Hello!
For my internship project I have to use the nhd-0420d3z-nsw-bbw-v3 20x4 LCD display to display pressure and temperature.
The display is connected via I2C with an Arduino uno.
When I run my code (still only displays press: and temp: while refreshing every 2 seconds) the words have a vertical line inbetween every character (picture included).
Has anybody experienced a problem like this or a solution?
Thanks!
#include <Wire.h>
#define LCD_I2C_ADDRESS 0x28
void setup() {
Wire.begin();
pinMode(A4, INPUT_PULLUP);
pinMode(A5, INPUT_PULLUP);
delay(200); // Wait for the LCD to initialize (at least 100ms according to the datasheet)
sendCommand(0xFE, 0x41); // Turn on display
setBrightness();
delay(100);
clearScreen();
}
void loop() {
// Set cursor position to the beginning of the second line (row 1)
// Display "Hello, World!" on the LCD
displayText("Press: ", 0x00);
displayText("Temp: ", 0x40);
delay(2000); // Wait for 2 seconds
clearScreen(); // Clear the screen for the next message
delay(1000); // Wait for 1 second before repeating the loop
}
void sendCommand(byte prefix, byte command) {
Wire.beginTransmission(LCD_I2C_ADDRESS);
Wire.write(prefix);
Wire.write(command);
Wire.endTransmission();
delay(1); // Delay to ensure commands are processed properly
}
void setCursor(byte pos) {
sendCommand(0xFE, 0x45); // Set cursor command
delayMicroseconds(100);
sendCommand(pos, 0x00); // Set cursor position
delayMicroseconds(100);
}
void clearScreen() {
sendCommand(0xFE, 0x51); // Clear screen command
delay(1500); // Wait for the screen to clear
}
void displayText(const char *text, byte pos) {
setCursor(pos); // Set cursor position
while (*text) {
sendCommand(0x00, *text); // Display character command
delayMicroseconds(100); // Wait for the character to be written (adjust delay if necessary)
text++;
}
}
void setBrightness() {
sendCommand(0xFE, 0x53);
sendCommand(0x08, 0x00);
}
Where did you get this from? There are no commands starting from 0x00 in the datasheet.
The cause of the error is because your code for displaying text is incorrect. . No commands are needed to display characters. You just send character after character, that's all. See the example linked in the datasheet on page 14.
Printing the text "Serial LCD Demo" at the cursor position 0x40:
lcd_cursor(0x40);
delay_ms(100);
for (i = 0; i < 16; i++) { //"Serial LCD Demo"
tx_packet[i] = text7[i];
}
send_packet(16);
As you can see, the text transferred char by char without any commands between it.
You can just to copy the procedures lcd_cursor() and send_packet() to your code.
Stage\Arduino\LCD_press_test\LCD_press_test.ino: In function 'void loop()':
Stage\Arduino\LCD_press_test\LCD_press_test.ino:17:3: error: 'lcd_cursor' was not declared in this scope
lcd_cursor(0x40);
^~~~~~~~~~
Stage\Arduino\LCD_press_test\LCD_press_test.ino:17:3: note: suggested alternative: 'setCursor'
lcd_cursor(0x40);
^~~~~~~~~~
setCursor
Stage\Arduino\LCD_press_test\LCD_press_test.ino:18:3: error: 'delay_ms' was not declared in this scope
delay_ms(100);
^~~~~~~~
Stage\Arduino\LCD_press_test\LCD_press_test.ino:18:3: note: suggested alternative: '_delay_ms'
delay_ms(100);
^~~~~~~~
_delay_ms
Stage\Arduino\LCD_press_test\LCD_press_test.ino:20:10: error: 'i' was not declared in this scope
for (i = 0; i < 16; i++) { //"Serial LCD Demo"
^
Stage\Arduino\LCD_press_test\LCD_press_test.ino:21:7: error: 'tx_packet' was not declared in this scope
tx_packet[i] = text7[i];
^~~~~~~~~
Stage\Arduino\LCD_press_test\LCD_press_test.ino:21:22: error: 'text7' was not declared in this scope
tx_packet[i] = text7[i];
^~~~~
Stage\Arduino\LCD_press_test\LCD_press_test.ino:24:3: error: 'send_packet' was not declared in this scope
send_packet(16);
^~~~~~~~~~~
exit status 1
Compilation error: 'lcd_cursor' was not declared in this scope
Hmm looks difficult but I'll give it a try.
The thing which I don't understand is, why would the lcd screen still print these characters in the original code, just in a weird way
Of course, you must declare all variables, create all the specified procedures and data structures in your code.
But you always have to do this when you add someone else’s code to your program; Arduino has nothing to do with it.
Because the display treated 0x00 as a character and printed it between other letters. Codes from 0x00 to 0x07 are reserved for special characters that can be changed. Apparently under code 0x00 you have a symbol "||"
