ST7920 and Mega are not playing nice

kuillemaul · May 2, 2021, 12:33pm

I have been trying to figure out why the ST7920 LC screen refuses to work with my MEGA. I have 2 UNO's and they work perfectly. I have use the same code on both UNO's and my MEGA however the MEGA fails to work. At all. Gets power but does not display anything.

I am using the exact same pins on all 3 boards.

Here is the code I am using. It is just the basic example. Any idea why the MEGA just wont have a bar of it?

#include "U8glib.h"
U8GLIB_ST7920_128X64_4X u8g(10);
// setup u8g object, please remove comment from one of the following constructor calls
// IMPORTANT NOTE: The following list is incomplete. The complete list of supported 
// devices with all constructor calls is here: https://github.com/olikraus/u8glib/wiki/device
//U8GLIB_NHD27OLED_BW u8g(13, 11, 10, 9);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_NHD27OLED_2X_BW u8g(13, 11, 10, 9);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_NHD27OLED_GR u8g(13, 11, 10, 9);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_NHD27OLED_2X_GR u8g(13, 11, 10, 9);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_NHD31OLED_BW u8g(13, 11, 10, 9);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_NHD31OLED_2X_BW u8g(13, 11, 10, 9);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_NHD31OLED_GR u8g(13, 11, 10, 9);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_NHD31OLED_2X_GR u8g(13, 11, 10, 9);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_DOGS102 u8g(13, 11, 10, 9, 8);		// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_DOGM132 u8g(13, 11, 10, 9);		// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_DOGM128 u8g(13, 11, 10, 9);		// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_DOGM128_2X u8g(13, 11, 10, 9);		// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_ST7920_128X64_1X u8g(8, 9, 10, 11, 4, 5, 6, 7, 18, 17, 16);   // 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7 en=18, di=17,rw=16
//U8GLIB_ST7920_128X64_4X u8g(8, 9, 10, 11, 4, 5, 6, 7, 18, 17, 16);   // 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7 en=18, di=17,rw=16
//U8GLIB_ST7920_128X64_1X u8g(18, 16, 17);	// SPI Com: SCK = en = 18, MOSI = rw = 16, CS = di = 17
//U8GLIB_ST7920_128X64_4X u8g(18, 16, 17);	// SPI Com: SCK = en = 18, MOSI = rw = 16, CS = di = 17
//U8GLIB_ST7920_192X32_1X u8g(8, 9, 10, 11, 4, 5, 6, 7, 18, 17, 16);   // 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7 en=18, di=17,rw=16
//U8GLIB_ST7920_192X32_4X u8g(8, 9, 10, 11, 4, 5, 6, 7, 18, 17, 16);   // 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7 en=18, di=17,rw=16
//U8GLIB_ST7920_192X32_1X u8g(18, 16, 17);	// SPI Com: SCK = en = 18, MOSI = rw = 16, CS = di = 17
//U8GLIB_ST7920_192X32_4X u8g(18, 16, 17);	// SPI Com: SCK = en = 18, MOSI = rw = 16, CS = di = 17
//U8GLIB_ST7920_192X32_1X u8g(13, 11, 10);	// SPI Com: SCK = en = 13, MOSI = rw = 11, CS = di = 10
//U8GLIB_ST7920_192X32_4X u8g(10);		// SPI Com: SCK = en = 13, MOSI = rw = 11, CS = di = 10, HW SPI
//U8GLIB_ST7920_202X32_1X u8g(8, 9, 10, 11, 4, 5, 6, 7, 18, 17, 16);   // 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7 en=18, di=17,rw=16
//U8GLIB_ST7920_202X32_4X u8g(8, 9, 10, 11, 4, 5, 6, 7, 18, 17, 16);   // 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7 en=18, di=17,rw=16
//U8GLIB_ST7920_202X32_1X u8g(18, 16, 17);	// SPI Com: SCK = en = 18, MOSI = rw = 16, CS = di = 17
//U8GLIB_ST7920_202X32_4X u8g(18, 16, 17);	// SPI Com: SCK = en = 18, MOSI = rw = 16, CS = di = 17
//U8GLIB_LM6059 u8g(13, 11, 10, 9);		// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_LM6063 u8g(13, 11, 10, 9);		// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_DOGXL160_BW u8g(10, 9);		// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_DOGXL160_GR u8g(13, 11, 10, 9);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_DOGXL160_2X_BW u8g(13, 11, 10, 9);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_DOGXL160_2X_GR u8g(13, 11, 10, 9);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_PCD8544 u8g(13, 11, 10, 9, 8);		// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9, Reset = 8
//U8GLIB_PCF8812 u8g(13, 11, 10, 9, 8);		// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9, Reset = 8
//U8GLIB_KS0108_128 u8g(8, 9, 10, 11, 4, 5, 6, 7, 18, 14, 15, 17, 16); 		// 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7 en=18, cs1=14, cs2=15,di=17,rw=16
//U8GLIB_LC7981_160X80 u8g(8, 9, 10, 11, 4, 5, 6, 7,  18, 14, 15, 17, 16); 	// 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7 en=18, cs=14 ,di=15,rw=17, reset = 16
//U8GLIB_LC7981_240X64 u8g(8, 9, 10, 11, 4, 5, 6, 7,  18, 14, 15, 17, 16); 	// 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7 en=18, cs=14 ,di=15,rw=17, reset = 16
//U8GLIB_LC7981_240X128 u8g(8, 9, 10, 11, 4, 5, 6, 7,  18, 14, 15, 17, 16); 	// 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7 en=18, cs=14 ,di=15,rw=17, reset = 16
//U8GLIB_ILI9325D_320x240 u8g(18,17,19,U8G_PIN_NONE,16 );  			// 8Bit Com: D0..D7: 0,1,2,3,4,5,6,7 en=wr=18, cs=17, rs=19, rd=U8G_PIN_NONE, reset = 16
//U8GLIB_SBN1661_122X32 u8g(8,9,10,11,4,5,6,7,14,15, 17, U8G_PIN_NONE, 16); 	// 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7 cs1=14, cs2=15,di=17,rw=16,reset = 16
//U8GLIB_SSD1306_128X64 u8g(13, 11, 10, 9, 8);	// SW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_SSD1306_128X64 u8g(4, 5, 6, 7);	// SW SPI Com: SCK = 4, MOSI = 5, CS = 6, A0 = 7 (new white HalTec OLED)
//U8GLIB_SSD1306_128X64 u8g(10, 9);		// HW SPI Com: CS = 10, A0 = 9 (Hardware Pins are  SCK = 13 and MOSI = 11)
//U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_NONE|U8G_I2C_OPT_DEV_0);	// I2C / TWI 
//U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_DEV_0|U8G_I2C_OPT_NO_ACK|U8G_I2C_OPT_FAST);	// Fast I2C / TWI 
//U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_NO_ACK);	// Display which does not send AC
//U8GLIB_SSD1306_ADAFRUIT_128X64 u8g(13, 11, 10, 9);	// SW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_SSD1306_ADAFRUIT_128X64 u8g(10, 9);		// HW SPI Com: CS = 10, A0 = 9 (Hardware Pins are  SCK = 13 and MOSI = 11)
//U8GLIB_SSD1306_128X32 u8g(13, 11, 10, 9);	// SW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_SSD1306_128X32 u8g(10, 9);             // HW SPI Com: CS = 10, A0 = 9 (Hardware Pins are  SCK = 13 and MOSI = 11)
//U8GLIB_SSD1306_128X32 u8g(U8G_I2C_OPT_NONE);	// I2C / TWI 
//U8GLIB_SSD1306_64X48 u8g(13, 11, 10, 9);	// SW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_SSD1306_64X48 u8g(10, 9);             // HW SPI Com: CS = 10, A0 = 9 (Hardware Pins are  SCK = 13 and MOSI = 11)
//U8GLIB_SSD1306_64X48 u8g(U8G_I2C_OPT_NONE);	// I2C / TWI 
//U8GLIB_SH1106_128X64 u8g(13, 11, 10, 9);	// SW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_SH1106_128X64 u8g(4, 5, 6, 7);	// SW SPI Com: SCK = 4, MOSI = 5, CS = 6, A0 = 7 (new blue HalTec OLED)
//U8GLIB_SH1106_128X64 u8g(U8G_I2C_OPT_NONE);	// I2C / TWI 
//U8GLIB_SH1106_128X64 u8g(U8G_I2C_OPT_DEV_0|U8G_I2C_OPT_FAST);	// Dev 0, Fast I2C / TWI
//U8GLIB_SH1106_128X64 u8g(U8G_I2C_OPT_NO_ACK);	// Display which does not send ACK
//U8GLIB_SSD1309_128X64 u8g(13, 11, 10, 9);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_SSD1327_96X96_GR u8g(U8G_I2C_OPT_NONE);	// I2C
//U8GLIB_SSD1327_96X96_2X_GR u8g(U8G_I2C_OPT_NONE);	// I2C
//U8GLIB_UC1611_DOGM240 u8g(U8G_I2C_OPT_NONE);	// I2C
//U8GLIB_UC1611_DOGM240 u8g(13, 11, 10, 9);	// SW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_UC1611_DOGM240 u8g(10, 9);		// HW SPI Com: CS = 10, A0 = 9 (Hardware Pins are  SCK = 13 and MOSI = 11)
//U8GLIB_UC1611_DOGM240 u8g(10, 9);		// HW SPI Com: CS = 10, A0 = 9 (Hardware Pins are  SCK = 13 and MOSI = 11)
//U8GLIB_UC1611_DOGM240 u8g(8, 9, 10, 11, 4, 5, 6, 7, 18, 3, 17, 16);   // 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7 en=18, cs=3, di/a0=17,rw=16
//U8GLIB_UC1611_DOGXL240 u8g(U8G_I2C_OPT_NONE);	// I2C
//U8GLIB_UC1611_DOGXL240 u8g(13, 11, 10, 9);	// SW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
//U8GLIB_UC1611_DOGXL240 u8g(10, 9);		// HW SPI Com: CS = 10, A0 = 9 (Hardware Pins are  SCK = 13 and MOSI = 11)
//U8GLIB_UC1611_DOGXL240 u8g(8, 9, 10, 11, 4, 5, 6, 7, 18, 3, 17, 16);   // 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7 en=18, cs=3, di/a0=17,rw=16
//U8GLIB_NHD_C12864 u8g(13, 11, 10, 9, 8);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9, RST = 8
//U8GLIB_NHD_C12832 u8g(13, 11, 10, 9, 8);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9, RST = 8
//U8GLIB_LD7032_60x32 u8g(13, 11, 10, 9, 8);	// SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9, RST = 8
//U8GLIB_LD7032_60x32 u8g(11, 12, 9, 10, 8);	// SPI Com: SCK = 11, MOSI = 12, CS = 9, A0 = 10, RST = 8  (SW SPI Nano Board)
//U8GLIB_UC1608_240X64 u8g(13, 11, 10, 9, 8);	// SW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9, RST = 8
//U8GLIB_UC1608_240X64_2X u8g(13, 11, 10, 9, 8);	// SW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9, RST = 8
//U8GLIB_UC1608_240X64 u8g(10, 9, 8);	// HW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9, RST = 8
//U8GLIB_UC1608_240X64_2X u8g(10, 9, 8);	// HW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9, RST = 8
//U8GLIB_UC1608_240X u8g(13, 11, 10, 9, 8);	// SW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9, RST = 8
//U8GLIB_UC1608_240X64_2X u8g(13, 11, 10, 9, 8);	// SW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9, RST = 8
//U8GLIB_UC1608_240X64 u8g(10, 9, 8);	// HW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9, RST = 8
//U8GLIB_UC1608_240X64_2X u8g(10, 9, 8);	// HW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9, RST = 8
//U8GLIB_T6963_240X128 u8g(8, 9, 10, 11, 4, 5, 6, 7, 14, 15, 17, 18, 16); // 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7, cs=14, a0=15, wr=17, rd=18, reset=16
//U8GLIB_T6963_128X128 u8g(8, 9, 10, 11, 4, 5, 6, 7, 14, 15, 17, 18, 16); // 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7, cs=14, a0=15, wr=17, rd=18, reset=16
//U8GLIB_T6963_240X64 u8g(8, 9, 10, 11, 4, 5, 6, 7, 14, 15, 17, 18, 16); // 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7, cs=14, a0=15, wr=17, rd=18, reset=16
//U8GLIB_T6963_128X64 u8g(8, 9, 10, 11, 4, 5, 6, 7, 14, 15, 17, 18, 16); // 8Bit Com: D0..D7: 8,9,10,11,4,5,6,7, cs=14, a0=15, wr=17, rd=18, reset=16
//U8GLIB_HT1632_24X16 u8g(3, 2, 4);		// WR = 3, DATA = 2, CS = 4
//U8GLIB_SSD1351_128X128_332 u8g(13, 11, 8, 9, 7); // Arduino UNO: SW SPI Com: SCK = 13, MOSI = 11, CS = 8, A0 = 9, RESET = 7 (http://electronics.ilsoft.co.uk/ArduinoShield.aspx)
//U8GLIB_SSD1351_128X128_332 u8g(76, 75, 8, 9, 7); // Arduino DUE: SW SPI Com: SCK = 13, MOSI = 11, CS = 8, A0 = 9, RESET = 7 (http://electronics.ilsoft.co.uk/ArduinoShield.aspx)
//U8GLIB_SSD1351_128X128_332 u8g(8, 9, 7); // Arduino: HW SPI Com: SCK = 13, MOSI = 11, CS = 8, A0 = 9, RESET = 7 (http://electronics.ilsoft.co.uk/ArduinoShield.aspx)
//U8GLIB_SSD1351_128X128_HICOLOR u8g(76, 75, 8, 9, 7); // Arduino DUE, SW SPI Com: SCK = 76, MOSI = 75, CS = 8, A0 = 9, RESET = 7 (http://electronics.ilsoft.co.uk/ArduinoShield.aspx)
//U8GLIB_SSD1351_128X128_HICOLOR u8g(8, 9, 7); // Arduino, HW SPI Com: SCK = 76, MOSI = 75, CS = 8, A0 = 9, RESET = 7 (http://electronics.ilsoft.co.uk/ArduinoShield.aspx)
//U8GLIB_SSD1351_128X128GH_332 u8g(8, 9, 7); // Arduino, HW SPI Com: SCK = 76, MOSI = 75, CS = 8, A0 = 9, RESET = 7 (Freetronics OLED)
//U8GLIB_SSD1351_128X128GH_HICOLOR u8g(8, 9, 7); // Arduino, HW SPI Com: SCK = 76, MOSI = 75, CS = 8, A0 = 9, RESET = 7 (Freetronics OLED)

void u8g_prepare(void) {
  u8g.setFont(u8g_font_6x10);
  u8g.setFontRefHeightExtendedText();
  u8g.setDefaultForegroundColor();
  u8g.setFontPosTop();
}

void u8g_box_frame(uint8_t a) {
  u8g.drawStr( 0, 0, "drawBox");
  u8g.drawBox(5,10,20,10);
  u8g.drawBox(10+a,15,30,7);
  u8g.drawStr( 0, 30, "drawFrame");
  u8g.drawFrame(5,10+30,20,10);
  u8g.drawFrame(10+a,15+30,30,7);
}

void u8g_disc_circle(uint8_t a) {
  u8g.drawStr( 0, 0, "drawDisc");
  u8g.drawDisc(10,18,9);
  u8g.drawDisc(24+a,16,7);
  u8g.drawStr( 0, 30, "drawCircle");
  u8g.drawCircle(10,18+30,9);
  u8g.drawCircle(24+a,16+30,7);
}

void u8g_r_frame(uint8_t a) {
  u8g.drawStr( 0, 0, "drawRFrame/Box");
  u8g.drawRFrame(5, 10,40,30, a+1);
  u8g.drawRBox(50, 10,25,40, a+1);
}

void u8g_string(uint8_t a) {
  u8g.drawStr(30+a,31, " 0");
  u8g.drawStr90(30,31+a, " 90");
  u8g.drawStr180(30-a,31, " 180");
  u8g.drawStr270(30,31-a, " 270");
}

void u8g_line(uint8_t a) {
  u8g.drawStr( 0, 0, "drawLine");
  u8g.drawLine(7+a, 10, 40, 55);
  u8g.drawLine(7+a*2, 10, 60, 55);
  u8g.drawLine(7+a*3, 10, 80, 55);
  u8g.drawLine(7+a*4, 10, 100, 55);
}

void u8g_triangle(uint8_t a) {
  uint16_t offset = a;
  u8g.drawStr( 0, 0, "drawTriangle");
  u8g.drawTriangle(14,7, 45,30, 10,40);
  u8g.drawTriangle(14+offset,7-offset, 45+offset,30-offset, 57+offset,10-offset);
  u8g.drawTriangle(57+offset*2,10, 45+offset*2,30, 86+offset*2,53);
  u8g.drawTriangle(10+offset,40+offset, 45+offset,30+offset, 86+offset,53+offset);
}

void u8g_ascii_1() {
  char s[2] = " ";
  uint8_t x, y;
  u8g.drawStr( 0, 0, "ASCII page 1");
  for( y = 0; y < 6; y++ ) {
    for( x = 0; x < 16; x++ ) {
      s[0] = y*16 + x + 32;
      u8g.drawStr(x*7, y*10+10, s);
    }
  }
}

void u8g_ascii_2() {
  char s[2] = " ";
  uint8_t x, y;
  u8g.drawStr( 0, 0, "ASCII page 2");
  for( y = 0; y < 6; y++ ) {
    for( x = 0; x < 16; x++ ) {
      s[0] = y*16 + x + 160;
      u8g.drawStr(x*7, y*10+10, s);
    }
  }
}

void u8g_extra_page(uint8_t a)
{
  if ( u8g.getMode() == U8G_MODE_HICOLOR || u8g.getMode() == U8G_MODE_R3G3B2) {
    /* draw background (area is 128x128) */
    u8g_uint_t r, g, b;
    b = a << 5;
    for( g = 0; g < 64; g++ )
    {
      for( r = 0; r < 64; r++ )
      {
	u8g.setRGB(r<<2, g<<2, b );
	u8g.drawPixel(g, r);
      }
    }
    u8g.setRGB(255,255,255);
    u8g.drawStr( 66, 0, "Color Page");
  }
  else if ( u8g.getMode() == U8G_MODE_GRAY2BIT )
  {
    u8g.drawStr( 66, 0, "Gray Level");
    u8g.setColorIndex(1);
    u8g.drawBox(0, 4, 64, 32);    
    u8g.drawBox(70, 20, 4, 12);
    u8g.setColorIndex(2);
    u8g.drawBox(0+1*a, 4+1*a, 64-2*a, 32-2*a);
    u8g.drawBox(74, 20, 4, 12);
    u8g.setColorIndex(3);
    u8g.drawBox(0+2*a, 4+2*a, 64-4*a, 32-4*a);
    u8g.drawBox(78, 20, 4, 12);
  }
  else
  {
    u8g.drawStr( 0, 12, "setScale2x2");
    u8g.setScale2x2();
    u8g.drawStr( 0, 6+a, "setScale2x2");
    u8g.undoScale();
  }
}


uint8_t draw_state = 0;

void draw(void) {
  u8g_prepare();
  switch(draw_state >> 3) {
    case 0: u8g_box_frame(draw_state&7); break;
    case 1: u8g_disc_circle(draw_state&7); break;
    case 2: u8g_r_frame(draw_state&7); break;
    case 3: u8g_string(draw_state&7); break;
    case 4: u8g_line(draw_state&7); break;
    case 5: u8g_triangle(draw_state&7); break;
    case 6: u8g_ascii_1(); break;
    case 7: u8g_ascii_2(); break;
    case 8: u8g_extra_page(draw_state&7); break;
  }
}

void setup(void) {

  // flip screen, if required
  //u8g.setRot180();

#if defined(ARDUINO)
  pinMode(13, OUTPUT);           
  digitalWrite(13, HIGH);  
#endif
}

void loop(void) {
  
  // picture loop  
  u8g.firstPage();  
  do {
    draw();
  } while( u8g.nextPage() );
  
  // increase the state
  draw_state++;
  if ( draw_state >= 9*8 )
    draw_state = 0;
  
  // rebuild the picture after some delay
  //delay(150);

}

wildbill · May 2, 2021, 12:45pm

How do you have it wired up on the two different Arduinos?

kuillemaul · May 2, 2021, 12:50pm

I have use the same PIN config when trying on all boards. same as the image.
RS R/W and E on pin 10, 11, 13.

wildbill · May 2, 2021, 12:55pm

Looks like you're using SPI. Mega uses different pins - look: https://www.arduino.cc/en/reference/SPI

kuillemaul · May 2, 2021, 12:59pm

Thanks man you nailed. Why didn't I come across that in my search? Maybe not asking to right questions.

Thank again.

system · August 30, 2021, 1:00pm

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