Surprising 16F628 / 20

[Acetronics2]

I tried to program a ... simple stupid blinking light ... and it doesn't work ... as it should !!!

'******************************************************************************
'Configuration
'******************************************************************************

@	__CONFIG  _BODEN_ON &_CP_OFF & _PWRTE_ON & _WDT_ON & _LVP_OFF & _MCLRE_ON  & _INTRC_OSC_CLKOUT

	CMCON	= 7
	VRCON	= 0	

...

'*****************************************************************************
'Initialisation des ports
'*****************************************************************************

	PORTA   = 0
	PORTB   = 0

	TRISA = %00000111
	TRISB = %00000000

...

'******************************************************************************
oubli: ' Boucle d'arret si oubli cavalier
'******************************************************************************

	PORTB.0 = 1
	PAUSE 200
	PORTB.0 = 0
	PAUSE 200

	GOTO Oubli

Doesn't work


But That snippet works fine :

( same as previous )

...

'******************************************************************************
oubli: ' Boucle d'arret si oubli cavalier
'******************************************************************************

	HIGH PORTB.0 
	PAUSE 200
	LOW  PORTB.0
	PAUSE 200

	GOTO Oubli

The load on PORTB.0 is a simple LED drawing 12 mA ...

Has someone an idea ???

Alain

[Jerson]

Alain

What do you mean - Doesn't work. Can you elaborate your statement? Is the LED always on/off?
The ellipses before Oubli - is there something that modifies your TRISB in there?

When you do HIGH / LOW to a pin, PBP also writes the TRIS bit for the pin to the direction you need.

[Acetronics2]

Hi, Jerson

Halas, there are no TRIS mods in the whole program ( including PbP commands ).

Just reading 3 EEPROM locations to verify if the device is ( application ) programmed or not.

add to that a BUTTON command to verify, if EEPROM unprogrammed, if the programming jumper has been inserted ...

	TRISA = %00000111
	TRISB = %00000000


'******************************************************************************
'Lecture des valeurs en EEPROM
'******************************************************************************


	READ 1,dureeprog
	READ 2,side
	READ 3,neutre

	IF ( neutre <> 255 ) AND( dureeprog <> 255 ) THEN start

'******************************************************************************
' Vérification Présence Cavalier si première programmation
'******************************************************************************

	Delay = 0
	BUTTON ModProg,0,255,0,delay,1,Mesurepro

'******************************************************************************
oubli: ' Boucle d'arret si oubli cavalier
'******************************************************************************
...

as you can see, I just had cut those "unsignificant" lines.

I've also verified the ASM lines, but nothing noticeable ...



the strange thing is I had added those lines just past TRISA and TRISB, to verify PortB ( same LED load + 270 Ohms on each PortB output ) ...

'******************************************************************************
'Verification PORTB
'******************************************************************************

'	FOR I = 0 to 7
'	
'		PORTB.0[i] = 1
'		PAUSE 300
'		
'	NEXT I
'	
'	FOR I = 7 to 0 Step -1
'	
'		PORTB.0[i] = 0
'		PAUSE 300
'		
'	NEXT I

and it worked well ...


I've already seen Port outputs not working , like here, but it was when driving large capacitive loads ( 3.5 µF between output and ground !!! ).

Solution had been using HIGH and LOW ... like here.


But, Here, it's the first time I see that with LEDs as loads ...

so, I know what to do ... but really don't understand why !!!

Alain

[skimask]

Read-Modify-Write issues?

[Jerson]

Alain

I'm not really sure what to make of it. What is the state of LED? On or Off?

[Acetronics2]

Hi, Jerson

PORTB.0 = 1 : Led do not work

HIGH PORTB.0 : Led works fine


Hi, Ski

I verified the ASM ... doesn't read anything at all ,here.

PORTB.0 =  BSF PORTB,0

HIGH PORTB.0 =  BSF PORTB,0
                       BSF STATUS, 5
                       BCF PORTB,0

                    **Next ASM command** MOVLW 0xC8 ( Pause duration )

                       BCF STATUS, 5

so, the only "surprising thing" is it writes PAUSE duration in W while addressing page 1 ... but I do not think it should cause any trouble ... I suppose it works like that not to toggle Page twice, if staying on page 1 !

I'll try the program with XTAL clock ( it's the first time I use INTRC with this snippet ...) ever has worked well till yesterday ... just to see.

Alain