16F684 Basic Functionality

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- 25th September 2009, 15:41
munromh

16F684 Basic Functionality

Having a few problems getting some basic functions to work properly on a 16F684, not sure if I can see the forest through the trees now. Basically I can't get the toggle function to work, works fine if I set a pin to 1 then 0. Also, if I have a SEROUT pin on the same Port as a Pin I'm manually toggling the SEROUT works but the toggle doesn't, move the SEROUT to a different port and all's fine:

Code:

'16f684 DEFINE OSC 8 'Oscillator speed in MHz OSCCON = %01110111 'Page 20 ANSEL = %00000000 TRISA = %00000000 TRISC = %00000000 PortA = %00000000 PortC = %00000000 WPUA = %00000000 CMCON0 = %00000000 ADCON0 = %00000000 ADCON1 = %00000000 Heart_Beat_LED Var portC.1 'Output pin to LED for Heart Beat indication, Low is on. Heart_Beat_LED = 0 Terminal_TX var PortC.2 'Output pin to the dumb terminal or PC program on port C Start: 'Uncomment subroutine 1, 2, or 3 'Goto Subroutine_1 'Goto Subroutine_2 'Goto Subroutine_3 goto Start Subroutine_1: 'This works. Heart_Beat_LED = 1 Pause 1000 Heart_Beat_LED = 0 Pause 1000 Goto Start Subroutine_2: 'Pin is "low" and can be seen cycling between 125mV and 75mV on a scope. 'both serial out's seen on terminal. 'If I move the Terminal_TX to PortA it works. Heart_Beat_LED = 1 serout Terminal_TX,6,["1-Heart_Beat_LED",13,10] Pause 1000 Heart_Beat_LED = 0 serout Terminal_TX,6,["2-Heart_Beat_LED",13,10] Pause 1000 Goto Start Subroutine_3: 'Doesn't work Toggle Heart_Beat_LED Pause 1000 Goto Start
- 25th September 2009, 16:48
Kamikaze47

Strange. I have seen toggle do strange things before but cant remember what the problem was.

Out of interest, does it work if you use the following instead of toggle:

IF Heart_Beat_LED=0 THEN
Heart_Beat_LED=1
ELSE
Heart_Beat_LED=0
ENDIF

PAUSE 1000
- 25th September 2009, 18:57
Archangel

analog blues perhaps

cmcon0 = 7 'Comparators off. CxIN pins are configured as<b> digital I/O</b>
cmcon0 = 0'Comparators off. CxIN pins are configured as analog
- 25th September 2009, 19:02
munromh

Quote:

Originally Posted by Kamikaze47

Strange. I have seen toggle do strange things before but cant remember what the problem was.

Me too.

Quote:

IF Heart_Beat_LED=0 THEN
Heart_Beat_LED=1
ELSE
Heart_Beat_LED=0
ENDIF

PAUSE 1000

Nada, doesn't work. Pin stays high, don't see any change with a scope. It always sees Heart_Beat_LED = 0.

Interestingly enough, which I left off the earlier post, if I write:

Code:

serout Terminal_TX,6,["1-Heart_Beat_LED = ",#Heart_Beat_LED,13,10] serout Terminal_TX,6,["2-Heart_Beat_LED = ",#Heart_Beat_LED,13,10]

The value remains zero in each SEROUT.
- 28th September 2009, 11:15
munromh

Quote:

Originally Posted by Joe S.

cmcon0 = 7 'Comparators off. CxIN pins are configured as<b> digital I/O</b>

Thanks Joe S., I should know better. All is fine now.
- 30th September 2009, 16:54
mike1939

configure 16f690 for xtal osc

Can't quite find the right place to ask this but anyway.....please bear with me..........
Have scoured the 306 pages of the data sheet and still can't make my
PIC16F690 oscillate at 12MHz. In PBP how do I configure it for ext crystal?
Desperate, why do I find it so difficult? I'm only 70 yrs old.
Cheers
- 30th September 2009, 20:28
Melanie

External Oscillator selection is performed from the CONFIGURATION BITS of this PIC.

See section 14 of the Datasheet (and section 3 if you're really bored)... mine's only got 304 pages, so you must have the 'Professionals' copy.

Use your programmer to select HS OSC manually at program time if you are connecting a 12MHz Xtal.

Alternatively, embed the appropriate device CONFIG into your program... see for example...

http://www.picbasic.co.uk/forum/showthread.php?t=543

Finally, don't forget to include DEFINE OSC 12 somewhere at the top of your program to tell PBP that you're running at 12MHz, otherwise it will continue to think you're at 4MHz (the default).