Using 16F1503 as Serial LCD Backpack
Hi All,
Wow, it has been awhile since I've been here. Finally getting back into PIC's and I'm making a serial backpack using a 16F1503. I've managed to make one successfully in 4-bit mode using RC0-3 connected to LCD pins DB4-7. Being a glutton for punishment, I'm now trying to make a backpack for those nifty RGB character LCD's. To do this, I've attempting to use RA0-3 connected to DB4-7 because I need the PWM pins free on the C port. The problem is, the PIC doesn't seem to communicate to the LCD when I do this.
I've checked my connections and code multiple times and I've been reviewing the datasheet (did discover I hadn't disabled the comparators or DAC - fixed this, but still no dice). I'm having the code step through a few different colors on the LCD, so I can see the colors change and confirm that portion is working. The top line (2 x 16) will appear filled with blocks before the bottom one as I adjust the contrast to one extreme. I take this to mean the LCD thinks it is in one-line mode so no communication between the PIC and LCD.
I did connect the LCD to my original backpack circuit where RC0-3 is connected to data lines and the LCD works fine - text is displayed. The problem seems to be using RA0-3 to communicate to the data lines.
Anyone happen to use RA0-3 on a 16F1503 to communicate with an LCD in 4-bit mode? Am I missing a config or register setting somewhere?
RA0 connected to DB4
RA1 connected to DB5
RA2 connected to DB6
RA3 connected to DB7
RC0 connected to Register Select
RC2 connected to Enable
R/W connected to GND
Code:#CONFIG __config _CONFIG1, _FOSC_INTOSC & _MCLRE_OFF & _CP_ON & _CLKOUTEN_OFF __config _CONFIG2, _LVP_OFF & _LPBOR_OFF #ENDCONFIG DEFINE OSC 16 ' Let PBP clock speed will be 16MHz OSCCON = $7B ' Use internal oscillator and set to 16MHz DEFINE LCD_DREG PORTA ' Use Port A for LCD data DEFINE LCD_DBIT 0 ' Use RA0-RA3 for LCD data DEFINE LCD_RSREG PORTC ' Use Port C for register select connection to LCD DEFINE LCD_RSBIT 0 ' Use RC0 for register select connection to LCD DEFINE LCD_EREG PORTC ' Use Port C for enable connection to LCD DEFINE LCD_EBIT 2 ' Use RC2 for enable connection to LCD DEFINE LCD_BITS 4 ' Use 4-bit bus to communicate with LCD DEFINE LCD_LINES 2 ' Set number of lines on LCD to two (or more) DEFINE LCD_COMMANDUS 1500 ' Set LCD command delay time to 1500us DEFINE LCD_DATAUS 44 ' Set LCD data delay time to 44us DEFINE SER2_BITS 8 ' Set serin2 command as 8 bits, no parity OPTION_REG.7 = 0 ' Enable individual control of weak pull-ups WPUA.0 = 0 ' Disable weak pull-up on RA0 WPUA.1 = 0 ' Disable weak pull-up on RA1 WPUA.2 = 0 ' Disable weak pull-up on RA2 WPUA.3 = 0 ' Disable weak pull-up on RA3 WPUA.4 = 1 ' Enable weak pull-up on RA4 WPUA.5 = 1 ' Enable weak pull-up on RA5 ANSELA = $00 ' Set all ADC pins as digital only ANSELC = $00 ' Set all ADC pins as digital only ADCON0 = $00 ' Disable all ADC's DACCON0.7 = 0 ' Disable DAC CM1CON0.7 = 0 ' Disable comparator 1 CM2CON0.7 = 0 ' Disable comparator 2 TRISA = %00110000 ' Set RA0-RA3 as outputs and RA4-RA5 as inputs TRISC = %00010000 ' Set RC0-RC3 & RC5 as outputs and RC4 as an input baud VAR WORD ' Word-sized variable used to set baud rate of serial communication baud = 0 ' Clear baud value to zero baud_display VAR WORD ' Word-sized variable to show actual baud rate selected baud_display = 0 ' Clear baud_display variable to zero duty_cycle VAR Byte ' Byte-sized variable used to set PWM duty cycle LED VAR BYTE ' Byte-sized variable used to define which LED to control PWM_freq VAR WORD ' Word-sized variable used to set PWM frequency PWM_freq = 1000 ' Set PWM frequency equal to 1kHz data_in VAR BYTE[2] ' Byte-sized variable used to store incoming data RED VAR PORTC.5 ' Define pin RC5 as RED (LED) GREEN VAR PORTC.3 ' Define pin RC3 as GREEN (LED) BLUE VAR PORTC.1 ' Define pin RC1 as BLUE (LED) RX VAR PORTC.4 ' Define pin RC4 as RX PAUSE 500 ' Wait 500ms for LCD to initialize '**************************************************************** Initialize: ' Read switch inputs to determine baud rate IF PORTA.4 = 0 THEN ' If switch position one is low, then IF PORTA.5 = 0 THEN ' If switch position two is also low, then baud = 396 ' Set baud rate to 2400 baud_display = 2400 ' Set baud display to 2400 ELSE ' If switch position one is low and switch position two is high, then baud = 188 ' Set baud rate to 4800 baud_display = 4800 ' Set baud display to 4800 ENDIF ' End second if statement ELSE ' Otherwise assume switch position one is high and IF PORTA.5 = 0 THEN ' If switch one is high and switch two is low, then baud = 84 ' Set baud rate to 9600 baud_display = 9600 ' Set baud display to 9600 ELSE ' If switch one is high and switch two is high, then baud = 32 ' Set baud rate to 19200 baud_display = 19200 ' Set baud display to 19200 ENDIF ' End second if statement ENDIF ' End first if statement HIGH RED ' Turn on red LED backlight LOW GREEN ' Turn off green LED backlight LOW BLUE ' Turn off blue LED backlight LCDOUT $FE, $01 ' Clear LCD PAUSE 30 ' Wait 30ms to allow screen to clear LCDOUT $FE, $80, "Test line 1" ' Display message at beginning of first line of LCD LCDOUT $FE, $C0, "Test line 2" ' Display message at beginning of second line of LCD PAUSE 1000 ' Wait 1 second LOW RED ' Turn off red LED backlight HIGH GREEN ' Turn on green LED backlight PAUSE 1000 ' Wait 1 second LOW GREEN ' Turn off green LED backlight HIGH BLUE ' Turn on blue LED backlight PAUSE 1000 ' Wait 1 second HIGH RED ' Turn on red LED backlight PAUSE 1000 ' Wait 1 second LOW BLUE ' Turn off blue LED backlight HIGH GREEN ' Turn on green LED backlight PAUSE 1000 ' Wait 1 second LOW RED ' Turn off red LED backlight HIGH BLUE ' Turn on blue LED backlight PAUSE 1000 ' Wait 1 second HIGH RED ' Turn on red LED backlight PAUSE 1000 ' Wait 1 second LOW RED ' Turn off red LED backlight LOW BLUE ' Turn off blue LED backlight LCDOUT $FE, $01 ' Clear LCD PAUSE 30 ' Wait 30ms to allow screen to clear
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