serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

My code honours the timing as specified by the lcd defines , timing that most lcd displays need esp the cheapest and oldest examples of them.
If you send data at a rate that exceeds the specified time constraints as defined it will of course fall. The solution is to either pace data transmission or set the defines to the actual speed the lcd can tolerate . The intent of my code is to match data rate to the real speed that the lcd can manage

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

set pace to 1 , and it's working
sEROUT2 lcd,baudR,pace,[254,128,"ABCDEFGHIJKLMNOP"]

thanks.

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

I only tested at 19200 and the Backlight works OK.

But text, could not send up to this moment.

WIll try different Baud Rate. Though I test on a PIC16F1827 at 32MHz.

Ioannis

2 Attachment(s)

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

when testing baud rate, usualy I start at 300 and up

when it stopped working then I set pace = 1

and re-start from the last baud rate tested.

16F690 Xtal 20Mhz

set pace to 1
sEROUT2 lcd,baudR,pace,[254,128,"ABCDEFGHIJKLMNOP"]

from my code here's the tested baud rate .
and when booting the PIC's at different baud rate the sender 12F683 and receiver 16F690 the LCD screen light up right away and start displaying text, and back light on/off
there's no lag for the first receiving if I remember correctly the pace for the sender is set = 0.

Attachment 9994

Also I add baud rate selection jumpers on the Backpack''

Attachment 9995

' Jumpers
'
J3 300 600 1200 2400 4800 9600 14400 19200 28800 38400
' 1--2 RB7 On On On On On On
' 3--4 RA2 On On On On
' 5--6 RA1 On On On On
' 7--8 RA3 On On On

' Baud Rate SW Selection (PCB J3)
If PORTA = 001110 And PORTB.7 = 1 Then BaudR = 3313 ' 300
If PORTA = 001110 And PORTB.7 = 0 Then BaudR = 1646 ' 600
If PORTA = 001010 And PORTB.7 = 1 Then BaudR = 813 ' 1200
If PORTA = 001100 And PORTB.7 = 1 Then BaudR = 396 ' 2400
If PORTA = 000110 And PORTB.7 = 1 Then BaudR = 188 ' 4800
If PORTA = 001010 And PORTB.7 = 0 Then BaudR = 84 ' 9600
If PORTA = 001100 And PORTB.7 = 0 Then BaudR = 49 ' 14400
If PORTA = 000110 And PORTB.7 = 0 Then BaudR = 32 ' 19200
If PORTA = 001000 And PORTB.7 = 0 Then BaudR = 15 ' 28800
If PORTA = 000000 And PORTB.7 = 0 Then BaudR = 6 ' 38400

1 Attachment(s)

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

from my last edit,

' Jumpers
' J3 300 600 1200 2400 4800 9600 14400 19200 28800 38400
' 1--2 RB7 On On On On On On
' 3--4 RA2 On On On On
' 5--6 RA1 On On On On
' 7--8 RA3 On On On

I think courier new does not take spaces !
better use screen cap

Attachment 9996

1 Attachment(s)

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

edited BaudR var word : baudr = 3313 and TRISA = 111110

1st receiving random characters
2nd normal

what could be done to avoid the first
thanks.

Attachment 9997

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

its always better to use the hardware than bit-banged routines and there is nothing better than a ring-buffer to overcome traffic snarls

Code:

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Name : 16F690 LCD BACKPACK ' Date : oct 2025 richard ' Note : RING BUFFERED ' Notes : 19200 Intrc_OSC 8Mhz ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' #CONFIG cfg = _INTRC_OSC_NOCLKOUT cfg&= _WDT_OFF cfg&= _PWRTE_OFF cfg&= _MCLRE_OFF cfg&= _CP_OFF cfg&= _CPD_OFF cfg&= _BOD_OFF cfg&= _IESO_OFF cfg&= _FCMEN_OFF __CONFIG cfg #ENDCONFIG DEFINE OSC 8 DEFINE INTHAND myint ANSEL = 0 ' Set all pins digital ANSELH = 0 ' Set all pins digital OPTION_REG.7 = 0 ' PORTA/PORTB pull-ups are enabled by individual port latch values CLEAR DEFINE LCD_BITS 8 'defines the number of data interface lines (4 or 8) DEFINE LCD_DREG PORTC 'defines the port where data lines are connected to DEFINE LCD_RSREG PORTB 'defines the port where RS line is connected to DEFINE LCD_RSBIT 6 'defines the pin where RS line is connected to DEFINE LCD_EREG PORTB 'defines the port where E line is connected to DEFINE LCD_EBIT 4 'defines the pin where E line is connected DEFINE LCD_COMMANDUS 1500 'defines the delay after LCDOUT statement DEFINE LCD_DATAUS 50 'delay in micro seconds RCSTA = $90 ' Enable serial port & continuous receive TXSTA = $20 ' Enable transmit, BRGH = 0 SPBRG = 25 ' 19200 Baud @ 8MHz, 0.16% SPBRGH = 0 BAUDCTL.3 = 1 ' Enable 16 bit baudrate generator wsave VAR BYTE $70 SYSTEM ;wsave in access RAM ssave VAR BYTE BANK0 SYSTEM psave VAR BYTE BANK0 SYSTEM index_in VAR BYTE bank0 ' Pointer - next empty location in buffer index_out VAR BYTE bank0 ' Pointer - location of oldest character in buffer errflag VAR BYTE bank0 ' Error flag UartFlag VAR errflag.0 BufferFlag VAR errflag.1 buffer_size CON 32 ' Sets the size of the ring buffer buffer VAR BYTE[buffer_size] ' Array variable for holding received characters bufchar VAR BYTE ' Stores the character retrieved from the buffer Bl var byte GOTO overint ' Jump over the interrupt handler ASM myint if CODE_SIZE <= 2 ; If less than 2K code space ; Save the state of critical registers (PIC12/PIC16) movwf wsave ; Save W swapf STATUS,W ; Swap STATUS to W (swap avoids changing STATUS) clrf STATUS ; Clear STATUS movwf ssave ; Save swapped STATUS movf PCLATH,W ; Move PCLATH to W movwf psave ; Save PCLATH endif ; Check for hardware overrun error btfsc RCSTA,OERR ; Check for usart overrun goto usart_err ; jump to assembly error routine ; Test for buffer overrun incf _index_in,W ; Increment index_in to W subwf _index_out,W ; Subtract indexes to test for buffer overrun btfsc STATUS,Z ; check for zero (index_in = index_out) goto buffer_err ; jump to error routine if zero ; Increment the index_in pointer and reset it if it's outside the ring buffer incf _index_in,F ; Increment index_in to index_in movf _index_in,W ; Move new index_in to W sublw _buffer_size-1; Subtract index_in from buffer_size-1 btfss STATUS, C ; If index_in => buffer_size clrf _index_in ; Clear index_in ; Set FSR with the location of the next empty location in buffer movlw _buffer ;Store the High byte of buffer to FSR movwf FSR addwf _index_in,W ; Add index_in to point to next empty slot movwf FSR ; Store Low byte of pointer in FSR ; Read and store the character from the USART movf RCREG,W ; Read the received character movwf INDF ; Put the received character in FSR location BTFSC PIR1,RCIF ;ANY MORE ? goto myint finished ; Restore the state of critical registers (PIC12/PIC16) movf psave,W ; restore PCLATH movwf PCLATH swapf ssave,W ; restore STATUS movwf STATUS swapf wsave,F ; restore W (swap avoids changing STATUS) swapf wsave,W retfie ; Return from interrupt ; Error routines buffer_err ; Jump here on buffer error bsf _errflag,1 ; Set the buffer flag usart_err ; Jump here on USART error bsf _errflag,0 ; Set the USART flag movf RCREG, W ; Trash the received character goto finished ; Restore state and return to program ENDASM overint: TRISC = 0 TRISB = % 10101111 TRISA = % 11111110 OSCCON = $70 PAUSE 500 hserout ["ready @19200"] LCDOUT $FE,1 LCDOUT "ready @19200" PAUSE 500 @ bsf LCD_RSREG ,LCD_RSBIT INTCON = $C0 PIE1.5 = 1 GOSUB ERROR main: IF errflag Then GOSUB error ' Goto error routine if needed IF index_in = index_out Then main ' loop if nothing in buffer GoSub getbuf ' Get a character from buffer ' hserout [bufchar] ' Send the character to terminal if bl then if bufchar = 0 then porta.0 = 0 ' Back Light OFF endif if bufchar = 8 then porta.0 = 1 ' Back Light ON endif bl = 0 goto main endif if bufchar = 255 then bl = 1 goto main endif if bufchar = 254 then @ bcf LCD_RSREG ,LCD_RSBIT goto main endif @ MOVE?BB _bufchar,R3 @ L?CALL lcdsend @ bsf LCD_RSREG ,LCD_RSBIT goto main ' loop back to top error: ' Display error message INTCON = 0 ' Disable interrupts while in the error routine IF errflag.1 Then ' Determine the error hserout ["B!",13]' Display buffer error on line-2 Else hserout ["U!",13] ' Display usart error on line_2 EndIF PIR1.5=0 errflag = 0 ' Reset the error flag ;clear any rcsta error RCSTA.4=0 'CREN = 0 Disable continuous receive to clear hardware error RCSTA.4=1 'CREN = 1 Enable continuous receive INTCON = %11000000 ' Enable interrupts RETURN ' repeat getbuf: ' Move the next character in buffer to bufchar index_out = index_out + 1 ' Increment index_out pointer (0 to 31) IF index_out => buffer_size Then index_out = 0 ' Reset pointer if outside buffer bufchar = buffer[index_out] ' Read buffer location(index_out) Return

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

ASM , very impressif code,

thanks.

1 Attachment(s)

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

here's the revised baud rate test chart

Attachment 9998

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

Tried different baud rate but still only Backlight work. The rest is just irrelevant characters on screen.

Then tried the new code of Richards, but have 1827 chip, so asm code is not compatible.

Gave up...

Ioannis

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

maybe the chip?

for my part I used

12F683, 16F690 old regular Pic.

I tried richard code, and it's impressive asm code, that I can't do for sure.

so I stick to basic.

when you're back on this LCD, try this 'self text' backpack for 16F690 maybe it will give a hint.

Code:

''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Name : 16F690 LCD BACKPACK Self Text ' File : "D:\PIC\PBP3\16F690\LCD BACKPACK\16F690 LCD BACKPACK Self Text.pbp" ' Date : Oct 4-2025 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Serin2 '#CONFIG ' __config _INTRC_OSC_CLKOUT & _WDT_OFF & _PWRTE_OFF & _MCLRE_OFF & _CP_OFF & _CPD_OFF & _BOD_OFF & _IESO_OFF & _FCMEN_OFF '#ENDCONFIG ' HSERIN #CONFIG __config _HS_OSC & _WDT_OFF & _PWRTE_OFF & _MCLRE_OFF & _CP_OFF & _CPD_OFF & _BOD_OFF & _IESO_OFF & _FCMEN_OFF #ENDCONFIG DEFINE OSC 20 ' Core is running at EXT-CRYSTAL 20MHz PBP 33,217 'DEFINE OSC 8 ANSEL = 0 ' Set all pins digital ANSELH = 0 ' Set all pins digital OPTION_REG.7 = 0 ' PORTA/PORTB pull-ups are enabled by individual port latch values CM1CON0 = 0 ' Analog comparators off En var Portb.4 : low en RS var Portb.6 : low rs B1 var byte : b1 = 0 C VAR BYTE : C = 100 I VAR BYTE ' 1602 ArrayA var Byte [16] : ARRAYWRITE ArrayA,["ABCDEF1234567890"] ' Line 1 ArrayB var Byte [16] : ARRAYWRITE ArrayB,["1234567890!@#$%^"] ' Line 2 ' 2004 'ArrayC var Byte [20] : ARRAYWRITE ArrayC,["ABCDEF1234567890!@#$"] ' Line 1 'ArrayD var Byte [20] : ARRAYWRITE ArrayD,["1234567890!@#$%^!@#$"] ' Line 2 'ArrayE var Byte [20] : ARRAYWRITE ArrayE,["ABCDEF1234567890!@#$"] ' Line 3 'ArrayF var Byte [20] : ARRAYWRITE ArrayF,["1234567890!@#$%^!@#$"] ' Line 4 TRISA = 0 : TRISB = %00100000 : TRISC = 0 PORTA = 0 : PORTB = 0 : PORTC = 0 OSCCON = $70 pause 100 high Porta.0 ' Backlight ON gosub LCDinit ' initialise LCD pause 100 main: ' 1602 Low RS : PORTC = 128 : High En : PauseUS 1 : Low En : High RS : Pause 3 ' Line 1 For I = 0 To 15 PORTC = ArrayA[I] High En : PauseUS 1 : Low En Pause C Next I Low RS : PORTC = 192 : High En : PauseUS 1 : Low En : High RS : Pause 3 ' Line 2 For I = 0 To 15 PORTC = ArrayB[I] High En : PauseUS 1 : Low En Pause C Next I ' 2004 'Low RS : PORTC = 128 : High En : PauseUS 1 : Low En : High RS : Pause 3 ' Line 1 'For I = 0 To 19 ' PORTC = ArrayC[I] ' High En : PauseUS 1 : Low En ' Pause C 'Next I 'Low RS : PORTC = 192 : High En : PauseUS 1 : Low En : High RS : Pause 3 ' Line 2 'For I = 0 To 19 ' PORTC = ArrayD[I] ' High En : PauseUS 1 : Low En ' Pause C 'Next I 'Low RS : PORTC = 148 : High En : PauseUS 1 : Low En : High RS : Pause 3 ' Line 3 'For I = 0 To 19 ' PORTC = ArrayE[I] ' High En : PauseUS 1 : Low En ' Pause C 'Next I 'Low RS : PORTC = 212 : High En : PauseUS 1 : Low En : High RS : Pause 3 ' Line 4 'For I = 0 To 19 ' PORTC = ArrayF[I] ' High En : PauseUS 1 : Low En ' Pause C 'Next I Pause 1000 Low RS : PORTC = 1 : High En : PauseUS 1 : Low En : High RS : PauseUS 4 ' Clear display Pause 500 'Low PORTA.0 ' Bacck Light off Pause 200 High PORTA.0 ' Bacck Light on Pause 200 C = C - 20 If C < 20 Then C = 100 EndIf GoTo main LCDINIT: ' Standard LCD Module Initialisation PORTC = %00000001 : HIGH EN : PAUSEus 1 : LOW EN : pause 4 ' Clear Display PORTC = %00000010 : HIGH EN : PAUSEus 1 : LOW EN : pause 2 ' Return Home PORTC = %00111000 : HIGH EN : PAUSEus 1 : LOW EN : Pause 2 ' 8 bit, 2 line, 5x8 Characters PORTC = %00000110 : HIGH EN : PAUSEus 1 : LOW EN : Pause 2 ' Entry mode PORTC = %00001100 : HIGH EN : PAUSEus 1 : LOW EN : Pause 2 ' %00001DCB Display on/off, Cursor on/off, Blink y/n RETURN

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

For a 1827 it would look like this [untested]

Code:

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Name : 16F1827 LCD BACKPACK * ' Date : oct 2025 richard * ' Note : RING BUFFERED * ' Notes : DEFA BAUD RATE 9600 Intrc_OSC 8Mhz * ' eeprom full case is unhandled,factory reset would be advisable * ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' #CONFIG __config _CONFIG1, _FOSC_INTOSC & _WDTE_ON & _PWRTE_OFF & _MCLRE_ON & _CP_OFF & _CPD_OFF & _BOREN_ON & _CLKOUTEN_OFF & _IESO_ON & _FCMEN_ON __config _CONFIG2, _WRT_OFF & _PLLEN_OFF & _STVREN_ON & _BORV_19 & _LVP_OFF #ENDCONFIG ;commands eg SEROUT2 lcd,84,[255,11] set baudrate from 9600 to 19200 '255 0/8 backlight '255 10/11/12 baud rate 9600/19200/38400 '255 "F" factory reset DEFINE OSC 8 DEFINE INTHAND myint DEFINE WRITE_INT 1 ANSELA = 0 ' Set all pins digital ANSELB = 0 ' Set all pins digital OPTION_REG.7 = 0 ' PORTA/PORTB pull-ups are enabled by individual port latch values CLEAR DEFINE LCD_BITS 4 'defines the number of data interface lines (4 or 8) DEFINE LCD_DREG PORTA 'defines the port where data lines are connected to DEFINE LCD_DBIT 4 DEFINE LCD_RSREG PORTB 'defines the port where RS line is connected to DEFINE LCD_RSBIT 6 'defines the pin where RS line is connected to DEFINE LCD_EREG PORTB 'defines the port where E line is connected to DEFINE LCD_EBIT 4 'defines the pin where E line is connected DEFINE LCD_COMMANDUS 1500 'defines the delay after LCDOUT statement DEFINE LCD_DATAUS 50 'delay in micro seconds RCSTA = $90 ' Enable serial port & continuous receive TXSTA = $20 ' Enable transmit, BRGH = 0 SP1BRG = 51 ' 19200 Baud @ 8MHz, 0.16%, 51 ' 9600 Baud @ 8MHz, 0.16%, 12 ' 38400 Baud @ 8MHz, 0.16% SP1BRGH = 0 BAUDCON.3 = 1 ' Enable 16 bit baudrate generator buffer_size CON 32 ' Sets the size of the ring buffer index_in VAR BYTE bank0 ' Pointer - next empty location in buffer index_out VAR BYTE bank0 ' Pointer - location of oldest character in buffer errflag VAR BYTE bank0 ' Error flag UartFlag VAR errflag.0 BufferFlag VAR errflag.1 buffer VAR BYTE[buffer_size] ' Array variable for holding received characters bufchar VAR BYTE ' Stores the character retrieved from the buffer Bl var byte inx var byte Br var byte GOTO overint ' Jump over the interrupt handler ASM myint ; Check for hardware overrun error btfsc RCSTA,OERR ; Check for usart overrun goto usart_err ; jump to assembly error routine ; Test for buffer overrun incf _index_in,W ; Increment index_in to W subwf _index_out,W ; Subtract indexes to test for buffer overrun btfsc STATUS,Z ; check for zero (index_in = index_out) goto buffer_err ; jump to error routine if zero ; Increment the index_in pointer and reset it if it's outside the ring buffer incf _index_in,F ; Increment index_in to index_in movf _index_in,W ; Move new index_in to W sublw _buffer_size-1; Subtract index_in from buffer_size-1 btfss STATUS, C ; If index_in => buffer_size clrf _index_in ; Clear index_in ; Set FSR with the location of the next empty location in buffer movlw _buffer ;Store the High byte of buffer to FSR movwf FSR0 addwf _index_in,W ; Add index_in to point to next empty slot movwf FSR0 ; Store Low byte of pointer in FSR ; Read and store the character from the USART movf RCREG,W ; Read the received character movwf INDF0 ; Put the received character in FSR location BTFSC PIR1,RCIF ;ANY MORE ? goto myint finished retfie ; Return from interrupt ; Error routines buffer_err ; Jump here on buffer error bsf _errflag,1 ; Set the buffer flag usart_err ; Jump here on USART error bsf _errflag,0 ; Set the USART flag movf RCREG, W ; Trash the received character goto finished ; Restore state and return to program ENDASM overint: TRISB = % 00101111 TRISA = % 11110000 OSCCON = $70 PAUSE 500 gosub getbaud PAUSE 5 LCDOUT $FE,1 hserout [13,"ready"] LCDOUT "ready " if br==51 then hserout ["@9600"] LCDOUT "@9600" elseif br==25 then hserout ["@19200"] LCDOUT "@19200" else hserout ["@38400"] LCDOUT "@38400" endif PAUSE 500 @ bsf LCD_RSREG ,LCD_RSBIT GOSUB error INTCON = $C0 PIE1.5 = 1 main: IF errflag Then GOSUB error ' Goto error routine if needed IF index_in = index_out Then main ' loop if nothing in buffer GoSub getbuf ' Get a character from buffer if bl then if bufchar = 0 then porta.0 = 0 ' Back Light OFF endif if bufchar = 8 then porta.0 = 1 ' Back Light ON endif if bufchar = 10 then write inx+1,51 gosub getbaud endif if bufchar = 11 then write inx+1,25 gosub getbaud endif if bufchar = 12 then write inx+1,12 gosub getbaud endif if bufchar = "F" then gosub factory endif bl = 0 goto main endif if bufchar = 255 then bl = 1 goto main endif if bufchar = 254 then @ bcf LCD_RSREG ,LCD_RSBIT goto main endif @ MOVE?BB _bufchar,R3 @ L?CALL lcdsend @ bsf LCD_RSREG ,LCD_RSBIT goto main ' loop back to top error: ' Display error message INTCON = 0 ' Disable interrupts while in the error routine IF errflag.1 Then ' Determine the error hserout ["B!",13]' Display buffer error on line-2 Else hserout ["U!",13] ' Display usart error on line_2 EndIF errflag = 0 ' Reset the error flag ;clear any rcsta error RCSTA.4 = 0 'CREN = 0 Disable continuous receive to clear hardware error RCSTA.4 = 1 'CREN = 1 Enable continuous receive INTCON = %11000000 ' Enable interrupts RETURN ' repeat getbuf: ' Move the next character in buffer to bufchar index_out = index_out + 1 ' Increment index_out pointer (0 to 31) IF index_out => buffer_size Then index_out = 0 ' Reset pointer if outside buffer bufchar = buffer[index_out] ' Read buffer location(index_out) Return getbaud: bufchar = 0 inx = 255 read inx,Br while Br==255 read inx,Br if Br==255 then if inx == 0 then br=51 write inx,51 hserout [13,"init@9600 " ,dec inx,",",dec Br] else inx = inx-1 endif endif wend ;note if inx=255 then eeprom full hserout [" index " ,dec inx,",",dec Br] SP1BRG = Br Return factory: write 0,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 16,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 32,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 48,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 64,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 80,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 96,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 112,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 128,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 144,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 160,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 176,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 192,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 208,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 224,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 240,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff gosub getbaud Return

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

a bit out of practice , forgot porta.4 is input only plus 1827 has bits and pieces in other banks

so tested and working version

Code:

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Name : 16F1827 LCD BACKPACK * ' Date : oct 2025 richard * ' Note : RING BUFFERED * ' Notes : DEFA BAUD RATE 9600 Intrc_OSC 8Mhz * ' eeprom full case is unhandled,factory reset would be advisable * ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' #CONFIG __config _CONFIG1, _FOSC_INTOSC & _WDTE_ON & _PWRTE_OFF & _MCLRE_ON & _CP_OFF & _CPD_OFF & _BOREN_ON & _CLKOUTEN_OFF & _IESO_ON & _FCMEN_ON __config _CONFIG2, _WRT_OFF & _PLLEN_OFF & _STVREN_ON & _BORV_19 & _LVP_OFF #ENDCONFIG ;commands eg SEROUT2 lcd,84,[255,11] set baudrate from 9600 to 19200 '255 0/8 backlight '255 10/11/12 baud rate 9600/19200/38400 '255 "F" factory reset ;TX PORTB.2 RX PORTB.1 BACKLIGHT PORTB.0 DEFINE OSC 8 DEFINE INTHAND myint DEFINE WRITE_INT 1 ANSELA = 0 ' Set all pins digital ANSELB = 0 ' Set all pins digital ' OPTION_REG.7 = 0 ' PORTA/PORTB pull-ups are enabled by individual port latch values CLEAR DEFINE LCD_BITS 4 'defines the number of data interface lines (4 or 8) DEFINE LCD_DREG PORTA 'defines the port where data lines are connected to DEFINE LCD_DBIT 0 DEFINE LCD_RSREG PORTB 'defines the port where RS line is connected to DEFINE LCD_RSBIT 6 'defines the pin where RS line is connected to DEFINE LCD_EREG PORTB 'defines the port where E line is connected to DEFINE LCD_EBIT 4 'defines the pin where E line is connected DEFINE LCD_COMMANDUS 1500 'defines the delay after LCDOUT statement DEFINE LCD_DATAUS 50 'delay in micro seconds RCSTA = $90 ' Enable serial port & continuous receive TXSTA = $20 ' Enable transmit, BRGH = 0 SP1BRG = 51 ' 19200 Baud @ 8MHz, 0.16%, 51 ' 9600 Baud @ 8MHz, 0.16%, 12 ' 38400 Baud @ 8MHz, 0.16% SP1BRGH = 0 BAUDCON.3 = 1 ' Enable 16 bit baudrate generator buffer_size CON 32 ' Sets the size of the ring buffer index_in VAR BYTE bank0 ' Pointer - next empty location in buffer index_out VAR BYTE bank0 ' Pointer - location of oldest character in buffer errflag VAR BYTE bank0 ' Error flag UartFlag VAR errflag.0 BufferFlag VAR errflag.1 buffer VAR BYTE[buffer_size] ' Array variable for holding received characters bufchar VAR BYTE ' Stores the character retrieved from the buffer Bl var byte inx var byte Br var byte GOTO overint ' Jump over the interrupt handler ASM myint ; Check for hardware overrun error banksel RCSTA btfsc RCSTA,OERR ; Check for usart overrun goto usart_err ; jump to assembly error routine ; Test for buffer overrun banksel 0 incf _index_in,W ; Increment index_in to W subwf _index_out,W ; Subtract indexes to test for buffer overrun btfsc STATUS,Z ; check for zero (index_in = index_out) goto buffer_err ; jump to error routine if zero ; Increment the index_in pointer and reset it if it's outside the ring buffer incf _index_in,F ; Increment index_in to index_in movf _index_in,W ; Move new index_in to W sublw _buffer_size-1; Subtract index_in from buffer_size-1 btfss STATUS, C ; If index_in => buffer_size clrf _index_in ; Clear index_in ; Set FSR with the location of the next empty location in buffer movlw High _buffer ;Store the High byte of buffer to FSR0H movwf FSR0H movlw Low _buffer ; Get the Low byte of buffer[0] addwf _index_in,W ; Add index_in to point to next empty slot movwf FSR0L ; Store Low byte of pointer in FSR0 ; Read and store the character from the USART banksel RCREG movf RCREG,W ; Read the received character movwf INDF0 ; Put the received character in FSR location banksel PIR1 BTFSC PIR1,RCIF ;ANY MORE ? goto myint finished RST?RP retfie ; Return from interrupt ; Error routines buffer_err ; Jump here on buffer error bsf _errflag,1 ; Set the buffer flag usart_err ; Jump here on USART error banksel _errflag bsf _errflag,0 ; Set the USART flag banksel RCREG movf RCREG, W ; Trash the received character goto finished ; Restore state and return to program ENDASM overint: TRISB = %10101010 TRISA = %11110000 OSCCON = $70 PAUSE 500 gosub getbaud PAUSE 5 LCDOUT $FE,1 hserout [13,"ready"] LCDOUT "ready " if br==51 then hserout ["@9600"] LCDOUT "@9600" elseif br==25 then hserout ["@19200"] LCDOUT "@19200" else hserout ["@38400"] LCDOUT "@38400" endif PAUSE 500 @ bsf LCD_RSREG ,LCD_RSBIT GOSUB error INTCON = $C0 PIE1.5 = 1 main: IF errflag Then GOSUB error ' Goto error routine if needed IF index_in = index_out Then main ' loop if nothing in buffer GoSub getbuf ' Get a character from buffer if bl then if bufchar = 0 then portB.0 = 0 ' Back Light OFF endif if bufchar = 8 then portB.0 = 1 ' Back Light ON endif if bufchar = 10 then write inx+1,51 gosub getbaud endif if bufchar = 11 then write inx+1,25 gosub getbaud endif if bufchar = 12 then write inx+1,12 gosub getbaud endif if bufchar = "F" then gosub factory endif bl = 0 goto main endif if bufchar = 255 then bl = 1 goto main endif if bufchar = 254 then @ bcf LCD_RSREG ,LCD_RSBIT goto main endif @ MOVE?BB _bufchar,R3 @ MOVE?CT 1,FLAGS ,0 @ L?CALL lcdsend @ bsf LCD_RSREG ,LCD_RSBIT goto main ' loop back to top error: ' Display error message INTCON = 0 ' Disable interrupts while in the error routine IF errflag.1 Then ' Determine the error hserout ["B!",13]' Display buffer error on line-2 Else hserout ["U!",13] ' Display usart error on line_2 EndIF errflag = 0 ' Reset the error flag ;clear any rcsta error RCSTA.4 = 0 'CREN = 0 Disable continuous receive to clear hardware error RCSTA.4 = 1 'CREN = 1 Enable continuous receive INTCON = %11000000 ' Enable interrupts RETURN ' repeat getbuf: ' Move the next character in buffer to bufchar index_out = index_out + 1 ' Increment index_out pointer (0 to 31) IF index_out => buffer_size Then index_out = 0 ' Reset pointer if outside buffer bufchar = buffer[index_out] ' Read buffer location(index_out) Return getbaud: bufchar = 0 inx = 255 read inx,Br while Br==255 read inx,Br if Br==255 then if inx == 0 then br=51 write inx,51 hserout [13,"init@9600 " ,dec inx,",",dec Br] else inx = inx-1 endif endif wend ;note if inx=255 then eeprom full hserout [" index " ,dec inx,",",dec Br] SP1BRG = Br Return factory: write 0,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 16,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 32,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 48,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 64,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 80,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 96,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 112,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 128,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 144,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 160,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 176,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 192,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 208,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 224,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 240,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff gosub getbaud Return

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

Thanks Richard.

The new code:

works OK with LCD Backlight On/Off

works OK sending text over the serial port

works OK sending commands to LCD over serial port

On power up LCD shows ready@38400 and this does not change. But the communication baud rate is 9600. With 255,10 or 11 or12 can change baud rate but it is not displayed on LCD. Though higher baud rates need pace.

On power up the terminal shows ready@38400U!

Have done two changes on port b to drive the RS and E signal on PortB.3 and PortB.4.

PortB.1 is the RS-232 driver TX output from PIC
PortB.2 is the RS-232 driver RX input to PIC

Ioannis

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

Excellent news,,

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

removed debug messages that are sent before spbrg set to correct value
since 1827 has more resources have increased buffer size, u may not need pacing any longer to compensate for
the 4 bit lcd interface being a bit slower

baud rate is only shown on lcd at boot , setting is stored in eeprom

Code:

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Name : 16F1827 LCD BACKPACK * ' Date : oct 2025 richard * ' Note : RING BUFFERED * ' Notes : DEFA BAUD RATE 9600 Intrc_OSC 8Mhz * ' eeprom full case is unhandled,factory reset would be advisable * ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' #CONFIG __config _CONFIG1, _FOSC_INTOSC & _WDTE_ON & _PWRTE_OFF & _MCLRE_ON & _CP_OFF & _CPD_OFF & _BOREN_ON & _CLKOUTEN_OFF & _IESO_ON & _FCMEN_ON __config _CONFIG2, _WRT_OFF & _PLLEN_OFF & _STVREN_ON & _BORV_19 & _LVP_OFF #ENDCONFIG ;commands eg SEROUT2 lcd,84,[255,11] set baudrate from 9600 to 19200 '255 0/8 backlight '255 10/11/12 baud rate 9600/19200/38400 '255 "F" factory reset ;TX PORTB.2 RX PORTB.1 BACKLIGHT PORTB.0 DEFINE OSC 8 DEFINE INTHAND myint DEFINE WRITE_INT 1 ANSELA = 0 ' Set all pins digital ANSELB = 0 ' Set all pins digital ' OPTION_REG.7 = 0 ' PORTA/PORTB pull-ups are enabled by individual port latch values CLEAR DEFINE LCD_BITS 4 'defines the number of data interface lines (4 or 8) DEFINE LCD_DREG PORTA 'defines the port where data lines are connected to DEFINE LCD_DBIT 0 DEFINE LCD_RSREG PORTB 'defines the port where RS line is connected to DEFINE LCD_RSBIT 6 'defines the pin where RS line is connected to DEFINE LCD_EREG PORTB 'defines the port where E line is connected to DEFINE LCD_EBIT 4 'defines the pin where E line is connected DEFINE LCD_COMMANDUS 1500 'defines the delay after LCDOUT statement DEFINE LCD_DATAUS 50 'delay in micro seconds RCSTA = $90 ' Enable serial port & continuous receive TXSTA = $20 ' Enable transmit, BRGH = 0 SP1BRG = 51 ' 19200 Baud @ 8MHz, 0.16%, 51 ' 9600 Baud @ 8MHz, 0.16%, 12 ' 38400 Baud @ 8MHz, 0.16% SP1BRGH = 0 BAUDCON.3 = 1 ' Enable 16 bit baudrate generator buffer_size CON 64 ' Sets the size of the ring buffer index_in VAR BYTE bank0 ' Pointer - next empty location in buffer index_out VAR BYTE bank0 ' Pointer - location of oldest character in buffer errflag VAR BYTE bank0 ' Error flag UartFlag VAR errflag.0 BufferFlag VAR errflag.1 buffer VAR BYTE[buffer_size] ' Array variable for holding received characters bufchar VAR BYTE ' Stores the character retrieved from the buffer Bl var byte inx var byte Br var byte GOTO overint ' Jump over the interrupt handler ASM myint ; Check for hardware overrun error banksel RCSTA btfsc RCSTA,OERR ; Check for usart overrun goto usart_err ; jump to assembly error routine ; Test for buffer overrun banksel 0 incf _index_in,W ; Increment index_in to W subwf _index_out,W ; Subtract indexes to test for buffer overrun btfsc STATUS,Z ; check for zero (index_in = index_out) goto buffer_err ; jump to error routine if zero ; Increment the index_in pointer and reset it if it's outside the ring buffer incf _index_in,F ; Increment index_in to index_in movf _index_in,W ; Move new index_in to W sublw _buffer_size-1; Subtract index_in from buffer_size-1 btfss STATUS, C ; If index_in => buffer_size clrf _index_in ; Clear index_in ; Set FSR with the location of the next empty location in buffer movlw High _buffer ;Store the High byte of buffer to FSR0H movwf FSR0H movlw Low _buffer ; Get the Low byte of buffer[0] addwf _index_in,W ; Add index_in to point to next empty slot movwf FSR0L ; Store Low byte of pointer in FSR0 ; Read and store the character from the USART banksel RCREG movf RCREG,W ; Read the received character movwf INDF0 ; Put the received character in FSR location banksel PIR1 BTFSC PIR1,RCIF ;ANY MORE ? goto myint finished ;RST?RP retfie ; Return from interrupt ; Error routines buffer_err ; Jump here on buffer error bsf _errflag,1 ; Set the buffer flag usart_err ; Jump here on USART error banksel _errflag bsf _errflag,0 ; Set the USART flag banksel RCREG movf RCREG, W ; Trash the received character goto finished ; Restore state and return to program ENDASM overint: TRISB = % 00101010 TRISA = % 11110000 OSCCON = $70 PAUSE 500 gosub getbaud PAUSE 5 LCDOUT $FE,1 hserout [13,"ready"] LCDOUT "ready " if br==51 then hserout ["@9600"] LCDOUT "@9600" elseif br==25 then hserout ["@19200"] LCDOUT "@19200" else hserout ["@38400"] LCDOUT "@38400" endif PAUSE 500 @ bsf LCD_RSREG ,LCD_RSBIT GOSUB error INTCON = $C0 PIE1.5 = 1 main: IF errflag Then GOSUB error ' Goto error routine if needed IF index_in = index_out Then main ' loop if nothing in buffer GoSub getbuf ' Get a character from buffer if bl then if bufchar = 0 then portB.0 = 0 ' Back Light OFF portB.7 = 1 ' Back Light OFF endif if bufchar = 8 then portB.0 = 1 ' Back Light ON portB.7 = 0 ' Back Light OFF endif if bufchar = 10 then write inx+1,51 gosub getbaud endif if bufchar = 11 then write inx+1,25 gosub getbaud endif if bufchar = 12 then write inx+1,12 gosub getbaud endif if bufchar = "F" then gosub factory endif bl = 0 goto main endif if bufchar = 255 then bl = 1 goto main endif if bufchar = 254 then @ bcf LCD_RSREG ,LCD_RSBIT goto main endif @ MOVE?BB _bufchar,R3 @ MOVE?CT 1,FLAGS ,0 @ L?CALL lcdsend @ bsf LCD_RSREG ,LCD_RSBIT goto main ' loop back to top error: ' Display error message INTCON = 0 ' Disable interrupts while in the error routine IF errflag.1 Then ' Determine the error hserout [" Buffer overflow",13]' Display buffer error on line-2 Else hserout [" Uart reset",13] ' Display usart error on line_2 EndIF errflag = 0 ' Reset the error flag ;clear any rcsta error RCSTA.4 = 0 'CREN = 0 Disable continuous receive to clear hardware error RCSTA.4 = 1 'CREN = 1 Enable continuous receive INTCON = % 11000000 ' Enable interrupts RETURN ' repeat getbuf: ' Move the next character in buffer to bufchar index_out = index_out + 1 ' Increment index_out pointer (0 to 31) IF index_out => buffer_size Then index_out = 0 ' Reset pointer if outside buffer bufchar = buffer[index_out] ' Read buffer location(index_out) Return getbaud: bufchar = 0 inx = 255 read inx,Br while Br==255 read inx,Br if Br==255 then if inx == 0 then br=51 write inx,51 ' hserout [13,"init@9600 " ,dec inx,",",dec Br] else inx = inx-1 endif endif wend ;note if inx=255 then eeprom full ' hserout [" index " ,dec inx,",",dec Br] SP1BRG = Br Return factory: write 0,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 16,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 32,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 48,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 64,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 80,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 96,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 112,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 128,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 144,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 160,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 176,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 192,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 208,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 224,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff write 240,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff,$ff gosub getbaud Return

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

Great work Richard!

Works very well. Thank you.

I had to change LCD_COMMANDUS to 2000 from 1500 for best performance.

I just did not understood what all these ff's at the end of the code do.

Ioannis

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

Quote:

I had to change LCD_COMMANDUS to 2000 from 1500 for best performance

not to be unexpected, the LCD timing defines need to match the display in use. some are very slow

Code:

I just did not understood what all these ff's at the end of the code do.

not pretty I agree but its one simple way to erase the eeprom at run time, hence "factory" as in factory reset

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

one last update:

added an PGM Sw on RA3

to edit the baud rate:

turn off the LCD display, press & hold the PGM sw, turn on the LCD
line 1 will show "Press to Select" , line 2 : "Baud Rate:"
release the sw and press it again to select next value (at this point the new value is save to EEPROM memory)
when the desire value is reach, turn off the LCD and turn it on again at this point the LCD will display the baud rate on line 2
and the display is ready to receive a clear LCD command, and data from the sender.

As for different LCD module eg: 1601,1602,2004 1 line, 2 lines 4 lines etc.. the LCD commands is use to control position of the data on the screen.

as of today the 1601, 1602, 2004 have been tested successfuly.

Code:

#CONFIG __config _HS_OSC & _WDT_OFF & _PWRTE_OFF & _MCLRE_OFF & _CP_OFF & _CPD_OFF & _BOD_OFF & _IESO_OFF & _FCMEN_OFF #ENDCONFIG DEFINE OSC 20 ' Running @ 20MHz PBP 33,217 ANSEL = 0 : ANSELH = 0 ' Set all pins digital TRISA = 001000 : TRISB = 100000 : TRISC = 0 ' 0 = OUT, 1 = IN PORTA = 000001 : PORTB = 0 : PORTC = 0 ' 0 = Low 1 = High OSCCON = $78 ' $78=External Xtal $70 = Internal BaudR var word ' Baud Rate word var En var Portb.4 ' LCD Enable RS var Portb.6 ' LCD Register Set B1 var byte ' Serial IN Byte Flag var bit ' Display Baud Rate on Power-up I VAR BYTE : II VAR BYTE : III VAR BYTE ' use in Set1 read 0, word baudr,ii : pause 2 ' Read Baud Rate from EEPROM if ii < 0 or ii > 7 then baudr = 84 : ii = 3 WRITE 0, Word baudr,ii : pause 2 ' Write to EEPROM endif ArrayA var Byte [65] ' Array index (III) 0 5 10 15 20 25 30 35 40~55 56~65 ARRAYWRITE ArrayA,[" 1200 2400 4800 960014400192002880038400Press to Select:Baud Rate:"] gosub LCDinit ' Initialise LCD IF PORTA.3 = 1 THEN ' PGM Switch GOTO Set1 else flag = 1 gosub set2 pause 500 ENDIF main: serin2 Portb.5,baudr,3,main,[b1] ' Serial IN if b1 < 253 then ' if Characters PORTC = b1 HIGH EN : PAUSEus 1 : LOW EN goto main elseif b1 = 254 then ' if LCD Command low RS serin2 Portb.5,baudr,3,main,[b1] PORTC = b1 ' output the data HIGH EN : PAUSEus 1 : LOW EN high RS ' character mode goto main elseif b1 = 255 then ' if Port Command serin2 Portb.5,baudr,3,main,[b1] if b1 = 0 then TOGGLE PORTA.0 ' Toggle Back Light OFF / ON if b1 = 1 then TOGGLE PORTB.7 ' Toggle PORTB.7 ON / OFF if b1 = 2 then TOGGLE PORTA.2 ' Toggle PORTA.2 ON / OFF goto main ' loop back to top ENDIF LCDINIT: ' Standard LCD Module Initialisation PORTC = 000001 : HIGH EN : PAUSEus 1 : LOW EN : pause 4 ' Clear Display PORTC = 000010 : HIGH EN : PAUSEus 1 : LOW EN : pause 2 ' Return Home PORTC = 111000 : HIGH EN : PAUSEus 1 : LOW EN : Pause 2 ' 8 bit, 2 line, 5x8 Characters PORTC = 000110 : HIGH EN : PAUSEus 1 : LOW EN : Pause 2 ' Entry mode PORTC = 001110 : HIGH EN : PAUSEus 1 : LOW EN : Pause 2 ' 001DCB Display on/off, Cursor on/off, Blink y/n RETURN Set1: ' Baud Rate Selection and EEPROM Save at Power ON with Switch press PAUSE 10 ' "Press to Select:" Low RS : PORTC = 128 : High En : PauseUS 1 : Low En : High RS : Pause 3 ' Line 1 For I = 40 To 55 PORTC = ArrayA[I] High En : PauseUS 1 : Low En PAUSE 2 Next I Set2: PAUSE 10 ' "Baud Rate:" Low RS : PORTC = 192 : High En : PauseUS 1 : Low En : High RS : Pause 3 ' Line 2 For I = 56 To 65 PORTC = ArrayA[I] High En : PauseUS 1 : Low En PAUSE 2 Next I Set3: Low RS : PORTC = 203 : High En : PauseUS 1 : Low En : High RS : Pause 3 ' Line 2 PAUSE 2 ' Index IF II = 0 THEN III = 0 : baudr = 813 ' 1200 IF II = 1 THEN III = 5 : baudr = 396 ' 2400 IF II = 2 THEN III = 10 : baudr = 188 ' 4800 IF II = 3 THEN III = 15 : baudr = 84 ' 9600 IF II = 4 THEN III = 20 : baudr = 49 ' 14400 IF II = 5 THEN III = 25 : baudr = 32 ' 19200 IF II = 6 THEN III = 30 : baudr = 15 ' 28800 IF II = 7 THEN III = 35 : baudr = 6 ' 38400 For I = III To (IIi + 4) PORTC = ArrayA[I] High En : PauseUS 1 : Low En PAUSE 2 Next I if flag = 1 then flag = 0 : return endif WRITE 0, Word baudr,ii : pause 2 ' Write to EEPROM II = II + 1 IF II > 7 THEN II = 0 while PORTA.3 = 1 ' Switch Press wend PAUSE 250 while PORTA.3 = 0 ' Switch Release wend pause 250 GOTO set3

Re: serial LCD 1602 Backpack using PIC16F690 for Hitach HD44780

Newhaven Display (newhavendisplay.com) offers a collection of 10 different character LCDs in 2x16, 2x20 and 4x20 formats that are exclusively serial inputs -- I2C, SPI and Async TTL -- and reasonably priced at $15 to $20 U.S. I have a couple of the 2x20's, and they work nicely in all 3 interface modes. Nevertheless, this is a very interesting project as I (like everyone else) have a drawer full of parallel interface HD44780 type LCDs that will be put to better use with this serial interface. Many thanks, and I'll provide you feedback if I have anything useful to contribute.