Extreme Noobie question 12F675

[paul borgmeier]

Hi Jeff,

I have not used Pic Basic Compiler for almost 10 years but here are some comments and items to check/change to get you going.

SYMBOL ANSEL = $9F '$19 IS ANSEL REGISTER 
POKE ANSEL, 0 'MAKE PIN DIGITAL, NOT ANALOG

this looks good except your comment is for CMCON not ANSEL (see below)

SYMBOL ADCON0 = $1F 'TURN OFF A/D ON PIN4. (DEFAULT IS ON)
POKE ADCON0, 254 '$1F IS ADDR OF A/D REGISTER. 10011111 (7)

you do not need to fiddle with ADCON0 unless you want to use the A2D module. You should leave these two lines out. As it stands now, these two lines set up the A2D to acquire AN3 using a reference voltage on pin GP1, which might be messing you up. The pins do default to analog but changing them to digital is accomplished with ANSEL and CMCON.


You need to disable the comparators so add something like this

SYMBOL CMCON = $19 '$19 IS CMCON  REGISTER 
POKE CMCON, 7 'MAKE PIN DIGITAL, NOT ANALOG

SYMBOL TRISA = $85 'SETUP PINS DATA DIR I/O
POKE TRISA, 255 'MAKE DATA I/O GP0 AN OUTPUT, GP1 AN INPUT 
'AND MAKE GP1 AN INPUT (ALL OTHERS ARE OUTS)

Here the poke 255 is actually making everything inputs. If you want everything to be inputs except GP0, then poke 254

symbol PORTA = $05 '$05 IS OUTPUT DATA REGISTER
POKE PORTA, 0 'TURN OFF ALL BITS

turns off all outputs so okay

Loop1: PEEK PORTA, BIT0 'COPY PORTA REG, PUT IN VARIABLE B0

you need to peek porta into a byte sized variable. Try PEEK PORTA, B0 as noted in your comment

IF BIT0 = 1 THEN LOOP1 'WHEN BUTTON IS PUSHED, INPUT GOES LOW

this does check bit 0 of B0 but you wanted GP0 to be an output? Maybe you want to check the bit where your switch is connected.?

loop2: High 0 'Turn on LED connected to GP0
Pause 500 'Delay for .5 seconds

Low 0 'Turn off LED connected to GP0
Pause 500 'Delay for .5 seconds

Goto loop2 'Go back to loop and blink LED forever

this trap looks good.


One last comments - Ski is correct, it is strange to rename the GPIO port to PORTA. Consider changing all PORTA refs above to GPIO. The same goes for TRISA - change to TRISIO

reply back with progress for more help

[F1CHF]

Hello
First, I have made a search on that PIC but I didn't find any answer on the following questions :

1/ Am I right if I say that the VSS and VDD pins are not in the same way than the well known 16F84 ?
we must make an adaptator to use a JDM programmer and having RB6 (pin 12) and RB7 (pin 13) pins on pin 7 and 6 on the 12F675 (assuming that we reverse VSS and VDD) and take pin 4 of the 16F84 to pin 4 on the 12F675 ! hope it is clear !

2/ we must read first the 12F675 to store oscal and bandgap datas ?

3/ we must play with CMCOM and Ansel command to have Digital port instead of analog status a power on time. (same story than for 16F628 or 16F88)

4/ we must forget PORTA and use GPIO to declare activ pins ?

5/ we must modify HEX file to feed oscal and bangap datas before programming ?

if I can find the famous BLINK.BAS program for 12F675, I will save time ...

what else ? nespresso pub ?

thanks

Francois