External clock on 16f819 problem.

**Demon** · - 22nd January 2012, 20:54

Originally Posted by Dave

Robert, Havent you ever ran a PIC from an external oscillator before? ...

Always.

Originally Posted by Dave

...You only need 1 pin for the input. ...

Not wired like this:

Name: PIC schematic.JPG
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Robert

**Dave** · - 22nd January 2012, 23:15

No Robert, Like this:
Name: Ext Osc.JPG
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**Demon** · - 22nd January 2012, 23:43

Wouldn't that need a CONFIG fuse?

Dave, do you have an example from one of your programs?

Robert

EDIT: These are the available fuses for a 16F819:

Code:

_CP_ALL                      EQU     H'1FFF'
_CP_OFF	                     EQU     H'3FFF'
_CCP1_RB2		     EQU     H'3FFF'
_CCP1_RB3                    EQU     H'2FFF'
_DEBUG_OFF                   EQU     H'3FFF'
_DEBUG_ON                    EQU     H'37FF'
_WRT_ENABLE_OFF              EQU     H'3FFF'
_WRT_ENABLE_512              EQU     H'3DFF'
_WRT_ENABLE_1024             EQU     H'3BFF'
_WRT_ENABLE_1536             EQU     H'39FF'
_CPD_ON                      EQU     H'3EFF'
_CPD_OFF                     EQU     H'3FFF'
_LVP_ON                      EQU     H'3FFF'
_LVP_OFF                     EQU     H'3F7F'
_BODEN_ON                    EQU     H'3FFF'
_BODEN_OFF                   EQU     H'3FBF'
_MCLR_ON		     EQU     H'3FFF'
_MCLR_OFF                    EQU     H'3FDF'
_PWRTE_OFF                   EQU     H'3FFF'
_PWRTE_ON                    EQU     H'3FF7'
_WDT_ON                      EQU     H'3FFF'
_WDT_OFF                     EQU     H'3FFB'
_EXTRC_CLKOUT		     EQU     H'3FFF'
_EXTRC_IO		     EQU     H'3FFE'
_INTRC_CLKOUT                EQU     H'3FFD'
_INTRC_IO		     EQU     H'3FFC'
_EXTCLK			     EQU     H'3FEF'
_HS_OSC                      EQU     H'3FEE'
_XT_OSC                      EQU     H'3FED'
_LP_OSC                      EQU     H'3FEC'

And these are the default settings (PM and MPASM):

Code:

        device  pic16F819, hs_osc, wdt_on, pwrt_on, lvp_off, protect_off
        ...    else
        ...        __config _HS_OSC & _WDT_ON & _PWRTE_ON & _LVP_OFF & _CP_OFF

**tasmod** · - 23rd January 2012, 11:14

To all intents and purposes a clock and oscillator are one and the same.

The answer lies at the end of the fuses list 4th from bottom _EXTCLK needs setting as my programmer defaults to standard inc setting.

This is what I need :

_LVP_OFF & _CP_OFF & _BODEN_ON & _MCLR_OFF & _PWRTE_ON & _WDT_OFF & _EXTCLK & _DEBUG_OFF & _WRT_ENABLE_OFF & _CPD_OFF & _CCP1_RB3

**tasmod** · - 23rd January 2012, 11:22

Hmm, I posted another reply but it vanished into the ether !

**tasmod** · - 23rd January 2012, 13:07

OK, changing the INC file and putting that line in did the trick. Seems my programmer options don't work it always goes back to the standard INC, modifying that worked.

The LCD now responds in a single line format but I seem to be screwed up with the ADCON TRIS etc. No surprise there then.

I'll post the code once I have it from the other computer.

**tasmod** · - 23rd January 2012, 16:33

OK, this is the test code. Just trying to reproduce characters.

The IN/OUTS ADC etc are there but there's no code to run them in this version.

The ADCON1 register is setup and the LCD displays one line but I need to study up the rest TRIS etc.

Code:

'****************************************************************
'*  Name    :                                      *
'*  Author  : Rob Lane                                          *
'*  Notice  :                                                   *
'*          :                                                   *
'*  Date    : 13/01/2012                                        *
'*  Version : 1.0                                               *
'*  Notes   : Using 16f819                                      *
'*                                                              *
'****************************************************************


LCD_DB4    VAR PORTB.4 
LCD_DB5    VAR PORTB.5 
LCD_DB6    VAR PORTB.2 
LCD_DB7    VAR PORTB.7 
LCD_RS     VAR PORTA.2 
LCD_E      VAR PORTA.3 

LCD_Lines  CON 2 ' # of Lines on LCD, 1 or 2 (Note: use 2 for 4 lines) 
LCD_DATAUS CON 50 ' Data delay time in us 
LCD_COMMANDUS CON 2000 ' Command delay time in us
clear

  ' Define ADCIN parameters
Define	ADC_BITS	10	' Set number of bits in result
Define	ADC_CLOCK	0	' Set clock source (Fosc/2)
Define	ADC_SAMPLEUS	50	' Set sampling time in uS

INCLUDE "LCD_AnyPin.pbp" ; *** Include MUST be AFTER LCD Pin assignments ****

'setup the custom characters
LCDOUT  $FE,$40,$01,$01,$01,$01,$01,$01,$01,$01  ' Cust Char #0 
LCDOUT  $FE,$48,$1F,$11,$11,$11,$11,$11,$11,$11  ' Cust Char #1  
LCDOUT  $FE,$50,$1F,$10,$10,$10,$10,$10,$10,$1F  ' Cust Char #2  
LCDOUT  $FE,$58,$01,$01,$01,$01,$01,$01,$01,$1F  ' Cust Char #3  
LCDOUT  $FE,$60,$1F,$11,$11,$11,$11,$11,$11,$1F  ' Cust Char #4  
LCDOUT  $FE,$68,$11,$11,$11,$11,$11,$11,$11,$1F  ' Cust Char #5  
LCDOUT  $FE,$70,$1F,$01,$01,$01,$01,$01,$01,$1F  ' Cust Char #6  
LCDOUT  $FE,$78,$1F,$01,$01,$01,$01,$01,$01,$01  ' Cust Char #7 

'setup the THICKER custom characters
'LCDOUT  $FE,$40,$03,$03,$03,$03,$03,$03,$03,$03  ' Cust Char #0 
'LCDOUT  $FE,$48,$1F,$1F,$1B,$1B,$1B,$1B,$1B,$1B  ' Cust Char #1  
'LCDOUT  $FE,$50,$1F,$1F,$18,$18,$18,$18,$1F,$1F  ' Cust Char #2  
'LCDOUT  $FE,$58,$03,$03,$03,$03,$03,$03,$1F,$1F  ' Cust Char #3  
'LCDOUT  $FE,$60,$1F,$1F,$1B,$1B,$1B,$1B,$1F,$1F  ' Cust Char #4  
'LCDOUT  $FE,$68,$1B,$1B,$1B,$1B,$1B,$1B,$1F,$1F  ' Cust Char #5  
'LCDOUT  $FE,$70,$1F,$1F,$03,$03,$03,$03,$1F,$1F  ' Cust Char #6  
'LCDOUT  $FE,$78,$1F,$1F,$03,$03,$03,$03,$03,$03  ' Cust Char #7 

nPos  var byte
nDig  var byte
in_count  var word
tr_out  var word
batt_volt  VAR BYTE

batt_adc var porta.0
freq_in var portb.6
freq_lockout var portb.3

'TRISA=%10001101
'TRISB=%01000000
'ADCON0=%00000000
ADCON1=%10001110   

LOW PortB.0  		 ;r/w lcd line

'CONFIGURE DISPLAY 
pause 1000
ln1 con $80
ln2 con $C0
CS  con 1
pause 500
LCDOUT $FE,1

lcdout $fe, CS            ' Clear screen

main:  
	nDig=1 : npos=0 : gosub displaydigit  
	nDig=2 : npos=1 : gosub displaydigit
    nDig=3 : npos=2 : gosub displaydigit
    nDig=4 : npos=3 : gosub displaydigit
    lcdout $FE,$80+6,"Test" 
   		
goto main
  

displaydigit:
if ndig=0 then gosub zero
if ndig=1 then gosub One
if ndig=2 then gosub Two
if ndig=3 then gosub Three
if ndig=4 then gosub Four
if ndig=5 then gosub Five
if ndig=6 then gosub Six
if ndig=7 then gosub Seven
if ndig=8 then gosub Eight
if ndig=9 then gosub nine
return
   	
Zero:
	LCDOUT $FE,$80+nPos,1
	LCDOUT $FE,$C0+nPos,5
return

One:
	LCDOUT $FE,$80+nPos,0
	LCDOUT $FE,$C0+nPos,0
return

Two:
	LCDOUT $FE,$80+nPos,7
	LCDOUT $FE,$C0+nPos,2
return

Three:
	LCDOUT $FE,$80+nPos,6
	LCDOUT $FE,$C0+nPos,3
return

Four:
	LCDOUT $FE,$80+nPos,5
	LCDOUT $FE,$C0+nPos,0
return

Five:
	LCDOUT $FE,$80+nPos,2
	LCDOUT $FE,$C0+nPos,3
return

Six:
	LCDOUT $FE,$80+nPos,2
	LCDOUT $FE,$C0+nPos,5
return

Seven:
	LCDOUT $FE,$80+nPos,7
	LCDOUT $FE,$C0+nPos,0
return

Eight:
	LCDOUT $FE,$80+nPos,4
	LCDOUT $FE,$C0+nPos,5
return

Nine:
	LCDOUT $FE,$80+nPos,4
	LCDOUT $FE,$C0+nPos,3
return

    

end

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