
#define TFT_MOSI 10
#define TFT_SCLK 8

Adafruit_ST7789 tft = Adafruit_ST7789(TFT_DC, TFT_MOSI, TFT_SCLK, TFT_RST);

void setup(void)  {

Serial.begin(115200);
tft.init(240, 240, SPI_MODE3); // or tft.init(320, 240, SPI_MODE3);

tft.setRotation(2);
tft.fillScreen(ST77XX_BLACK);
delay(4000);

}

void loop() {
// put your main code here, to run repeatedly:
tft.setTextWrap(false);
tft.fillScreen(ST77XX_BLACK);
tft.setCursor(0, 30);
tft.setTextColor(ST77XX_RED);
tft.setTextSize(1);
tft.print("HELLO WORLD");
tft.setTextColor(ST77XX_YELLOW);
tft.setTextSize(2);
tft.print("HELLO WORLD");
}
2

Try putting a delay at end of your loop() function - it is continuously looping around and you may be seeing the black fill preferentially,

3

Try the code below. I checked it on “ST7735”, so maybe it will not work correctly on “ST7789”.

#include <Adafruit_GFX.h>
#include <Adafruit_ST7789.h>
#include <SPI.h>

#define TFT_CS A0
#define TFT_DC A4
#define TFT_RST A5
//#define TFT_MOSI A10
//#define TFT_SCLK A8

//Adafruit_ST7789 tft = Adafruit_ST7789(TFT_DC, TFT_MOSI, TFT_SCLK, TFT_RST);
Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST);

void setup(void)  {
//  Serial.begin(115200);
//  tft.init(240, 240, SPI_MODE3); // or tft.init(320, 240, SPI_MODE3);
  tft.init(240, 240);

//  tft.setRotation(2);
  tft.setRotation(3);
  tft.fillScreen(ST77XX_BLACK);
//  delay(4000);
}

void loop() {
//  tft.setTextWrap(false);
  tft.setTextWrap(true);
  tft.fillScreen(ST77XX_BLACK);
  tft.setCursor(0, 30);
  tft.setTextColor(ST77XX_RED);
  tft.setTextSize(1);
//  tft.print("HELLO WORLD");
  tft.println("HELLO WORLD");
  tft.setTextColor(ST77XX_YELLOW);
  tft.setTextSize(2);
//  tft.print("HELLO WORLD");
  tft.println("HELLO WORLD");
}
4

tried it doesn’t work always black screen

5

Here is a snippet from the Adafruit_ST7789.h file with public functions:

/// Subclass of ST77XX type display for ST7789 TFT Driver
class Adafruit_ST7789 : public Adafruit_ST77xx {
public:
  Adafruit_ST7789(int8_t cs, int8_t dc, int8_t mosi, int8_t sclk,
                  int8_t rst = -1);
  Adafruit_ST7789(int8_t cs, int8_t dc, int8_t rst);
#if !defined(ESP8266)
  Adafruit_ST7789(SPIClass *spiClass, int8_t cs, int8_t dc, int8_t rst);
#endif // end !ESP8266

  void setRotation(uint8_t m);
  void init(uint16_t width, uint16_t height, uint8_t spiMode = SPI_MODE0);

Note that the first parameter is CS, not DC as in the first code segment.

So that means the original;

Adafruit_ST7789 tft = Adafruit_ST7789(TFT_DC, TFT_MOSI, TFT_SCLK, TFT_RST);

would set in the arduino module:

cs = TFT_DC     ;   //okay, arbitrary pin
dc = TFT_MOSI   ;   //not so good SPI MOSI/data (10) on XIAO not control pin
mosi = TFT_SCLK ;   //again not so good. XIAO SPI SCLK (8) not data source 
sclk = TFT_RST  ;   //again not so good, set to discrete pin no clock
rst = -1;           //not passed, default okay
6

Hi Lidas,
Is the connection correct?
A0 ---- CS
A4 ---- DC
A5 ---- RES
A10 — SDA
A8 ---- SCL
Please try copy-paste the code below.

#include <Adafruit_GFX.h>
#include <Adafruit_ST7789.h>
#include <SPI.h>

#define TFT_CS A0       // A0 ---- CS
#define TFT_DC A4       // A4 ---- DC
#define TFT_RST A5      // A5 ---- RES
//#define TFT_MOSI A10  // A10 --- SDA
//#define TFT_SCLK A8   // A8 ---- SCL

Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST);

void setup(void)  {
  tft.init(240, 240);
  tft.setRotation(3);
  tft.fillScreen(ST77XX_BLACK);
}

void loop() {
  tft.setTextWrap(true);
  tft.fillScreen(ST77XX_WHITE);
//  tft.fillScreen(ST77XX_BLACK);
  tft.setCursor(0, 30);
  tft.setTextColor(ST77XX_RED);
  tft.setTextSize(1);
  tft.println("HELLO WORLD");
  tft.setTextColor(ST77XX_YELLOW);
  tft.setTextSize(2);
  tft.println("HELLO WORLD");
  delay(1000);
}