Hi Josef,

>after about 2 days of debugging I cannot find any more bugs, but the device
>is not working yet. Finally I turned it into a LED blinking circuit, but it
>looks, that the pins do not even change to outputs. Have I done something
>stupid or should I search the hardware? The config equals 0xffa - MCLR
>enabled, no CP, no WDT, internal RC oscillator, and yes, I checked the MCLR
>voltage, it is +5V. This is my first project using 12C509, so I may be
>overlooking something really trivial. The listing (line numbers deleted)
>follows. TIA, and if possible, include cc to snail@iol.cz, so that don't
>have to wait for the digest.

Have you simulated your code?  How do you know that the pins aren't changing
to outputs?

I'm asking these questions because I can see a very big problem in the code...

You have the delay loop:

L0:     DECFSZ  CNT0,F
        GOTO    L0
        DECFSZ  CNT0,F
        GOTO    L0

Which will never be exited.

I think you want to have the code:

L0:     DECFSZ  CNT0,F
        GOTO    L0
        DECFSZ  CNT1,F    <-- Note the Change
        GOTO    L0

Which will delay about a fifth of a second (running at 4 MHz).

In your code, after the first "DECFSZ CNTO,F" loop exits (ie "CNT0" will be
equal to zero), the next "DECFSZ CNT0,F" instruction will change it to
0x0FF, jump back to "LO" and you will decrement CNT0 to Zero, decrement it
again to 0x0FF, and so on forever, never leaving the loop.


It is especially important for your first programs to simulate them until
you are absolutely sure they work properly.

When you said the program isn't running, how do you know that?  If you're
checking them with a DMM, you might be seeing 0 Volts, which doesn't tell
you anything.

Invest in a logic anayzer ($20 here in Canada) and check them - Radio Shack
actually has a decent one for this price.  You should see that they're set
either high or low (and not high impedance which has neither light on).

Good luck,

myke


>LOC  OBJECT CODE     SOURCE TEXT
>  VALUE
>                             LIST P=12C509,R=DEC
>                             INCLUDE <P12C509.INC>
><snip>
>                             INCLUDE <Q12C509.INC>
><snip>
>                             INCLUDE <STDMAC.INC>
>                             LIST
><snip>
>                             CBLOCK  __GPRAM
>  00000007                           CNT0, CNT1
>                             ENDC
>
>  000F4240           CLOCK:  EQU     D'1000000'
>  00000960           BAUD:   EQU     D'2400'
>
>0000                         ORG     0
>0000 0C00                    MOVLW   B'00000000'
>0001 0006                    TRIS    GPIO
>0002 02E7            L0:     DECFSZ  CNT0,F
>0003 0A02                    GOTO    L0
>0004 02E7                    DECFSZ  CNT0,F
>0005 0A02                    GOTO    L0
>0006 0CFF                    MOVLW   0XFF
>0007 01A6                    XORWF   GPIO,F
>0008 0A02                    GOTO    L0
>
>03FF                         ORG     0X3FF
>Warning[220]: Address exceeds maximum range for this processor.
>03FF 0C70                    MOVLW   0X70
>                             END
>
>

Check out the "Handbook of Microcontrollers" as a reference for embedded
microcontrollers including information on the Intel 8051, Motorola 68HC05,
Microchip PICMicro, Atmel AVR and Parallax Basic Stamp:

http://www.myke.com/#MCUHand


Hunter S. Thompson's quest for the American Dream, this week in the Book Room.

http://www.myke.com/Book_Room/book1a.htm