Hi, as I mentioned in the title I am trying to set up a simple little Arduino touch screen. I should also note that I am very new to Arduino and that I am currently using a 12V power source, a 4 relays shield and a slightly complicated board (I'll link them below). These devices are mainly because I want to expand on this project later on, but for now I am just trying to get my touchscreen to run a simple button program (I'll link this as well).
Currently my issue is that when I run the button program, whilst my board is connected to my laptop (via a USBC port) everything seems to be working just fine, but when I change the power source to the 12V, the screen will display but it won't register any touches.
I have also tried running a calibrate screen demo program (again I will link this), which does seem to work on both power sources, although I cannot figure out what the button program does differently.
Besides from that I've run a whole bunch of other small tests, and the only thing I've found so far that might be making a difference is that when my board is connected to the 12V power source, my board is getting about 5V. But when it's connected to my laptop it's getting about 3.3V, although the screen is supposed to be compatible with both.
Could someone please advise what I should do, or even just tell me whether this an electrical issue or a code issue? This is my first time using an Arduino touch screen so it's probably my code, but I tried my best to stay simple and similar to demo code that I found.
Also, (I don't know how important this is) but all of my equipment is pretty much new and I think my laptop has a 65W (20V and 3.25A) output.
Touchscreen: http://www.lcdwiki.com/2.8inch_Arduino_Display
4 Relays Shield: Arduino 4 Relays Shield — Arduino Official Store
Board (very similar to a mega): https://wiki.keyestudio.com/KS5014_Keyestudio_2560_WIFI_PLUS_Main_Board
Simple Button Code:
#include <Adafruit_GFX.h>
#include <MCUFRIEND_kbv.h>
MCUFRIEND_kbv tft;
#include <TouchScreen.h>
#define MINPRESSURE 200
#define MAXPRESSURE 1000
// copy-paste results from the touchscreen calibration program
const int XP=8,XM=A2,YP=A3,YM=9; //240x320 ID=0x7575
const int TS_LEFT=933,TS_RT=101,TS_TOP=129,TS_BOT=913;
TouchScreen ts = TouchScreen(XP, YP, XM, YM, 300);
Adafruit_GFX_Button on_btn, off_btn;
int pixel_x, pixel_y;
bool Touch_getXY(void)
{
TSPoint p = ts.getPoint();
pinMode(YP, OUTPUT);
pinMode(XM, OUTPUT);
digitalWrite(YP, HIGH);
digitalWrite(XM, HIGH);
bool pressed = (p.z > MINPRESSURE && p.z < MAXPRESSURE);
if (pressed) {
pixel_x = map(p.x, TS_LEFT, TS_RT, 0, tft.width());
pixel_y = map(p.y, TS_TOP, TS_BOT, 0, tft.height());
}
return pressed;
}
#define BLACK 0x0000
#define BLUE 0x001F
#define RED 0xF800
#define GREEN 0x07E0
#define CYAN 0x07FF
#define MAGENTA 0xF81F
#define YELLOW 0xFFE0
#define WHITE 0xFFFF
void setup(void)
{
Serial.begin(9600);
uint16_t ID = tft.readID();
Serial.print("TFT ID = 0x");
Serial.println(ID, HEX);
Serial.println("Calibrate for your Touch Panel");
if (ID == 0xD3D3) ID = 0x9486; // write-only shield
tft.begin(ID);
tft.setRotation(0); //PORTRAIT
tft.fillScreen(BLACK);
on_btn.initButton(&tft, 60, 200, 100, 40, WHITE, CYAN, BLACK, "ON", 2);
off_btn.initButton(&tft, 180, 200, 100, 40, WHITE, CYAN, BLACK, "OFF", 2);
on_btn.drawButton(false);
off_btn.drawButton(false);
tft.fillRect(40, 80, 160, 80, RED);
}
void loop(void)
{
bool down = Touch_getXY();
Serial.print("Touch X: ");
Serial.print(pixel_x);
Serial.print(" Y: ");
Serial.println(pixel_y);
on_btn.press(down && on_btn.contains(pixel_x, pixel_y));
off_btn.press(down && off_btn.contains(pixel_x, pixel_y));
if (on_btn.justReleased())
on_btn.drawButton();
if (off_btn.justReleased())
off_btn.drawButton();
if (on_btn.justPressed()) {
on_btn.drawButton(true);
tft.fillRect(40, 80, 160, 80, GREEN);
}
if (off_btn.justPressed()) {
off_btn.drawButton(true);
tft.fillRect(40, 80, 160, 80, RED);
}
}
Calibrate screen code (this is only a snippet):
#define PORTRAIT 0
#define LANDSCAPE 1
#define USE_XPT2046 0
#define USE_LOCAL_KBV 1
#define TOUCH_ORIENTATION PORTRAIT
#if defined(USB_PID) && USB_PID == 0x804E // Arduino M0 Native
#define Serial SerialUSB
#endif
#define SWAP(x, y) { int t = x; x = y; y = t; }
#define TITLE "TouchScreen.h GFX Calibration"
#include <Adafruit_GFX.h>
#include <MCUFRIEND_kbv.h>
MCUFRIEND_kbv tft;
// MCUFRIEND UNO shield shares pins with the TFT.
#if defined(ESP32)
int XP = 27, YP = 4, XM = 15, YM = 14; //most common configuration
#else
//int XP = 6, YP = A1, XM = A2, YM = 7; //most common configuration
int XP = 7, YP = A2, XM = A1, YM = 6; //next common configuration
//int XP=PB7,XM=PA6,YP=PA7,YM=PB6; //BLUEPILL must have Analog for YP, XM
#endif
#if USE_LOCAL_KBV
#include "TouchScreen_kbv.h" //my hacked version
#define TouchScreen TouchScreen_kbv
#define TSPoint TSPoint_kbv
#else
#include <TouchScreen.h> //Adafruit Library
#endif
TouchScreen ts(XP, YP, XM, YM, 300); //re-initialised after diagnose
TSPoint tp; //global point
void readResistiveTouch(void)
{
tp = ts.getPoint();
pinMode(YP, OUTPUT); //restore shared pins
pinMode(XM, OUTPUT);
//digitalWrite(YP, HIGH); //because TFT control pins
//digitalWrite(XM, HIGH);
// Serial.println("tp.x=" + String(tp.x) + ", tp.y=" + String(tp.y) + ", tp.z =" + String(tp.z));
}
uint16_t readID(void) {
uint16_t ID = tft.readID();
if (ID == 0xD3D3) ID = 0x9486;
return ID;
}
#define TFT_BEGIN() tft.begin(ID)
#define WHITE 0xFFFF
#define RED 0xF800
#define BLUE 0x001F
#define GREEN 0x07E0
#define BLACK 0x0000
//#define GRAY 0x2408 //un-highlighted cross-hair
#define GRAY BLUE //idle cross-hair colour
#define GRAY_DONE RED //finished cross-hair
bool ISPRESSED(void)
{
// .kbv this was too sensitive !!
// now touch has to be stable for 50ms
int count = 0;
bool state, oldstate;
while (count < 10) {
readResistiveTouch();
state = tp.z > 200; //ADJUST THIS VALUE TO SUIT YOUR SCREEN e.g. 20 ... 250
if (state == oldstate) count++;
else count = 0;
oldstate = state;
delay(5);
}
return oldstate;
}
.
.
.
void startup()
{
centertitle(TITLE);
tft.println(F("#define NUMSAMPLES 3 in Library\n"));
tft.println(F("Use a stylus or something"));
tft.println(F("similar to touch as close"));
tft.println(F("to the center of the WHITE"));
tft.println(F("crosshair. Keep holding"));
tft.println(F("until crosshair turns RED."));
tft.println(F("Repeat for all crosshairs.\n"));
tft.println(F("Report can be pasted from Serial\n"));
tft.println(F("Touch screen to continue"));
while (ISPRESSED() == false) {}
while (ISPRESSED() == true) {}
// waitForTouch();
}
I hope that's enough of the code to be useful. Thanks in advance 
