Serout2 on LCD Shows Junk Characters

[gadelhas]

Hi RossWaddell,

I used this LCD in the past and i had some problems with interrupts. If you are outputing something to the LCD and if an interrupt occurs, the data gets corrupted. If possible, you must disable the interrupt, then send the data with the serout command, and then enable interrupt, of course, if it is allowed to do in your program. When i don't use interrupts, no problem working with this LCD, with serout, serin, serout2, serin2, hserout and hserin!!

EDIT: grrr... Darrel.... get it first!!!!

[RossWaddell]

Thanks Darrel & Gadelhas. Am I right in thinking RA0 is the USART tx pin on the PIC16F1825?

[gadelhas]

Yes. You can have TX on RA0 or RC4, because in this chips is possible to change between those 2 pins, by controlling the APFCON0 and APFCON1 registers.

[RossWaddell]

If I'm using RA0, do I need to set those registers? Because without them the screen is completely blank:

'****************************************************************
'*  Name    : Test_SPWM.pbp                                     *
'*  Author  : Darrel Taylor                                     *
'*  Date    : 9/30/2006                                         *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*          :                                                   *
'****************************************************************


; LCD serout2 command won't work when using interrupts; need to use
; HSEROUT on chip's USART tx pin instead.



' ***************************************************************
' Pin Connections
' ***************************************************************

' RA0                        -> Serial LCD output
' RA1                        -> Middle arm of trim pot (AN1)
' RC0                        -> LED1
' RC1                        -> LED2
' RC2                        -> LED3

DEFINE OSC          16      ; Set oscillator 16Mhz
;DEFINE OSC           4      ; Set oscillator 4Mhz
DEFINE ADC_BITS      8      ; Set number of bits in result
DEFINE ADC_SAMPLEUS  5      ; Set sampling time in uS
DEFINE ADC_CLOCK     3      ; Set clock source (3=rc)

DEFINE  HSER_TXSTA   20h    ; Set transmit status and control register
DEFINE  HSER_BAUD    2400   ; Set baud rate

' ***************************************************************
' Device Fuses
' ***************************************************************
#CONFIG
   __config _CONFIG1, _FOSC_INTOSC & _WDTE_ON & _PWRTE_ON & _MCLRE_OFF & _CP_OFF & _CPD_OFF
   __config _CONFIG2, _PLLEN_OFF & _STVREN_ON & _BORV_LO & _LVP_OFF
#ENDCONFIG

#DEFINE USE_LCD_FOR_DEBUG   ; comment out for non-debug use

' ***************************************************************
' Initialization
' ***************************************************************

OSCCON   = %01111000        ' 16MHz internal osc
;OSCCON   = %01101000        ' 4MHz internal osc

pause 100

; Use PortA.1 (AN1) for ADCIN (trim pot reading)
ANSELA   = %00000010        ; Analog on PORTA.1 (AN1) only
TRISA    = %00000010        ; Input on PORTA.1 (AN1) only
;ADCON1   = %01110000        ; Left-justified results in 8-bits; Fosc/8 (2uS @ 4Mhz)
ADCON1.7 = 0                ; Left-justified results in 8-bits; Fosc/8 (2uS @ 4Mhz)
ANSELC   = 0                ; Diginal only for all PortC pins
TRISC    = %00000000        ; Make all PORTC pins output

#DEFINE USE_LCD_FOR_DEBUG   ; comment out for non-debug use

#IFDEF USE_LCD_FOR_DEBUG
    LCD_PIN    VAR PORTC.4  ' Alias PORTC.4 as "LCD_PIN"
    LCD_INST   CON 254      ' instruction
    LCD_CLR    CON 1        ' Clear screen
    LCD_L1     CON 128      ' LCD line 1
    LCD_L2     CON 192      ' LCD line 2
    LCD_BAUD   CON 16780    ' Baud rate/mode 2600bps for ILM-216 2x16 character display
;    LCD_BAUD   CON 16468    ' Baud rate/mode 9600bps for ILM-216 2x16 character display
    LCD_PACE   CON 1        ' Optional pace value
#ENDIF

' ***************************************************************
' Includes
' ***************************************************************

INCLUDE "DT_INTS-14.bas"            ; Base Interrupt System
INCLUDE "SPWM_INT.bas"              ; Software PWM module

DEFINE SPWM_FREQ  200               ; SPWM Frequency
DEFINE SPWM_RES   256               ; SPWM Resolution

DutyVars   VAR BYTE[3]              ; DutyCycle Variables
  DutyVar1 VAR DutyVars[0]          ; group them in an array for easy access
  DutyVar2 VAR DutyVars[1]          ; with FOR loops etc.
  DutyVar3 VAR DutyVars[2]

ASM
SPWM_LIST  macro                    ; Define Pin's to use for SPWM
     SPWM_PIN  PORTC, 0, _DutyVar1  ; and the associated DutyCycle variables
     SPWM_PIN  PORTC, 1, _DutyVar2  ; Notice the underscore before variables
     SPWM_PIN  PORTC, 2, _DutyVar3
  endm
  SPWM_INIT  SPWM_LIST              ; Initialize the Pins
ENDASM

ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   TMR1_INT,  SPWMhandler,  ASM,  yes
    endm
    INT_CREATE                      ; Creates the interrupt processor
ENDASM

@ INT_ENABLE  TMR1_INT              ; enable Timer 1 interrupts

adval       VAR  WORD       ; stores ADCIN results  
oldDutyVar1 VAR  WORD 
;_____________________________________________________________________________

DutyVar1 = 0
DutyVar2 = 25
DutyVar3 = 255

#IFDEF USE_LCD_FOR_DEBUG
    HSEROUT [LCD_INST, LCD_CLR]
    pause 5
    HSEROUT ["DutyVar1=", DEC DutyVar1, 13, 10] ' Send text followed by carriage return and linefeed
#ENDIF

Main:
   ADCIN 1, adval
   if adval <> oldDutyVar1 then
      oldDutyVar1 = adval
      DutyVar1 = adval

      #IFDEF USE_LCD_FOR_DEBUG
         HSEROUT [DEC DutyVar1, 13, 10] ' Send text followed by carriage return and linefeed
      #ENDIF
   EndIf
   Pause 100
Goto Main

Edit: Adding

APFCON0.2 = 1               ; Tx on RA0

makes the screen not blank, but it's still gobbledy-gook.

[gadelhas]

try with APFCON0.2 = 1, because the chip is initialized with TX on the RC4 pin, (APFCON0.2 = 0), so you must change it. datasheet page 123.

[Darrel Taylor]

The Scott Edwards display is expecting Inverted serial levels.
The USART puts out True levels by default.

Add this setting ...

BAUDCON.4 = 1  ; Transmit inverted data to the TX/CK pin

[RossWaddell]

The Scott Edwards display is expecting Inverted serial levels.
The USART puts out True levels by default.

Add this setting ...

BAUDCON.4 = 1  ; Transmit inverted data to the TX/CK pin

Thanks Darrel! It works now except the LCD shows a strange character in the 1st position (looks like "F1" with the "1" being a subscript).

#IFDEF USE_LCD_FOR_DEBUG
    HSEROUT [LCD_INST, LCD_CLR]
    pause 5
    HSEROUT ["DutyVar1=", DEC DutyVar1, 13, 10] ' Send text followed by carriage return and linefeed
#ENDIF

Main:
   ADCIN 1, adval
   if adval <> oldDutyVar1 then
      oldDutyVar1 = adval
      DutyVar1 = adval

      #IFDEF USE_LCD_FOR_DEBUG
         HSEROUT [LCD_INST, LCD_CLR, LCD_L1]
         HSEROUT ["DutyVar1=", DEC DutyVar1, "  ", 13, 10] ' Send text followed by carriage return and linefeed
      #ENDIF
   EndIf
   Pause 100
Goto Main