LCD shows random characters (MPLAB) - c

Question

I'm trying to connect my LCD screen (16x02 QAPASS) to my PIC16F1937 on MPLAB, but it displays random characters (in this case Chinese characters, question marks and slash) instead of alphanumeric. However, all PIN connections have been declared in the library and correctly connected to the PIC. I use an XC8 compiler.
Here are the connections:
VSS --> GND
VDD --> 5V
VO --> 680Ω resistance
EN --> RD1
RW --> RD6
RS --> RD0
LCD_D4 --> RD2
LCD_D5 --> RD3
LCD_D6 --> RD4
LCD_D7 --> RD5
Anode --> 5V
Cathode --> GND
The global project is a sensor that detects the distance of an object and displays this same distance on the LCD. The fact that the LCD does not display the character compromises the rest of the project because I cannot set up the mathematical calculations if the LCD fails.
1) Library Code : lcd.h (Header Files) This is the code provided by Microchip for the LCD library and I added the PIN-LCD connections:
// single bit for selecting command register or data register
#define instr 0 #define data 1
// These #defines create the pin connections to the LCD in case they
are changed on a future demo board
#define LCD_PORT PORTD
#define LCD_PWR PORTDbits.RD7 // LCD power pin
#define LCD_EN PORTDbits.RD1 // LCD enable
#define LCD_RW PORTDbits.RD6 // LCD read/write line
#define LCD_RS PORTDbits.RD0
#define LCD_D4 PORTDbits.RD2
#define LCD_D5 PORTDbits.RD3
#define LCD_D6 PORTDbits.RD4
#define LCD_D7 PORTDbits.RD5
// LCD register select line
#define NB_LINES 2 // Number of display lines
#define NB_COL 16 // Number of
characters per line
2) Library Code 2 : lcd.c (Source Files) Contains the commands related to the LCD
3) Main Code : main.c (Source Files)
#include "mcc_generated_files/mcc.h"
#include "lcd.h"
#define _XTAL_FREQ 4000000
void main(void)
{
// initialize the device
SYSTEM_Initialize();
// initialize LCD
LCD_Initialize();
LCDGoto(4, 1); // go to column 4, row 1
LCDPutChar("test1");
LCDGoto(3, 2); // go to column 3, row 2
LCDPutStr("test2");
while (1)
{
}
}

Answer 1

#AfricaOMM,
It would appear that your code may be based on code from this link.
Because you posted only fragments it is impossible to determine just how bad the code you are trying to work from is.
The code at link I found has a Microchip copyright but it is of poor quality with bugs that will cause you several problems.
You would benefit in the long run by sorting out this mess on your own.
My best advise is to put LEDs on the signal lines that connect to your LCD module and verify that your PIC16F1937 sets each line to the correct state when the initialization code runs.
I suspect you have errors in wiring along with errors in your code.

Answer 2

Problem solved!
The problem was related to the library.
The library that Microchip provides is full of malfunctions, so when executing commands, the PIC do not receive the supposed informations it should receive, that's why the LCD shows random characters.
I suggest you use the library developed by electrosome : I confirm that it is 100% operational, thanks to them!
Another thing: to solve the contrast problem, it will ideally be necessary to connect the VO port of the LCD to a potentiometer.

Answer 3

When we send a msg on LCD it shows funny characters or some weird symbols because the hardware requires some time to get refreshed. You can try to give some sleep time.after this line
LCDPutStr("test2"). Put above sleep time
LCD.sleep(5)
It worked in my case.

Answer 4

When we send a msg on LCD it shows funny characters or some weird symbols because the hardware requires some time to get refreshed. You can try to give some sleep time.after this line
LCDPutStr("test2"). Put above sleep time
LCD.sleep(5)
It worked in my case. It worked in my case.