1. LCD Not Initializing
Q: My LCD shows nothing or random characters.
A:
- Verify
LCD_Init()was called first - Check power supply (4.7V-5.5V recommended)
- Confirm contrast potentiometer is adjusted
- For I2C LCDs: Ensure correct I2C address
2. Missing Characters/Garbled Text
Q: Some characters don’t display or appear corrupted.
A:
- Check all data connections (D4-D7 for 4-bit mode)
- Add 100ms delay after
LCD_Command(LCD_CLEAR) - Verify RS and EN signal timing
3. Cursor Position Issues
Q: Text appears at wrong locations.
A:
- Use
LCD_Goto(row,col)before writing - Row 1 = 0x80-0x8F, Row 2 = 0xC0-0xCF
- Clear display first if positioning fails
4. I2C LCD Specific Problems
Q: I2C LCD doesn’t respond.
A:
- Verify I2C address with scanner
- Check PCF8574 backpack connections
- Add pull-up resistors (4.7kΩ) on SDA/SCL
5. Display Flickering
Q: LCD flickers or shows unstable content.
A:
- Increase delay after EN pulse (try 200μs)
- Add 100μF capacitor across power pins
- Check for loose connections
6. Custom Character Creation
Q: How to display custom symbols?
A:
1 2 3 4 5 6 | // Define custom character (8x5 pattern) u8 heart[8] = {0x00,0x0A,0x1F,0x1F,0x0E,0x04,0x00,0x00}; LCD_Command(0x40); // CGRAM address for(u8 i=0; i<8; i++) LCD_Data(heart[i]); LCD_Goto(1,0); LCD_Data(0); // Display custom char 0 |
7. Power Saving Tips
Q: How to reduce LCD power consumption?
A:
- Use
LCD_Command(0x08)to turn off display - Lower VCC to 4.7V (minimum operational voltage)
- Disable backlight when not needed
8. Common Initialization Sequence
Q: What’s the proper startup sequence?
A:
1 2 3 4 5 6 | LCD_Init(); // Required first LCD_Command(0x28); // 4-bit, 2-line, 5x8 LCD_Command(0x0C); // Display ON, cursor OFF LCD_Command(0x01); // Clear display DelayMs(2); // Mandatory after clear LCD_Command(0x06); // Entry mode set |
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