Using the 240x240 Round TFT Display with Arduino involves wiring up the display to your Arduino-compatible board, installing the libraries and running the provided example code.
You can wire up the display with a breadboard or using an EYESPI breakout board.
Our most recent display breakouts have come with a new feature: an 18-pin "EYE SPI" standard FPC...
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Connect this to that when a 18-pin FPC connector is needed. This 25 cm long cable is made of a flexible PCB. It's A-B style which means that pin one on one side will match...
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Wiring
Wire as shown for a 5V board like an Uno. If you are using a 3V board, like an Adafruit Feather, wire the board's 3V pin to the breakout VDD.
Here is an Adafruit Metro wired up to the TFT with an EYESPI breakout.
- Board 5V to breakout VIN (red wire)
- Board GND to breakout GND (black wire)
- Board pin 13 to breakout SCK (blue wire)
- Board pin 12 to breakout MISO (green wire)
- Board pin 11 to breakout MOSI (yellow wire)
- Board pin 10 to breakout TCS (purple wire)
- Board pin 9 to breakout RST (orange wire)
- Board pin 8 to breakout DC (white wire)
Attach the TFT screen to the EYESPI breakout with an EYESPI cable as described on the Plugging in an EYESPI Cable page.
The following is the TFT wired to an Adafruit Metro using a solderless breadboard:
- Board 5V to TFT VIN (red wire)
- Board GND to TFT GND (black wire)
- Board pin 13 to TFT SCK (blue wire)
- Board pin 12 to TFT MISO (green wire)
- Board pin 11 to TFT MOSI (yellow wire)
- Board pin 10 to TFT TCS (purple wire)
- Board pin 9 to TFT RST (orange wire)
- Board pin 8 to TFT DC (white wire)
Library Installation
You can install the Adafruit GC9A01A library for Arduino using the Library Manager in the Arduino IDE.
Click the Manage Libraries ... menu item, search for Adafruit GC9A01A, and select the Adafruit GC9A01A library:
If asked about dependencies, click "Install all".
If the "Dependencies" window does not come up, then you already have the dependencies installed.
If the dependencies are already installed, you must make sure you update them through the Arduino Library Manager before loading the example!
// SPDX-FileCopyrightText: 2022 Phillip Burgess for Adafruit Industries
//
// SPDX-License-Identifier: MIT
// Graphics example for EYESPI-capable color displays. This code:
// - Functions as a "Hello World" to verify that microcontroller and screen
// are communicating.
// - Demonstrates most of the drawing commands of the Adafruit_GFX library.
// - Showcases some techniques that might not be obvious or that aren't
// built-in but can be handled with a little extra code.
// It DOES NOT:
// - Support all Adafruit screens, ONLY EYESPI products at the time this was
// written! But it's easily adapted by looking at other examples.
// - Demonstrate the Adafruit_GFX_Button class, as that's unique to
// touch-capable displays. Again, other examples may cover this topic.
// This sketch is long, but a lot of it is comments to explain each step. You
// can copy just the parts you need as a starting point for your own projects,
// and strip comments once understood.
// CONSTANTS, HEADERS and GLOBAL VARIABLES ---------------------------------
// *** EDIT THIS VALUE TO MATCH THE ADAFRUIT PRODUCT ID FOR YOUR DISPLAY: ***
#define SCREEN_PRODUCT_ID 6178 // GC9A01A 240x240 round display
// You can find the product ID several ways:
// - "PID" accompanies each line-item on your receipt or order details page.
// - Visit adafruit.com and search for EYESPI displays. On product pages,
// PID is shown just below product title, and is at the end of URLs.
// - Check the comments in setup() later that reference various screens.
// **** EDIT PINS TO MATCH YOUR WIRING ****
#define TFT_CS 10 // To display chip-select pin
#define TFT_RST 9 // To display reset pin
#define TFT_DC 8 // To display data/command pin
// For the remaining pins, this code assumes display is wired to hardware SPI
// on the dev board's primary SPI interface. The display libraries can support
// secondary SPI (if present) or bitbang (software) SPI, but that's not
// demonstrated here. See other examples for more varied interfacing options.
#include <SPI.h>
#include <Adafruit_GFX.h> // Core graphics library
#include <Fonts/FreeSansBold18pt7b.h> // A custom font
#if (SCREEN_PRODUCT_ID == 1480) || (SCREEN_PRODUCT_ID == 2090)
#include <Adafruit_ILI9341.h> // Library for ILI9341-based screens
Adafruit_ILI9341 display(TFT_CS, TFT_DC, TFT_RST);
#elif (SCREEN_PRODUCT_ID == 6178)
#include "Adafruit_GC9A01A.h"
Adafruit_GC9A01A display(TFT_CS, TFT_DC, TFT_RST);
#else
#include <Adafruit_ST7789.h> // Library for ST7789-based screens
Adafruit_ST7789 display(TFT_CS, TFT_DC, TFT_RST);
#endif
#define PAUSE 3000 // Delay (millisecondss) between examples
uint8_t rotate = 0; // Current screen orientation (0-3)
// setup() RUNS ONCE AT PROGRAM STARTUP ------------------------------------
void setup() {
// Initialize display hardware
#if (SCREEN_PRODUCT_ID == 5393) // 1.47" 320x172 round-rect TFT
#define CORNER_RADIUS 22
display.init(172, 320);
#elif (SCREEN_PRODUCT_ID == 3787) // 240x240 TFT
display.init(240, 240);
#elif (SCREEN_PRODUCT_ID == 5206) // 1.69" 280x240 round-rect TFT
#define CORNER_RADIUS 43
display.init(240, 280);
#elif (SCREEN_PRODUCT_ID == 5394) // 1.9" 320x170 TFT
display.init(170, 320);
#elif (SCREEN_PRODUCT_ID == 6113)
display.init(135, 240);
#else
#define CORNER_RADIUS 45// All ILI9341 & GC9A01A TFTs (320x240)/(240x240)
display.begin();
#endif
#if !defined(CORNER_RADIUS)
#define CORNER_RADIUS 0
#endif
// OPTIONAL: default TFT SPI speed is fairly conservative, you can try
// overriding here for faster screen updates. Actual SPI speed may be less
// depending on microcontroller's capabilities. Max reliable speed also
// depends on wiring length and tidyness.
//display.setSPISpeed(40000000);
}
// MAIN LOOP, REPEATS FOREVER ----------------------------------------------
void loop() {
// Each of these functions demonstrates a different Adafruit_GFX concept:
show_shapes();
show_charts();
show_basic_text();
show_char_map();
show_custom_text();
show_bitmap();
#if !defined(AVR)
// The full set of examples (plus the custom font) won't fit on an 8-bit
// Arduino, something's got to go. You can try out this one IF the other
// examples are disabled instead.
show_canvas();
#endif
if (++rotate > 3) rotate = 0; // Cycle through screen rotations 0-3
display.setRotation(rotate); // Takes effect on next drawing command
}
// BASIC SHAPES EXAMPLE ----------------------------------------------------
void show_shapes() {
const int16_t cx = display.width() / 2; // Center of screen =
const int16_t cy = display.height() / 2; // half of width, height
int16_t minor = min(cx, cy); // Lesser of half width or height
// Shapes will be drawn in a square region centered on the screen. But one
// particular screen -- rounded 240x280 ST7789 -- has VERY rounded corners
// that would clip a couple of shapes if drawn full size. If using that
// screen type, reduce area by a few pixels to avoid drawing in corners.
const uint8_t pad = 5; // Space between shapes is 2X this
const int16_t size = minor - pad; // Shapes are this width & height
const int16_t half = size / 2; // 1/2 of shape size
// Rectangle
display.fillScreen(0);
display.drawRect(cx - half, cy - half, size, size, 0xF800);
delay(500);
display.fillScreen(0);
display.fillRect(cx - half, cy - half, size, size, 0xF800);
delay(500);
// Triangle
display.fillScreen(0);
display.drawTriangle(
cx, cy - half, // Top
cx - half, cy + half, // Bottom left
cx + half, cy + half, // Bottom right
0x07E0
);
delay(500);
display.fillScreen(0);
display.fillTriangle(
cx, cy - half, // Top
cx - half, cy + half, // Bottom left
cx + half, cy + half, // Bottom right
0x07E0
);
delay(500);
// Circle
display.fillScreen(0);
display.drawCircle(cx, cy, half, 0x001F);
delay(500);
display.fillScreen(0);
display.fillCircle(cx, cy, half, 0x001F);
delay(500);
// Rounded Rectangle
display.fillScreen(0);
display.drawRoundRect(cx - half, cy - half, size, size, size/5, 0xFFE0);
delay(500);
display.fillScreen(0);
display.fillRoundRect(cx - half, cy - half, size, size, size/5, 0xFFE0);
delay(500);
}
// CHART EXAMPLES ----------------------------------------------------------
void show_charts() {
// Draw some graphs and charts. GFX library doesn't handle these as native
// object types, but it only takes a little code to build them from simple
// shapes. This demonstrates:
// - Drawing points and horizontal, vertical and arbitrary lines.
// - Adapting to different-sized displays.
// - Graphics being clipped off edge.
// - Use of negative values to draw shapes "backward" from an anchor point.
// - C technique for finding array size at runtime (vs hardcoding).
display.fillScreen(0); // Clear screen
const int16_t cx = display.width() / 2; // Center of screen =
const int16_t cy = display.height() / 2; // half of width, height
const int16_t minor = min(cx, cy); // Lesser of half width or height
const int16_t major = max(cx, cy); // Greater of half width or height
// Let's start with a relatively simple sine wave graph with axes.
// Draw graph axes centered on screen. drawFastHLine() and drawFastVLine()
// need fewer arguments than normal 2-point line drawing shown later.
display.drawFastHLine(0, cy, display.width(), 0x0210); // Dark blue
display.drawFastVLine(cx, 0, display.height(), 0x0210);
// Then draw some tick marks along the axes. To keep this code simple,
// these aren't to any particular scale, but a real program may want that.
// The loop here draws them from the center outward and pays no mind
// whether the screen is rectangular; any ticks that go off-screen will
// be clipped by the library.
for (uint8_t i=1; i<=10; i++) {
// The Arduino map() function scales an input value (e.g. "i") from an
// input range (0-10 here) to an output range (0 to major-1 here).
// Very handy for making graphics adjust to different screens!
int16_t n = map(i, 0, 10, 0, major - 1); // Tick offset relative to center point
display.drawFastVLine(cx - n, cy - 5, 11, 0x210);
display.drawFastVLine(cx + n, cy - 5, 11, 0x210);
display.drawFastHLine(cx - 5, cy - n, 11, 0x210);
display.drawFastHLine(cx - 5, cy + n, 11, 0x210);
}
// Then draw sine wave over this using GFX drawPixel() function.
for (int16_t x=0; x<display.width(); x++) { // Each column of screen...
// Note the inverted Y axis here (cy-value rather than cy+value)
// because GFX, like most graphics libraries, has +Y heading down,
// vs. classic Cartesian coords which have +Y heading up.
int16_t y = cy - (int16_t)(sin((x - cx) * 0.05) * (float)minor * 0.5);
display.drawPixel(x, y, 0xFFFF);
}
delay(PAUSE);
} // END CHART EXAMPLES
// TEXT ALIGN FUNCTIONS ----------------------------------------------------
// Adafruit_GFX only handles left-aligned text. This is normal and by design;
// it's a rare need that would further strain AVR by incurring a ton of extra
// code to properly handle, and some details would confuse. If needed, these
// functions give a fair approximation, with the "gotchas" that multi-line
// input won't work, and this operates only as a println(), not print()
// (though, unlike println(), cursor X does not reset to column 0, instead
// returning to initial column and downward by font's line spacing). If you
// can work with those constraints, it's a modest amount of code to copy
// into a project. Or, if your project only needs one or two aligned strings,
// simply use getTextBounds() for a bounding box and work from there.
// DO NOT ATTEMPT TO MAKE THIS A GFX-NATIVE FEATURE, EVERYTHING WILL BREAK.
typedef enum { // Alignment options passed to functions below
GFX_ALIGN_LEFT,
GFX_ALIGN_CENTER,
GFX_ALIGN_RIGHT
} GFXalign;
// Draw text aligned relative to current cursor position. Arguments:
// gfx : An Adafruit_GFX-derived type (e.g. display or canvas object).
// str : String to print (as a char *).
// align : One of the GFXalign values declared above.
// GFX_ALIGN_LEFT is normal left-aligned println() behavior.
// GFX_ALIGN_CENTER prints centered on cursor pos.
// GFX_ALIGN_RIGHT prints right-aligned to cursor pos.
// Cursor advances down one line a la println(). Column is unchanged.
void print_aligned(Adafruit_GFX &gfx, const char *str,
GFXalign align = GFX_ALIGN_LEFT) {
uint16_t w, h;
int16_t x, y, cursor_x, cursor_x_save;
cursor_x = cursor_x_save = gfx.getCursorX();
gfx.getTextBounds(str, 0, gfx.getCursorY(), &x, &y, &w, &h);
if (align == GFX_ALIGN_RIGHT) cursor_x -= w;
else if (align == GFX_ALIGN_CENTER) cursor_x -= w / 2;
//gfx.drawRect(cursor_x, y, w, h, 0xF800); // Debug rect
gfx.setCursor(cursor_x - x, gfx.getCursorY()); // Center/right align
gfx.println(str);
gfx.setCursor(cursor_x_save, gfx.getCursorY()); // Restore cursor X
}
// Equivalent function for strings in flash memory (e.g. F("Foo")). Body
// appears identical to above function, but with C++ overloading it it works
// from flash instead of RAM. Any changes should be made in both places.
void print_aligned(Adafruit_GFX &gfx, const __FlashStringHelper *str,
GFXalign align = GFX_ALIGN_LEFT) {
uint16_t w, h;
int16_t x, y, cursor_x, cursor_x_save;
cursor_x = cursor_x_save = gfx.getCursorX();
gfx.getTextBounds(str, 0, gfx.getCursorY(), &x, &y, &w, &h);
if (align == GFX_ALIGN_RIGHT) cursor_x -= w;
else if (align == GFX_ALIGN_CENTER) cursor_x -= w / 2;
//gfx.drawRect(cursor_x, y, w, h, 0xF800); // Debug rect
gfx.setCursor(cursor_x - x, gfx.getCursorY()); // Center/right align
gfx.println(str);
gfx.setCursor(cursor_x_save, gfx.getCursorY()); // Restore cursor X
}
// Equivalent function for Arduino Strings; converts to C string (char *)
// and calls corresponding print_aligned() implementation.
void print_aligned(Adafruit_GFX &gfx, const String &str,
GFXalign align = GFX_ALIGN_LEFT) {
print_aligned(gfx, const_cast<char *>(str.c_str()));
}
// TEXT EXAMPLES -----------------------------------------------------------
// This section demonstrates:
// - Using the default 5x7 built-in font, including scaling in each axis.
// - How to access all characters of this font, including symbols.
// - Using a custom font, including alignment techniques that aren't a normal
// part of the GFX library (uses functions above).
void show_basic_text() {
// Show text scaling with built-in font.
display.fillScreen(0);
display.setFont(); // Use default font
display.setCursor(50, CORNER_RADIUS); // Initial cursor position
display.setTextSize(1); // Default size
display.println(F("Standard built-in font"));
display.setTextSize(2);
display.setCursor(30, display.getCursorY());
display.println(F("BIG TEXT"));
display.setTextSize(3);
// "BIGGER TEXT" won't fit on narrow screens, so abbreviate there.
display.setCursor(20, display.getCursorY());
display.println((display.width() >= 200) ? F("BIGGER TEXT") : F("BIGGER"));
display.setTextSize(2, 4);
display.setCursor(15, display.getCursorY());
display.println(F("TALL and"));
display.setCursor(15, display.getCursorY());
display.setTextSize(4, 2);
display.println(F("WIDE"));
delay(PAUSE);
} // END BASIC TEXT EXAMPLE
void show_char_map() {
// "Code Page 437" is a name given to the original IBM PC character set.
// Despite age and limited language support, still seen in small embedded
// settings as it has some useful symbols and accented characters. The
// default 5x7 pixel font of Adafruit_GFX is modeled after CP437. This
// function draws a table of all the characters & explains some issues.
// There are 256 characters in all. Draw table as 16 rows of 16 columns,
// plus hexadecimal row & column labels. How big can each cell be drawn?
const int cell_size = min(display.width(), display.height()) / 17;
if (cell_size < 8) return; // Screen is too small for table, skip example.
const int total_size = cell_size * 17; // 16 cells + 1 row or column label
// Set up for default 5x7 font at 1:1 scale. Custom fonts are NOT used
// here as most are only 128 characters to save space (the "7b" at the
// end of many GFX font names means "7 bits," i.e. 128 characters).
display.setFont();
display.setTextSize(1);
// Early Adafruit_GFX was missing one symbol, throwing off some indices!
// But fixing the library would break MANY existing sketches that relied
// on the degrees symbol and others. The default behavior is thus "broken"
// to keep older code working. New code can access the CORRECT full CP437
// table by calling this function like so:
display.cp437(true);
display.fillScreen(0);
const int16_t x = (display.width() - total_size) / 2; // Upper left corner of
int16_t y = (display.height() - total_size) / 2; // table centered on screen
if (y >= 4) { // If there's a little extra space above & below, scoot table
y += 4; // down a few pixels and show a message centered at top.
display.setCursor((display.width() - 114) / 2, 0); // 114 = pixel width
display.print(F("CP437 Character Map")); // of this message
}
const int16_t inset_x = (cell_size - 5) / 2; // To center each character within cell,
const int16_t inset_y = (cell_size - 8) / 2; // compute X & Y offset from corner.
for (uint8_t row=0; row<16; row++) { // 16 down...
// Draw row and columm headings as hexadecimal single digits. To get the
// hex value for a specific character, combine the left & top labels,
// e.g. Pi symbol is row E, column 3, thus: display.print((char)0xE3);
display.setCursor(x + (row + 1) * cell_size + inset_x, y + inset_y);
display.print(row, HEX); // This actually draws column labels
display.setCursor(x + inset_x, y + (row + 1) * cell_size + inset_y);
display.print(row, HEX); // and THIS is the row labels
for (uint8_t col=0; col<16; col++) { // 16 across...
if ((row + col) & 1) { // Fill alternating cells w/gray
display.fillRect(x + (col + 1) * cell_size, y + (row + 1) * cell_size,
cell_size, cell_size, 0x630C);
}
// drawChar() bypasses usual cursor positioning to go direct to an X/Y
// location. If foreground & background match, it's drawn transparent.
display.drawChar(x + (col + 1) * cell_size + inset_x,
y + (row + 1) * cell_size + inset_y, row * 16 + col,
0xFFFF, 0xFFFF, 1);
}
}
delay(PAUSE * 2);
} // END CHAR MAP EXAMPLE
void show_custom_text() {
// Show use of custom fonts, plus how to do center or right alignment
// using some additional functions provided earlier.
display.fillScreen(0);
display.setFont(&FreeSansBold18pt7b);
display.setTextSize(1);
display.setTextWrap(false); // Allow text off edges
// Get "M height" of custom font and move initial base line there:
uint16_t w, h;
int16_t x, y;
display.getTextBounds("M", 0, 0, &x, &y, &w, &h);
// On rounded 240x280 display in tall orientation, "Custom Font" gets
// clipped by top corners. Scoot text down a few pixels in that one case.
if ((CORNER_RADIUS && (display.height() == 280)) || (SCREEN_PRODUCT_ID == 6178)) h += 20;
display.setCursor(display.width() / 2, h);
if ((display.width() >= 200) && (SCREEN_PRODUCT_ID != 6178)) {
print_aligned(display, F("Custom Font"), GFX_ALIGN_CENTER);
display.setCursor(0, display.getCursorY() + 10);
print_aligned(display, F("Align Left"), GFX_ALIGN_LEFT);
display.setCursor(display.width() / 2, display.getCursorY());
print_aligned(display, F("Centered"), GFX_ALIGN_CENTER);
// Small rounded screen, when oriented the wide way, "Right" gets
// clipped by bottom right corner. Scoot left to compensate.
int16_t x_offset = (CORNER_RADIUS && (display.height() < 200)) ? 15 : 0;
display.setCursor(display.width() - x_offset, display.getCursorY());
print_aligned(display, F("Align Right"), GFX_ALIGN_RIGHT);
} else {
display.setCursor(display.width() / 2, display.height() / 2);
print_aligned(display, F("Custom Font"), GFX_ALIGN_CENTER);
}
delay(PAUSE);
} // END CUSTOM FONT EXAMPLE
// BITMAP EXAMPLE ----------------------------------------------------------
// This section demonstrates:
// - Embedding a small bitmap in the code (flash memory).
// - Drawing that bitmap in various colors, and transparently (only '1' bits
// are drawn; '0' bits are skipped, leaving screen contents in place).
// - Use of the color565() function to decimate 24-bit RGB to 16 bits.
#define HEX_WIDTH 16 // Bitmap width in pixels
#define HEX_HEIGHT 16 // Bitmap height in pixels
// Bitmap data. PROGMEM ensures it's in flash memory (not RAM). And while
// it would be valid to leave the brackets empty here (i.e. hex_bitmap[]),
// having dimensions with a little math makes the compiler verify the
// correct number of bytes are present in the list.
PROGMEM const uint8_t hex_bitmap[(HEX_WIDTH + 7) / 8 * HEX_HEIGHT] = {
0b00000001, 0b10000000,
0b00000111, 0b11100000,
0b00011111, 0b11111000,
0b01111111, 0b11111110,
0b01111111, 0b11111110,
0b01111111, 0b11111110,
0b01111111, 0b11111110,
0b01111111, 0b11111110,
0b01111111, 0b11111110,
0b01111111, 0b11111110,
0b01111111, 0b11111110,
0b01111111, 0b11111110,
0b01111111, 0b11111110,
0b00011111, 0b11111000,
0b00000111, 0b11100000,
0b00000001, 0b10000000,
};
#define Y_SPACING (HEX_HEIGHT - 2) // Used by code below for positioning
void show_bitmap() {
display.fillScreen(0);
// Not screen center, but UL coordinates of center hexagon bitmap
const int16_t center_x = (display.width() - HEX_WIDTH) / 2;
const int16_t center_y = (display.height() - HEX_HEIGHT) / 2;
const uint8_t steps = min((display.height() - HEX_HEIGHT) / Y_SPACING,
display.width() / HEX_WIDTH - 1) / 2;
display.drawBitmap(center_x, center_y, hex_bitmap, HEX_WIDTH, HEX_HEIGHT,
0xFFFF); // Draw center hexagon in white
// Tile the hexagon bitmap repeatedly in a range of hues. Don't mind the
// bit of repetition in the math, the optimizer easily picks this up.
// Also, if math looks odd, keep in mind "PEMDAS" operator precedence;
// multiplication and division occur before addition and subtraction.
for (uint8_t a=0; a<=steps; a++) {
for (uint8_t b=1; b<=steps; b++) {
display.drawBitmap( // Right section centered red: a = green, b = blue
center_x + (a + b) * HEX_WIDTH / 2,
center_y + (a - b) * Y_SPACING,
hex_bitmap, HEX_WIDTH, HEX_HEIGHT,
display.color565(255, 255 - 255 * a / steps, 255 - 255 * b / steps));
display.drawBitmap( // UL section centered green: a = blue, b = red
center_x - b * HEX_WIDTH + a * HEX_WIDTH / 2,
center_y - a * Y_SPACING,
hex_bitmap, HEX_WIDTH, HEX_HEIGHT,
display.color565(255 - 255 * b / steps, 255, 255 - 255 * a / steps));
display.drawBitmap( // LL section centered blue: a = red, b = green
center_x - a * HEX_WIDTH + b * HEX_WIDTH / 2,
center_y + b * Y_SPACING,
hex_bitmap, HEX_WIDTH, HEX_HEIGHT,
display.color565(255 - 255 * a / steps, 255 - 255 * b / steps, 255));
}
}
delay(PAUSE);
} // END BITMAP EXAMPLE
// CANVAS EXAMPLE ----------------------------------------------------------
// This section demonstrates:
// - How to refresh changing values onscreen without erase/redraw flicker.
// - Using an offscreen canvas. It's similar to a bitmap above, but rather
// than a fixed pattern in flash memory, it's drawable like the screen.
// - More tips on text alignment, and adapting to different screen sizes.
#define PADDING 6 // Pixels between axis label and value
void show_canvas() {
// For this example, let's suppose we want to display live readings from a
// sensor such as a three-axis accelerometer, something like:
// X: (number)
// Y: (number)
// Z: (number)
// To look extra classy, we want a custom font, and the labels for each
// axis are right-aligned so the ':' characters line up...
display.setFont(&FreeSansBold18pt7b); // Use a custom font
display.setTextSize(1); // and reset to 1:1 scale
const char *label[] = { "X:", "Y:", "Z:" }; // Labels for each axis
const uint16_t color[] = { 0xF800, 0x07E0, 0x001F }; // Colors for each value
// To get the labels right-aligned, one option would be simple trial and
// error to find a column that looks good and doesn't clip anything off.
// Let's do this dynamically though, so it adapts to any font or labels!
// Start by finding the widest of the label strings:
uint16_t w, h, max_w = 0;
int16_t x, y;
for (uint8_t i=0; i<3; i++) { // For each label...
display.getTextBounds(label[i], 0, 0, &x, &y, &w, &h);
if (w > max_w) max_w = w; // Keep track of widest label
}
// Rounded corners throwing us a curve again. If needed, scoot everything
// to the right a bit on wide displays, down a bit on tall ones.
int16_t y_offset = 0;
if (display.width() > display.height()) max_w += CORNER_RADIUS;
else y_offset = CORNER_RADIUS;
// Now we have max_w for right-aligning the labels. Before we draw them
// though...in order to perform flicker-free updates, the numbers we show
// will be rendered in either a GFXcanvas1 or GFXcanvas16 object; a 1-bit
// or 16-bit offscreen bitmap, RAM permitting. The correct size for this
// canvas could also be trial-and-errored, but again let's make this adapt
// automatically. The width of the canvas will span from max_w (plus a few
// pixels for padding) to the right edge. But the height? Looking at an
// uppercase 'M' can work in many situations, but some fonts have ascenders
// and descenders on digits, and in some locales a comma (extending below
// the baseline) is the decimal separator. Feed ALL the numeric chars into
// getTextBounds() for a cumulative height:
display.setTextWrap(false); // Keep on one line
display.getTextBounds(F("0123456789.,-"), 0, 0, &x, &y, &w, &h);
// Now declare a GFXcanvas16 object based on the computed width & height:
GFXcanvas16 canvas16(display.width() - max_w - PADDING, h);
// Small devices (e.g. ATmega328p) will almost certainly lack enough RAM
// for the canvas. Check if canvas buffer exists. If not, fall back on
// using a 1-bit (rather than 16-bit) canvas. Much more RAM friendly, but
// not as fast to draw. If a project doesn't require super interactive
// updates, consider just going straight for the more compact Canvas1.
if (canvas16.getBuffer()) {
// If here, 16-bit canvas allocated successfully! Point of interest,
// only one canvas is needed for this example, we can reuse it for all
// three numbers because the regions are the same size.
// display and canvas are independent drawable objects; must explicitly
// set the same custom font to use on the canvas now:
canvas16.setFont(&FreeSansBold18pt7b);
// Clear display and print labels. Once drawn, these remain untouched.
display.fillScreen(0);
display.setCursor(max_w, -y + y_offset); // Set baseline for first row
for (uint8_t i=0; i<3; i++) print_aligned(display, label[i], GFX_ALIGN_RIGHT);
// Last part now is to print numbers on the canvas and copy the canvas to
// the display, repeating for several seconds...
uint32_t elapsed, startTime = millis();
while ((elapsed = (millis() - startTime)) <= PAUSE * 2) {
for (uint8_t i=0; i<3; i++) { // For each label...
canvas16.fillScreen(0); // fillScreen() in this case clears canvas
canvas16.setCursor(0, -y); // Reset baseline for custom font
canvas16.setTextColor(color[i]);
// These aren't real accelerometer readings, just cool-looking numbers.
// Notice we print to the canvas, NOT the display:
canvas16.print(sin(elapsed / 200.0 + (float)i * M_PI * 2.0 / 3.0), 5);
// And HERE is the secret sauce to flicker-free updates. Canvas details
// can be passed to the drawRGBBitmap() function, which fully overwrites
// prior screen contents in that area. yAdvance is font line spacing.
display.drawRGBBitmap(max_w + PADDING, i * FreeSansBold18pt7b.yAdvance +
y_offset, canvas16.getBuffer(), canvas16.width(),
canvas16.height());
}
}
} else {
// Insufficient RAM for Canvas16. Try declaring a 1-bit canvas instead...
GFXcanvas1 canvas1(display.width() - max_w - PADDING, h);
// If even this smaller object fails, can't proceed, cancel this example.
if (!canvas1.getBuffer()) return;
// Remainder here is nearly identical to the code above, simply using a
// different canvas type. It's stripped of most comments for brevity.
canvas1.setFont(&FreeSansBold18pt7b);
display.fillScreen(0);
display.setCursor(max_w, -y + y_offset);
for (uint8_t i=0; i<3; i++) print_aligned(display, label[i], GFX_ALIGN_RIGHT);
uint32_t elapsed, startTime = millis();
while ((elapsed = (millis() - startTime)) <= PAUSE * 2) {
for (uint8_t i=0; i<3; i++) {
canvas1.fillScreen(0);
canvas1.setCursor(0, -y);
canvas1.print(sin(elapsed / 200.0 + (float)i * M_PI * 2.0 / 3.0), 5);
// Here's the secret sauce to flicker-free updates with GFXcanvas1.
// Canvas details can be passed to the drawBitmap() function, and by
// specifying both a foreground AND BACKGROUND color (0), this will fully
// overwrite/erase prior screen contents in that area (vs transparent).
display.drawBitmap(max_w + PADDING, i * FreeSansBold18pt7b.yAdvance +
y_offset, canvas1.getBuffer(), canvas1.width(),
canvas1.height(), color[i], 0);
}
}
}
// Because canvas object was declared locally to this function, it's freed
// automatically when the function returns; no explicit delete needed.
} // END CANVAS EXAMPLE
Upload the sketch to your board. You should see a modified graphics test begin running on your display. The tests include drawing shapes, graphs and text. After every loop of the test, the code will rotate the screen orientation by 90 degrees and run the test again. The code is heavily commented so you can utilize the examples for various graphic techniques in your projects.
Page last edited February 11, 2025
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