Serout2 on LCD Shows Junk Characters

**RossWaddell** · - 14th January 2013, 00:08

I'm trying to work out whether the code below is accurately producing 0-255 values for the ADCIN command which I'm then using in conjunction with Darrel's SPWM_Int.bas, but I can't tell because my Scott Edwards Electronics ILM-216 serial LCD just shows gobbledy-gook. I've jumpered pins 6 & 8 on the LCD to get 9600bps but it's no better than the default 2600 baud.

Can anyone help me out? I bought this serial LCD as my previous one was a parallel one which uses too many pins but it's not much good to me if it can't help me debug.

Scott Edwards Electronics data sheet for the ILM-216 can be seen here.

Code:

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

' RA0                        -> Middle arm of trim pot
' RC0                        -> LED1
' RC1                        -> LED2
' RC2                        -> LED3
' RC4                        -> Serial LCD output

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)

' ***************************************************************
' 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.0 (AN0) for ADCIN (trim pot reading)
ANSELA   = %00000001        ; Analog on PORTA.0 (AN0) only
TRISA    = %00000001        ; Input on PORTA.0 (AN0) 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
    serout2 LCD_PIN, LCD_BAUD, LCD_PACE, [LCD_INST, LCD_CLR]     ; clear screen
    pause 5
    serout2 LCD_PIN, LCD_BAUD, LCD_PACE, ["DutyVar1:", DEC DutyVar1, "         "]
#ENDIF

Main:
   ADCIN 0, adval
   if adval <> oldDutyVar1 then
      oldDutyVar1 = adval
      DutyVar1 = adval

      #IFDEF USE_LCD_FOR_DEBUG
          serout2 LCD_PIN, LCD_BAUD, LCD_PACE, [LCD_INST, LCD_CLR]     ; clear screen
          pause 5
          serout2 LCD_PIN, LCD_BAUD, LCD_PACE, ["DutyVar1:", DEC DutyVar1, "         "]
      #ENDIF
   EndIf
   Pause 100
Goto Main

**Darrel Taylor** · - 14th January 2013, 01:47

Ross,

You can't use software timed serial routines when using interrupts.

You will need to use the USART and HSEROUT.

**gadelhas** · - 14th January 2013, 01:48

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** · - 14th January 2013, 02:13

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

**gadelhas** · - 14th January 2013, 02:41

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** · - 14th January 2013, 02:52

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

Code:

'****************************************************************
'*  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

Code:

APFCON0.2 = 1               ; Tx on RA0

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

**gadelhas** · - 14th January 2013, 02:59

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** · - 14th January 2013, 05:07

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

Add this setting ...

Code:

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

**RossWaddell** · - 14th January 2013, 14:03

Originally Posted by Darrel Taylor

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

Add this setting ...

Code:

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).

Code:

#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

**Darrel Taylor** · - 14th January 2013, 15:48

HSEROUT [LCD_INST, LCD_CLR, LCD_L1]

You need at least a 2mS pause after the clear screen command.
Then you need another LCD_INST before the LCD_L1.
Or just leave out the LCD_L1 since the clear screen leaves the cursor on line 1.

**RossWaddell** · - 14th January 2013, 16:51

I have a 5ms pause before the Main loop, but I think it's irrelevant since the ADCIN gets a value which is immediately different than the set value for DutyVar1 (set to 0 earlier in the code) and hence it goes straight into the IF block.

I'll add a 5ms pause in the IF block, too. And remove the LCD_L1 if it's not needed.

Thanks again, Darrel!

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