We've got libraries for using the TFT in Arduino, so its easy to get drawing!
Install Libraries
From the previous page, don't forget to install all those libraries!
Setup
Make sure you've got the Hallowing M0 selected as the board type, and the correct port as well
Now load up the example at the bottom of this page in a Arduino sketch. Its an adaptation of our standard graphics test, but you'll note we add some lines that are specific to the Hallowing.
First, these are the pins that are connected:
// These are 'hard wired' #define TFT_CS 39 #define TFT_RST 37 #define TFT_DC 38 #define TFT_BACKLIGHT 7
In setup() don't forget to turn the backlight on!
void setup(void) {
pinMode(TFT_BACKLIGHT, OUTPUT);
digitalWrite(TFT_BACKLIGHT, HIGH);
You can dim the backlight with analogWrite(TFT_BACKLIGHT, brightness) where brightess is between 0 (off) and 255 (full on)
Also, rotate the display:
tft.setRotation(2);
Once you have it all working, you can visit the Adafruit GFX library guide page to learn more about all the different shapes you can draw!
/**************************************************************************
This is a library for several Adafruit displays based on ST77* drivers.
Works with the HalloWing M0 Express
----> http://www.adafruit.com/products/3900
Check out the links above for our tutorials and wiring diagrams.
Adafruit invests time and resources providing this open source code,
please support Adafruit and open-source hardware by purchasing
products from Adafruit!
Written by Limor Fried/Ladyada for Adafruit Industries.
MIT license, all text above must be included in any redistribution
**************************************************************************/
#include <Adafruit_GFX.h> // Core graphics library
#include <Adafruit_ST7735.h> // Hardware-specific library for ST7735
#include <SPI.h>
#define TFT_CS 39 // Hallowing display control pins: chip select
#define TFT_RST 37 // Display reset
#define TFT_DC 38 // Display data/command select
#define TFT_BACKLIGHT 7 // Display backlight pin
// OPTION 1 (recommended) is to use the HARDWARE SPI pins, which are unique
// to each board and not reassignable.
Adafruit_ST7735 tft = Adafruit_ST7735(TFT_CS, TFT_DC, TFT_RST);
// OPTION 2 lets you interface the display using ANY TWO or THREE PINS,
// tradeoff being that performance is not as fast as hardware SPI above.
//#define TFT_MOSI 29 // Data out
//#define TFT_SCLK 30 // Clock out
//Adafruit_ST7735 tft = Adafruit_ST7735(TFT_CS, TFT_DC, TFT_MOSI, TFT_SCLK, TFT_RST);
float p = 3.1415926;
void setup(void) {
Serial.begin(9600);
Serial.print(F("Hello! HalloWing TFT Test"));
pinMode(TFT_BACKLIGHT, OUTPUT);
digitalWrite(TFT_BACKLIGHT, HIGH); // Backlight on
tft.initR(INITR_HALLOWING); // Initialize HalloWing-oriented screen
Serial.println(F("Initialized"));
uint16_t time = millis();
tft.fillScreen(ST77XX_BLACK);
time = millis() - time;
Serial.println(time, DEC);
delay(500);
// large block of text
tft.fillScreen(ST77XX_BLACK);
testdrawtext("Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur adipiscing ante sed nibh tincidunt feugiat. Maecenas enim massa, fringilla sed malesuada et, malesuada sit amet turpis. Sed porttitor neque ut ante pretium vitae malesuada nunc bibendum. Nullam aliquet ultrices massa eu hendrerit. Ut sed nisi lorem. In vestibulum purus a tortor imperdiet posuere. ", ST77XX_WHITE);
delay(1000);
// tft print function!
tftPrintTest();
delay(4000);
// a single pixel
tft.drawPixel(tft.width()/2, tft.height()/2, ST77XX_GREEN);
delay(500);
// line draw test
testlines(ST77XX_YELLOW);
delay(500);
// optimized lines
testfastlines(ST77XX_RED, ST77XX_BLUE);
delay(500);
testdrawrects(ST77XX_GREEN);
delay(500);
testfillrects(ST77XX_YELLOW, ST77XX_MAGENTA);
delay(500);
tft.fillScreen(ST77XX_BLACK);
testfillcircles(10, ST77XX_BLUE);
testdrawcircles(10, ST77XX_WHITE);
delay(500);
testroundrects();
delay(500);
testtriangles();
delay(500);
mediabuttons();
delay(500);
Serial.println("done");
delay(1000);
}
void loop() {
tft.invertDisplay(true);
delay(500);
tft.invertDisplay(false);
delay(500);
}
void testlines(uint16_t color) {
tft.fillScreen(ST77XX_BLACK);
for (int16_t x=0; x < tft.width(); x+=6) {
tft.drawLine(0, 0, x, tft.height()-1, color);
delay(0);
}
for (int16_t y=0; y < tft.height(); y+=6) {
tft.drawLine(0, 0, tft.width()-1, y, color);
delay(0);
}
tft.fillScreen(ST77XX_BLACK);
for (int16_t x=0; x < tft.width(); x+=6) {
tft.drawLine(tft.width()-1, 0, x, tft.height()-1, color);
delay(0);
}
for (int16_t y=0; y < tft.height(); y+=6) {
tft.drawLine(tft.width()-1, 0, 0, y, color);
delay(0);
}
tft.fillScreen(ST77XX_BLACK);
for (int16_t x=0; x < tft.width(); x+=6) {
tft.drawLine(0, tft.height()-1, x, 0, color);
delay(0);
}
for (int16_t y=0; y < tft.height(); y+=6) {
tft.drawLine(0, tft.height()-1, tft.width()-1, y, color);
delay(0);
}
tft.fillScreen(ST77XX_BLACK);
for (int16_t x=0; x < tft.width(); x+=6) {
tft.drawLine(tft.width()-1, tft.height()-1, x, 0, color);
delay(0);
}
for (int16_t y=0; y < tft.height(); y+=6) {
tft.drawLine(tft.width()-1, tft.height()-1, 0, y, color);
delay(0);
}
}
void testdrawtext(char *text, uint16_t color) {
tft.setCursor(0, 0);
tft.setTextColor(color);
tft.setTextWrap(true);
tft.print(text);
}
void testfastlines(uint16_t color1, uint16_t color2) {
tft.fillScreen(ST77XX_BLACK);
for (int16_t y=0; y < tft.height(); y+=5) {
tft.drawFastHLine(0, y, tft.width(), color1);
}
for (int16_t x=0; x < tft.width(); x+=5) {
tft.drawFastVLine(x, 0, tft.height(), color2);
}
}
void testdrawrects(uint16_t color) {
tft.fillScreen(ST77XX_BLACK);
for (int16_t x=0; x < tft.width(); x+=6) {
tft.drawRect(tft.width()/2 -x/2, tft.height()/2 -x/2 , x, x, color);
}
}
void testfillrects(uint16_t color1, uint16_t color2) {
tft.fillScreen(ST77XX_BLACK);
for (int16_t x=tft.width()-1; x > 6; x-=6) {
tft.fillRect(tft.width()/2 -x/2, tft.height()/2 -x/2 , x, x, color1);
tft.drawRect(tft.width()/2 -x/2, tft.height()/2 -x/2 , x, x, color2);
}
}
void testfillcircles(uint8_t radius, uint16_t color) {
for (int16_t x=radius; x < tft.width(); x+=radius*2) {
for (int16_t y=radius; y < tft.height(); y+=radius*2) {
tft.fillCircle(x, y, radius, color);
}
}
}
void testdrawcircles(uint8_t radius, uint16_t color) {
for (int16_t x=0; x < tft.width()+radius; x+=radius*2) {
for (int16_t y=0; y < tft.height()+radius; y+=radius*2) {
tft.drawCircle(x, y, radius, color);
}
}
}
void testtriangles() {
tft.fillScreen(ST77XX_BLACK);
uint16_t color = 0xF800;
int t;
int w = tft.width()/2;
int x = tft.height()-1;
int y = 0;
int z = tft.width();
for(t = 0 ; t <= 15; t++) {
tft.drawTriangle(w, y, y, x, z, x, color);
x-=4;
y+=4;
z-=4;
color+=100;
}
}
void testroundrects() {
tft.fillScreen(ST77XX_BLACK);
uint16_t color = 100;
int i;
int t;
for(t = 0 ; t <= 4; t+=1) {
int x = 0;
int y = 0;
int w = tft.width()-2;
int h = tft.height()-2;
for(i = 0 ; i <= 16; i+=1) {
tft.drawRoundRect(x, y, w, h, 5, color);
x+=2;
y+=3;
w-=4;
h-=6;
color+=1100;
}
color+=100;
}
}
void tftPrintTest() {
tft.setTextWrap(false);
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!");
tft.setTextColor(ST77XX_GREEN);
tft.setTextSize(3);
tft.println("Hello World!");
tft.setTextColor(ST77XX_BLUE);
tft.setTextSize(4);
tft.print(1234.567);
delay(1500);
tft.setCursor(0, 0);
tft.fillScreen(ST77XX_BLACK);
tft.setTextColor(ST77XX_WHITE);
tft.setTextSize(0);
tft.println("Hello World!");
tft.setTextSize(1);
tft.setTextColor(ST77XX_GREEN);
tft.print(p, 6);
tft.println(" Want pi?");
tft.println(" ");
tft.print(8675309, HEX); // print 8,675,309 out in HEX!
tft.println(" Print HEX!");
tft.println(" ");
tft.setTextColor(ST77XX_WHITE);
tft.println("Sketch has been");
tft.println("running for: ");
tft.setTextColor(ST77XX_MAGENTA);
tft.print(millis() / 1000);
tft.setTextColor(ST77XX_WHITE);
tft.print(" seconds.");
}
void mediabuttons() {
// play
tft.fillScreen(ST77XX_BLACK);
tft.fillRoundRect(25, 10, 78, 60, 8, ST77XX_WHITE);
tft.fillTriangle(42, 20, 42, 60, 90, 40, ST77XX_RED);
delay(500);
// pause
tft.fillRoundRect(25, 90, 78, 60, 8, ST77XX_WHITE);
tft.fillRoundRect(39, 98, 20, 45, 5, ST77XX_GREEN);
tft.fillRoundRect(69, 98, 20, 45, 5, ST77XX_GREEN);
delay(500);
// play color
tft.fillTriangle(42, 20, 42, 60, 90, 40, ST77XX_BLUE);
delay(50);
// pause color
tft.fillRoundRect(39, 98, 20, 45, 5, ST77XX_RED);
tft.fillRoundRect(69, 98, 20, 45, 5, ST77XX_RED);
// play color
tft.fillTriangle(42, 20, 42, 60, 90, 40, ST77XX_GREEN);
}
Page last edited January 20, 2025
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