GPIO.2 of 12F509 doesn't work.

At the first time of using the 12F509 instead of the 12F629 I discovered a problem.
@ device INTRC_OSC,MCLR_OFF
'cmcon=7 'for the 12F629 only
trisio=%001000
GPIO=%000000
GPIO=%110111
Pause 1000
GPIO=%000000
Stop

All 5 outputs of the 629 went high for 1 second.
The 509 GPIO.2 doesn't do anything, GPIO.0, 1, 4 and 5 went high for one second.
Both PIC's are tested on the same PCB.
What could be wrong or what do I do wrong?
I use PBP2.46, MPLab7.1 and PICStart Plus.

Try this... and tell us if it works...

Code:

---

        TRISIO=%00001000
Loop:       
        High GPIO.2
        Pause 1000
        Low GPIO.2
        Pause 1000
        Goto Loop

        end

---

Quote:

---

Originally Posted by Melanie

Try this... and tell us if it works...

Code:

---

        TRISIO=%00001000
Loop:       
        High GPIO.2
        Pause 1000
        Low GPIO.2
        Pause 1000
        Goto Loop

        end

---

---

Hello Melanie,
I tried and: GPIO.2 stays low, GPIO.0 , 1 , 4 and 5 are high.
If I put GPIO=%00000000 after Trisio all outputs are low.
I took a new PIC509 and the same happens, very strange.
The 629 GPIO.2 works fine.....

Datasheet, Datasheet, Datasheet!!!!!

Really.... you gotta get this tatooed in some prominent place...

Walk with me on this one...

GPIO.2 is also the T0CKI pin...

Table 6-1 on Page 34 Reference Note (3) at the bottom states "The TRIS of the T0CKI pin is over-ridden when T0CKS=1". There's also a great-big NOTE to this effect at the top of Page 22!

T0CKS is part of the OPTION REGISTER.

See Register 4-3 on Page 22 and cross-reference this with Table 7-3 (Reset Conditions) on Page 44... you will note that this register bit is set to '1' on Power-up, therefore TRISIO is over-ridden...

So set OPTION_REG.5=0 before your TRISIO statement.

Thanks Melanie,

It's all working now.
Your explanation was very clear.
I understand now why it didn't work, but I couldn't find it out by myself.

Thanks a lot.