Cant get ST7735 display working with Teensy 4.1

[Salchicha]

I have an ST7735 (from A-ZDelivery) and a Teensy 4.1, whatever I do I just can get the screen to even come on at all, its connected up as follows:

LED > 36
SCK > 13
SDA > 11
A0 > 33
RESET > 7
CS > 2
GROUND > GROUND
VCC > 5V

#include <Adafruit_GFX.h>    // Include the Adafruit GFX Library
#include <Adafruit_ST7735.h> // Include the Adafruit ST7735 Library
#include <SPI.h>

#define mosi      11
#define TFT_CS    2
#define TFT_RST   7
#define TFT_DC    33
#define TFT_SCLK  13
#define BACKLIGHT_PIN 36

//Adafruit_ST7735 tft = Adafruit_ST7735(TFT_CS, TFT_DC, TFT_RST, TFT_SCLK);
Adafruit_ST7735 tft = Adafruit_ST7735(TFT_CS, TFT_DC, TFT_RST);
void setup() {

Serial.begin(9600);
Serial.print(F("init 1.8 tft screen"));
tft.initR(INITR_GREENTAB); // Init ST7735S chip, black tab
Serial.println(F("Initialized"));
tft.fillScreen(ST77XX_BLACK);
drawtext("Hello! from \n AZ-delivery", ST77XX_RED);
delay(1000);
fillScreenBlink(ST77XX_WHITE, ST77XX_RED);
delay(500);
Serial.println("done");
delay(1000);

}

void loop() {

 Serial.print("Running....");
Serial.print("\n");

tft.invertDisplay(true);
delay(500);
tft.invertDisplay(false);
delay(500);

}

void drawtext(char *text, uint16_t color) {

tft.setCursor(0, 50);
tft.setTextColor(color);
tft.setTextSize(2);
tft.setTextWrap(true);
tft.print(text);
}
void fillScreenBlink(uint16_t color1, uint16_t color2) {
tft.fillScreen(color1);
delay(1000);
tft.fillScreen(color2);
}

 

[rjenkinsgb]

Try adding

Wire.begin();

to the start of the setup section (prior to any display init), to initialise the SPI port?

 

[ZipZapOuch]

Try adding

Wire.begin();

to the start of the setup section (prior to any display init), to initialise the SPI port?

I think that's to initialize I2C. I think he needs
SPI.begin()

 

[Salchicha]

I think that's to initialize I2C. I think he needs
SPI.begin()

Tried both and still nothing.....is it supposed to show so some sort of life when connected to power even with no/incorrect code?
Is there a way I can test it's not a dud, with a multimeter or something?

 

[Nigel Goodwin]

Tried both and still nothing.....is it supposed to show so some sort of life when connected to power even with no/incorrect code?

No, it's completely dead until it's initialised by the processor.

Assuming the code is correct and working, then the usual problems are wrong SPI connections, or wrong SPI settings.

If the backlight lighting up?.

This website here:

Testing the ILI9341 TFT LCD with Teensy | Details | Hackaday.io

<p>I'm still waiting for the last few components to arrive before I can build the controller, however one thing I wanted to do first is test my chosen LCD with the Teensy microcontroller. I've never used a TFT LCD with Arduino or Teensy before, so I first wanted to make sure that I could get the...

hackaday.io

Suggests various alternatives for CS and D/C, none of which are pin 2 or pin 33 - are thos pins perhaps used by the Teensy?

 

[Ian Rogers]

I was looking at the TFT_SCK definition.. Although its not needed the mosi definition will be for Arduino not teensy. you may have to specify them differently Pin 13 is the builtin LED maybe move the SPI to SPI1
I seem to remember the Teensy JSON has a pin map to make it usable.
Try not defining any pin other than CS, DC and RST just in case its wobbling the library.

 

[Salchicha]

Thanks all, is now working, I wired it up the same way as that Hackaday article (using the 4.1 equivalent pins). Is now configured like this:

LED > VCC 5V
SCK > 13
SDA > 11
A0 (DC) > 15
RESET > 3.3v
CS > 10
GROUND > GROUND
VCC > VCC 5V