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
Re: Using 16F1503 as Serial LCD Backpack
Doh, I think I figured it out. Looks like RA3 can only be configured as an input. :o
Re: Using 16F1503 as Serial LCD Backpack
Yep,
That one has caught me several times!
I'm not sure if Microchip makes any PICS where the MCLR pin can act as an output.
