Need help using 32k watch crystal as main oscilator on 16F19346

[David Stephenson]

If you want the whole thing to work at 32k then
FEXOSC=LP
If you just want to do timing then hook up your TIMER1 to SOCS
it involves setting some registers (I do it the hard way just to be safe)
t1con=b'10111101' 'timer1 8:1
intcon.6=1 'peripheral interrupt enable
pie1.0=1 'timer1 overflow interrupt enable
t1gcon.7=0 'timer1 runs continuously.
I find this is good for low power work as you can put the chip into SLEEP mode and TIMER1 still runs and will give an interrupt when it overflows.
I am finding that TIMER0 is actually better on these more modern chips ( better range of pre/post scalers).
If your crystal is not working the chip has a failsafe oscillator running at 1 MHz.
Well that's what I've found (your mileage may vary).

[Jim giordano]

Hi David,

Yes, I just want the whole thing to work at 32K. Seems simple enough.

The first thing I tried was #config rstosc=ext1x, fextosc=lp

It didn't make any difference.

Here is my actual full test program

#option Explicit
#chip 16F18313,.032768  ' 32K crystal on ra4-ra5
#config rstosc=ext1x, fextosc=lp
dir ra1 out ' led
' test clock by seeing how many instructions it can execute in a second
dim nn as word
ra1=1
do  ; flash led
for nn=1 to 3000:next  ; loop should take about 16 clock cycles / nn
ra1=0                  ; = 48000 ticks = change about every 1.5 seconds.
for nn=1 to 3000:next  ; testing shows led blinking too rapidly to
ra1=1                  ; tell, so running much faster than 32K
loop

[David Stephenson]

I think you have to set
DIR porta.4 IN
DIR porta.5 IN

[Jim giordano]

David-
I just tried that and it didn't make any difference.
Are you sure yours is actually running code at 32K?

edit:
Sorry David, I see now you explained this earlier. I must be getting senile in my old age.

[Jim giordano]

Okay, got it to work.

The problem is obvious from the .asm file produced. It says-

;OSCCON1 = 0x60 ' NOSC HFINTOSC; NDIV 1 - Common as this simply sets the HFINTOSC
    movlw   96
    banksel OSCCON1
    movwf   OSCCON1

despite my config line=

#config rstosc=ext1x, fextosc=lp

Unless there is some entry one can put in the config line to force the correct osccon that I haven't run across yet.

So I forced it after the startup by adding the code-

osccon1=b'01110000'
do while (!ORDY):loop

which made it run correctly.

NOTE: This is exactly what David said https://sourceforge.net/p/gcbasic/discussion/579126/thread/346d9e87a7/#4629 on 2019-10-19 !!!

and what Evan hinted at here https://sourceforge.net/p/gcbasic/discussion/579126/thread/346d9e87a7/#dba2

It just didn't sink in.

So, is there going to be some command for the config line to make this work properly without the extra clock switch?

[Anobium]

Excellent. I spotted the extra code last week. For the moment add your code. I need the compiler to expose whether the cpmpiler has selected the internal osc v external osc.

But, well done!