This tutorial explains how to use an ILI9341 with a touchscreen driven by an esp32-s2!
Supplies
- (1) esp32-s2-12k
- (13) Jumper wires
- (1) ILI9341 with Touchscreen
For refrence I have included the pinout diagram for the esp32-c3-32s that I am using.
Pinout diagram for the esp32-s2-12k from Ai-Thinker
I have included the specsheet for this chip in case it is removed, the original source location is https://docs.ai-thinker.com/en/12k_development_board_esp32-s2
Checkup
It's always good to double-check we are using the right screen as many screens look touch-capable but are not. Check out the steps to make sure they are by reading https://www.gabrielcsapo.com/hardware-how-to-identify-an-ili9341-that-supports-touch/.
Setup
Alright, now that we have figured out if the touchscreen you have is touch-capable, time to set up the esp32-s2-12k and the ILI9341 display.
| esp32-s2-12k Pins | TFT Pins |
|---|---|
| 3V3 | VCC |
| GND | GND |
| 10 | CS |
| 15 | RESET |
| 11 | SDI (MOSI) |
| 12 | SCK |
| 3V3 | LED |
| 12 | T_CLK |
| 34 | T_CS |
| 11 | T_DIN |
| 13 | T_DO |
Coding
There are, like most things, multiple ways you can program this board to support touch and display out.
Flash settings
- USB CDC on boot: disabled
- Board: ESP32S2 Dev Modules
- CPU Frequency: 240MHZ
- Flash Frequency: 40MHZ
- Flash Mode: DIO
- Flash Size: 4MB
- Partition Scheme: Default 4MB with spiffs
- Upload Mode: UARTO
- Upload Speed: 460800
TFT_eSPI
We are using the following libraries:
For information on how to install the libraries above please visisthttps://www.arduino.cc/en/guide/libraries.
Working with TFT_eSPI, you need to edit User_Setup.h it is located in your Arduino folder libraries folder. To find this location check out https://support.arduino.cc/hc/en-us/articles/4411202655634-Find-Arduino-IDE-files-and-folders which has more info on the exact location for your machine.
#define ILI9341_DRIVER
#define TFT_CS 10
#define TFT_MOSI 11
#define TFT_SCLK 12
#define TFT_MISO 13
#define TFT_DC 14
#define TFT_RST 15
#define TOUCH_CS 34
#define LOAD_GLCD
#define LOAD_FONT2
#define LOAD_FONT4
#define LOAD_FONT6
#define LOAD_FONT7
#define LOAD_FONT8
#define LOAD_GFXFF
#define SMOOTH_FONT
#define USE_HSPI_PORT
#define SPI_FREQUENCY 40000000
#define SPI_TOUCH_FREQUENCY 2500000
Once we have the User_Setup.h configured we can use one of the existing sketches. One of the most intricate examples is the keypad example (https://github.com/Bodmer/TFT_eSPI/blob/master/examples/320%20x%20240/Keypad_240x320/Keypad_240x320.ino). It shows off having a single library handle both touch and rendering provides a lot of out of the box wins.
/*The TFT_eSPI library incorporates an Adafruit_GFX compatiblebutton handling class, this sketch is based on the Arduin-o-phoneexample.This example diplays a keypad where numbers can be entered andsend to the Serial Monitor window.The sketch has been tested on the ESP8266 (which supports SPIFFS)The minimum screen size is 320 x 240 as that is the keypad size.*/// The SPIFFS (FLASH filing system) is used to hold touch screen// calibration data#include "FS.h"#include <SPI.h>#include <TFT_eSPI.h> // Hardware-specific libraryTFT_eSPI tft = TFT_eSPI(); // Invoke custom library// This is the file name used to store the calibration data// You can change this to create new calibration files.// The SPIFFS file name must start with "/".#define CALIBRATION_FILE "/TouchCalData1"// Set REPEAT_CAL to true instead of false to run calibration// again, otherwise it will only be done once.// Repeat calibration if you change the screen rotation.#define REPEAT_CAL false// Keypad start position, key sizes and spacing#define KEY_X 40 // Centre of key#define KEY_Y 96#define KEY_W 62 // Width and height#define KEY_H 30#define KEY_SPACING_X 18 // X and Y gap#define KEY_SPACING_Y 20#define KEY_TEXTSIZE 1 // Font size multiplier// Using two fonts since numbers are nice when bold#define LABEL1_FONT &FreeSansOblique12pt7b // Key label font 1#define LABEL2_FONT &FreeSansBold12pt7b // Key label font 2// Numeric display box size and location#define DISP_X 1#define DISP_Y 10#define DISP_W 238#define DISP_H 50#define DISP_TSIZE 3#define DISP_TCOLOR TFT_CYAN// Number length, buffer for storing it and character index#define NUM_LEN 12char numberBuffer[NUM_LEN + 1] = "";uint8_t numberIndex = 0;// We have a status line for messages#define STATUS_X 120 // Centred on this#define STATUS_Y 65// Create 15 keys for the keypadchar keyLabel[15][5] = {"New", "Del", "Send", "1", "2", "3", "4", "5", "6", "7", "8", "9", ".", "0", "#" };uint16_t keyColor[15] = {TFT_RED, TFT_DARKGREY, TFT_DARKGREEN, TFT_BLUE, TFT_BLUE, TFT_BLUE, TFT_BLUE, TFT_BLUE, TFT_BLUE, TFT_BLUE, TFT_BLUE, TFT_BLUE, TFT_BLUE, TFT_BLUE, TFT_BLUE };// Invoke the TFT_eSPI button class and create all the button objectsTFT_eSPI_Button key[15];//------------------------------------------------------------------------------------------void setup() {// Use serial portSerial.begin(9600);// Initialise the TFT screentft.init();// Set the rotation before we calibratetft.setRotation(0);// Calibrate the touch screen and retrieve the scaling factorstouch_calibrate();// Clear the screentft.fillScreen(TFT_BLACK);// Draw keypad backgroundtft.fillRect(0, 0, 240, 320, TFT_DARKGREY);// Draw number display area and frametft.fillRect(DISP_X, DISP_Y, DISP_W, DISP_H, TFT_BLACK);tft.drawRect(DISP_X, DISP_Y, DISP_W, DISP_H, TFT_WHITE);// Draw keypaddrawKeypad();}//------------------------------------------------------------------------------------------void loop(void) {uint16_t t_x = 0, t_y = 0; // To store the touch coordinates// Pressed will be set true is there is a valid touch on the screenbool pressed = tft.getTouch(&t_x, &t_y);// / Check if any key coordinate boxes contain the touch coordinatesfor (uint8_t b = 0; b < 15; b++) { if (pressed && key[b].contains(t_x, t_y)) { key[b].press(true); // tell the button it is pressed } else { key[b].press(false); // tell the button it is NOT pressed }}// Check if any key has changed statefor (uint8_t b = 0; b < 15; b++) { if (b < 3) tft.setFreeFont(LABEL1_FONT); else tft.setFreeFont(LABEL2_FONT); if (key[b].justReleased()) key[b].drawButton(); // draw normal if (key[b].justPressed()) { key[b].drawButton(true); // draw invert // if a numberpad button, append the relevant ## to the numberBuffer if (b >= 3) { if (numberIndex < NUM_LEN) { numberBuffer[numberIndex] = keyLabel[b][0]; numberIndex++; numberBuffer[numberIndex] = 0; // zero terminate } status(""); // Clear the old status } // Del button, so delete last char if (b == 1) { numberBuffer[numberIndex] = 0; if (numberIndex > 0) { numberIndex--; numberBuffer[numberIndex] = 0;//' '; } status(""); // Clear the old status } if (b == 2) { status("Sent value to serial port"); Serial.println(numberBuffer); } // we dont really check that the text field makes sense // just try to call if (b == 0) { status("Value cleared"); numberIndex = 0; // Reset index to 0 numberBuffer[numberIndex] = 0; // Place null in buffer } // Update the number display field tft.setTextDatum(TL_DATUM); // Use top left corner as text coord datum tft.setFreeFont(&FreeSans18pt7b); // Choose a nicefont that fits box tft.setTextColor(DISP_TCOLOR); // Set the font colour // Draw the string, the value returned is the width in pixels int xwidth = tft.drawString(numberBuffer, DISP_X + 4, DISP_Y + 12); // Now cover up the rest of the line up by drawing a black rectangle. No flicker this way // but it will not work with italic or oblique fonts due to character overlap. tft.fillRect(DISP_X + 4 + xwidth, DISP_Y + 1, DISP_W - xwidth - 5, DISP_H - 2, TFT_BLACK); delay(10); // UI debouncing }}}//------------------------------------------------------------------------------------------void drawKeypad(){// Draw the keysfor (uint8_t row = 0; row < 5; row++) { for (uint8_t col = 0; col < 3; col++) { uint8_t b = col + row * 3; if (b < 3) tft.setFreeFont(LABEL1_FONT); else tft.setFreeFont(LABEL2_FONT); key[b].initButton(&tft, KEY_X + col * (KEY_W + KEY_SPACING_X), KEY_Y + row * (KEY_H + KEY_SPACING_Y), // x, y, w, h, outline, fill, text KEY_W, KEY_H, TFT_WHITE, keyColor[b], TFT_WHITE, keyLabel[b], KEY_TEXTSIZE); key[b].drawButton(); }}}//------------------------------------------------------------------------------------------void touch_calibrate(){uint16_t calData[5];uint8_t calDataOK = 0;// check file system existsif (!SPIFFS.begin()) { Serial.println("Formating file system"); SPIFFS.format(); SPIFFS.begin();}// check if calibration file exists and size is correctif (SPIFFS.exists(CALIBRATION_FILE)) { if (REPEAT_CAL) { // Delete if we want to re-calibrate SPIFFS.remove(CALIBRATION_FILE); } else { File f = SPIFFS.open(CALIBRATION_FILE, "r"); if (f) { if (f.readBytes((char *)calData, 14) == 14) calDataOK = 1; f.close(); } }}if (calDataOK && !REPEAT_CAL) { // calibration data valid tft.setTouch(calData);} else { // data not valid so recalibrate tft.fillScreen(TFT_BLACK); tft.setCursor(20, 0); tft.setTextFont(2); tft.setTextSize(1); tft.setTextColor(TFT_WHITE, TFT_BLACK); tft.println("Touch corners as indicated"); tft.setTextFont(1); tft.println(); if (REPEAT_CAL) { tft.setTextColor(TFT_RED, TFT_BLACK); tft.println("Set REPEAT_CAL to false to stop this running again!"); } tft.calibrateTouch(calData, TFT_MAGENTA, TFT_BLACK, 15); tft.setTextColor(TFT_GREEN, TFT_BLACK); tft.println("Calibration complete!"); // store data File f = SPIFFS.open(CALIBRATION_FILE, "w"); if (f) { f.write((const unsigned char *)calData, 14); f.close(); }}}//------------------------------------------------------------------------------------------// Print something in the mini status barvoid status(const char *msg) {tft.setTextPadding(240);//tft.setCursor(STATUS_X, STATUS_Y);tft.setTextColor(TFT_WHITE, TFT_DARKGREY);tft.setTextFont(0);tft.setTextDatum(TC_DATUM);tft.setTextSize(1);tft.drawString(msg, STATUS_X, STATUS_Y);}//------------------------------------------------------------------------------------------Keypad example is taken from https://github.com/Bodmer/TFT_eSPI/blob/master/examples/320%20x%20240/Keypad_240x320/Keypad_240x320.ino.
One of the benefits of using TFT_eSPI is having the ability to calibrate your display and having that as a part of your workflow. This does require SPIFFS to store this information, so having something like the esp32 family is a well-suited library for most of your needs.
Running the previous sketch for keypad showing calibration with keypad application
XPT2046_Touchscreen
Another library that works with this particular touchscreen is XPT2046_Touchscreen.
We are using the following libraries:
For information on how to install the libraries above please visit [_https://www.arduino.cc/en/guide/libraries](https://www.arduino.cc/en/guide/libraries).
We are going to be using a sketch I wrote for https://www.gabrielcsapo.com/arduino-esp32-c3-32s-ili9341-with-touchscreen/.
To look at the most up-to-date sketch you can check it out here.
#include "Adafruit_GFX.h" #include "Adafruit_ILI9341.h" #include <XPT2046_Touchscreen.h> #include <SPI.h> #define SCLK_PIN 12 #define MISO_PIN 13 #define MOSI_PIN 11 #define TOUCH_CS 34 #define TFT_DC 14 #define TFT_CS 10 #define TFT_RST 15 XPT2046_Touchscreen ts(TOUCH_CS); Adafruit_ILI9341 tft = Adafruit_ILI9341(TFT_CS, TFT_DC, TFT_RST); void setup() { Serial.begin(38400); SPI.begin( SCLK_PIN, MISO_PIN, MOSI_PIN ); SPI.setFrequency( 40000000 ); tft.begin(4000000); tft.setRotation(1); tft.fillScreen(ILI9341_BLACK); ts.begin(); ts.setRotation(1); while (!Serial && (millis() <= 1000)); } boolean wastouched = true; void loop() { boolean istouched = ts.touched(); if (istouched) { TS_Point p = ts.getPoint(); if (!wastouched) { tft.fillScreen(ILI9341_BLACK); tft.setTextColor(ILI9341_YELLOW); tft.setCursor(60, 80); tft.print("Touch"); } tft.fillRect(100, 150, 140, 60, ILI9341_BLACK); tft.setTextColor(ILI9341_GREEN); tft.setCursor(100, 150); tft.print("X = "); tft.print(p.x); tft.setCursor(100, 180); tft.print("Y = "); tft.print(p.y); Serial.print(", x = "); Serial.print(p.x); Serial.print(", y = "); Serial.println(p.y); } else { if (wastouched) { tft.fillScreen(ILI9341_BLACK); tft.setTextColor(ILI9341_RED); tft.setCursor(120, 50); tft.print("No"); tft.setCursor(80, 120); tft.print("Touch"); } Serial.println("no touch"); } wastouched = istouched; delay(100); }Sketch for XPT2046_Touchscreen.
Example running the XPT2046_Touchscreen example above.
Conclusion
Picking the right library for your needs is important. There are considerations to be made between XPT2046_Touchscreen and TFT_eSPI such as compatibility and required space to run on your device. I have yet to use either in any real-life application other than some of the two examples provided, when I do I will put my findings here.