Clock output

ttbuddy · Mar 5, 2009

How to get the clock output from the PIC to a clock input for a shift register? Thanks

Nigel Goodwin · Mar 5, 2009

ttbuddy said:
How to get the clock output from the PIC to a clock input for a shift register? Thanks

A piece of wire or a PCB track?.

Mikebits · Mar 5, 2009

Nigel Goodwin said:
A piece of wire or a PCB track?.

lol... snicker...too funny

ttbuddy · Mar 5, 2009

Nigel Goodwin said:
A piece of wire or a PCB track?.

what do you mean by that? I din use PCB .....
I am using 16F88

ericgibbs · Mar 5, 2009

ttbuddy said:
what do you mean by that? I din use PCB .....
I am using 16F88

hi tt,
Are you using the 16F88 internal clock or an external crystal.?

ttbuddy · Mar 5, 2009

ericgibbs said:
hi tt,
Are you using the 16F88 internal clock or an external crystal.?

Internal 4MHz clock

ericgibbs · Mar 5, 2009

ttbuddy said:
Internal 4MHz clock

hi,
Ive had a quick look thru the 16F88 datasheet, I dont think can bring out the internal clock.?

EDIT:
Look at Section 4:1 of datasheet, it says

ttbuddy · Mar 5, 2009

ericgibbs said:
hi,
Ive had a quick look thru the 16F88 datasheet, I dont think can bring out the internal clock.?

even with programming? which means i cant handle with shift register? sigh ..

ericgibbs · Mar 5, 2009

ttbuddy said:
even with programming? which means i cant handle with shift register? sigh ..

Look at my EDIT ref INTIO1

Recheck this image.? Its says it can be done. Prog INTOSC/FOSC2,1,0 to suit and check the osc output with a scope.

ttbuddy · Mar 5, 2009

I'd first define this:

Code:

	ifdef	__16F88
 __config _CONFIG1,_BODEN_OFF&_WDT_OFF&_LVP_OFF&_MCLR_OFF&_PWRTE_ON&_INTRC_IO

so output will be at RA6?
How to program it? ASM newbie here.

ericgibbs · Mar 5, 2009

ttbuddy said:
I'd first define this:

Code:

ifdef __16F88 __config _CONFIG1,_BODEN_OFF&_WDT_OFF&_LVP_OFF&_MCLR_OFF&_PWRTE_ON&_INTRC_IO

so output will be at RA6?
How to program it? ASM newbie here.

hi,
Ive looked at the 16F88.inc file in microchip for the CONFIG1 it says:

_INTRC_CLKOUT

_CONFIG1,_BODEN_OFF&_WDT_OFF&_LVP_OFF&_MCLR_OFF&_PWRTE_ON&_INTRC_CLKOUT

would do it.

EDIT: for reference

Code:

;Configuration Byte 1 Options
_CP_ALL                      EQU     H'1FFF'
_CP_OFF	                     EQU     H'3FFF'
_CCP1_RB0		    		 EQU     H'3FFF'
_CCP1_RB3                    EQU     H'2FFF'
_DEBUG_OFF                   EQU     H'3FFF'
_DEBUG_ON                    EQU     H'37FF'
_WRT_PROTECT_OFF             EQU     H'3FFF'	;No program memory write protection
_WRT_PROTECT_256             EQU     H'3DFF'	;First 256 program memory protected
_WRT_PROTECT_2048            EQU     H'3BFF'	;First 2048 program memory protected
_WRT_PROTECT_ALL             EQU     H'39FF'	;All of program memory protected
_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'

;Configuration Byte 2 Options
_IESO_ON                     EQU     H'3FFF'
_IESO_OFF                    EQU     H'3FFD'
_FCMEN_ON                    EQU     H'3FFF'
_FCMEN_OFF                   EQU     H'3FFE'

edeca · Mar 5, 2009

ttbuddy said:
How to get the clock output from the PIC to a clock input for a shift register? Thanks

Do you need to use the 4Mhz clock output? Or can you use a spare output pin and generate your own 'clock' (i.e. high, NOP, low) when you want to clock in data?

ttbuddy · Mar 5, 2009

ericgibbs said:

hi,
Ive looked at the 16F88.inc file in microchip for the CONFIG1 it says:

_INTRC_CLKOUT

_CONFIG1,_BODEN_OFF&_WDT_OFF&_LVP_OFF&_MCLR_OFF&_PWRTE_ON&_INTRC_CLKOUT

would do it.

EDIT: for reference

Code:

;Configuration Byte 1 Options
_CP_ALL                      EQU     H'1FFF'
_CP_OFF	                     EQU     H'3FFF'
_CCP1_RB0		    		 EQU     H'3FFF'
_CCP1_RB3                    EQU     H'2FFF'
_DEBUG_OFF                   EQU     H'3FFF'
_DEBUG_ON                    EQU     H'37FF'
_WRT_PROTECT_OFF             EQU     H'3FFF'	;No program memory write protection
_WRT_PROTECT_256             EQU     H'3DFF'	;First 256 program memory protected
_WRT_PROTECT_2048            EQU     H'3BFF'	;First 2048 program memory protected
_WRT_PROTECT_ALL             EQU     H'39FF'	;All of program memory protected
_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'

;Configuration Byte 2 Options
_IESO_ON                     EQU     H'3FFF'
_IESO_OFF                    EQU     H'3FFD'
_FCMEN_ON                    EQU     H'3FFF'
_FCMEN_OFF                   EQU     H'3FFE'

Thanks. thumbs up!

ttbuddy · Mar 5, 2009

edeca said:
Do you need to use the 4Mhz clock output? Or can you use a spare output pin and generate your own 'clock' (i.e. high, NOP, low) when you want to clock in data?

as i just want them synchronizaed

Nigel Goodwin · Mar 5, 2009

ttbuddy said:
as i just want them synchronizaed

Sorry, but it sounds like you don't have a clue what you're doing?.

edeca · Mar 5, 2009

ttbuddy said:
as i just want them synchronizaed

Unless you're writing to the shift register at a speed of 4Mhz (you're not!) you don't need a 4Mhz clock. The clock on a shift register is used when you want it to do something. You don't want it to do something that many times a second!

Perhaps if you post a circuit diagram or an overview of your circuit we can help. But the solution is probably going to be using a spare output pin and generating the pulse you need in code.

ttbuddy · Mar 5, 2009

edeca said:
Unless you're writing to the shift register at a speed of 4Mhz (you're not!) you don't need a 4Mhz clock. The clock on a shift register is used when you want it to do something. You don't want it to do something that many times a second!

Perhaps if you post a circuit diagram or an overview of your circuit we can help. But the solution is probably going to be using a spare output pin and generating the pulse you need in code.

Here is the schematic:
**broken link removed**
Well, I just want the parallel output to be converted as serial only. so thts y i choose shift register.

I do have another option to use assembly language but i am numb on that. Unless someone n guide me to have one particular register to serially output the data, well this method is much more preferable.

edeca · Mar 5, 2009

ttbuddy said:
Well, I just want the parallel output to be converted as serial only. so thts y i choose shift register.

Which parallel output? If you want to use the LCD with less wires, check both of the following:

2-Wire PIC LCD Interface by Myke Predko
**broken link removed**

edeca · Mar 5, 2009

Oh and whilst this might be the only useful thing I ever contribute on these forums, your /MCLR pin is tied low. That wont work.

Pull it up to VDD with a resistor and switch it to GND if you need a reset switch.

ttbuddy · Mar 5, 2009

edeca said:
Oh and whilst this might be the only useful thing I ever contribute on these forums, your /MCLR pin is tied low. That wont work.

Pull it up to VDD with a resistor and switch it to GND if you need a reset switch.

well, i din use that. So i OFF my MCLR for that.
The 4 parallel is the one connected to the DB4 ~ 7.
Do you know assembly well?

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