Re: OLED Display Noise problem
Usually issues with junk appearing in the display have to do with not allowing the LCD time to process commands.
If you want to hammer the display as fast as possible then you might try reading the BUSY status flag between operations.
Try this and see if it gets any better (untested, so beware)...
You might find that you need to split the cursor position commands and data...Code:'------------------------------------------------------------------------------- define OSC 4 OSCCON=%01101010 'OSC is @ 4 MHZ '------------- LCD DEFINES ------------------------ DEFINE LCD_DREG PORTB 'LCD data port DEFINE LCD_DBIT 4 'LCD data starting bit 0 or 4 DEFINE LCD_RSREG PORTA 'LCD register select port DEFINE LCD_RSBIT 7 'LCD register select bit DEFINE LCD_RWREG PORTA 'LCD read/write port DEFINE LCD_RWBIT 0 'LCD read/write pin bit DEFINE LCD_EREG PORTA 'LCD enable port DEFINE LCD_EBIT 6 'LCD enable bit DEFINE LCD_BITS 4 'LCD bus size 4 or 8 DEFINE LCD_LINES 2 'Number lines on LCD DEFINE LCD_COMMANDUS 6200 'command delay time (in us) - clear display requires 6.2ms DEFINE LCD_DATAUS 50 'data delay time (in us) '------------------------------------------------------------------------------- PORTA = %00000000 PORTB = %00000000 TRISA = %00000000 TRISB = %00000000 ANSELA = %00000 ANSELB = %00000000 'ADCON0=%00000001 'ADCON1=%10110000 'OPTION_REG.7=0 '------------------------------------------------------------------------------- pause 500 'wait for display powerup lcdout $FE,$28 'function set 4-bit mode call lcd_busy_wait lcdout $FE,$08 'display off call lcd_busy_wait lcdout $FE,$06 'entry mode set call lcd_busy_wait lcdout $FE,$17 'char mode + internal power call lcd_busy_wait lcdout $FE,$01 'clear display (requires long delay) call lcd_busy_wait lcdout $FE,$02 'home call lcd_busy_wait lcdout $FE,$0C 'display on MAIN: call lcd_busy_wait lcdout $FE,$80,"BU BiR DENEMEDiR" call lcd_busy_wait lcdout $FE,$C0," iKiNCi SATIR " goto main 'sub lcd_busy_wait 'read lcd busy flag until busy=0 WAITST CON 1 ' delay 1us busy var bit lcd_busy_wait: busy = 1 TRISB = TRISB or $F0 'set PORTB D4-D7 to inputs @ bcf LCD_RSREG, LCD_RSBIT 'RS=0 @ bsf LCD_RWREG, LCD_RWBIT 'RW=1 pauseus WAITST 'wait for lcd busy flag (D7) to be low do while (busy = 1) @ bsf LCD_EREG, LCD_EBIT 'EN=1 pauseus WAITST busy = PORTB.7 'read busy bit (bit 7 in upper nibble) @ bcf LCD_EREG, LCD_EBIT 'EN=0 pauseus WAITST ' dummy read of lower nibble @ bsf LCD_EREG, LCD_EBIT 'EN=1 pauseus WAITST @ bcf LCD_EREG, LCD_EBIT 'EN=0 pauseus WAITST loop TRISB = TRISB and not $F0 'set PORTB D4-D7 back to outputs @ bcf LCD_RWREG, LCD_RWBIT 'RW=0 return
Even with doing things like this some displays just don't like being continuously written to and you need to use delays.Code:call lcd_busy_wait lcdout $FE,$80 'move cursor call lcd_busy_wait lcdout "BU BiR DENEMEDiR" 'send data
Reading the BUSY flag really needs to be done for each byte transferred, so it may not help much at all.
Originally Posted by tumbleweed
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