External clock on 16f819 problem.

[Dave]

Robert, Havent you ever ran a PIC from an external oscillator before? You only need 1 pin for the input. That frees up another pin for some external use by the designer.

[Demon]

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

Always.

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

Not wired like this:



Robert

[Dave]

No Robert, Like this:

[Demon]

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:

_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):

        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]

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]

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

[tasmod]

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.

[rsocor01]

Robert, Havent you ever ran a PIC from an external oscillator before? You only need 1 pin for the input.

What you posted is an external clock input, like the title says. That's not really an external oscillator.