18F4520 and Timer1 troubles

curt2go · Joined: 21 Nov 2003 Posts: 200

i am having some trouble getting timer1 to work with a 32,768 crystal on it. I have done this with other pics with success. Is there something weird with the pic and Timer1? Let me know if you have any thoughts.. TTY

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Here's a test program for an 18F452 with the Timer1 oscillator running
with an external 32.768KHz crystal on pins C0 and C1.
http://www.ccsinfo.com/forum/viewtopic.php?t=25824&start=7

Do you have the capacitors connected to the external crystal ?
The data sheet recommends 27pf.

curt2go · Joined: 21 Nov 2003 Posts: 200

the crystal is a 6pf. I even tried 15pf. I have used this crystal on other designs with 6 and it works fine. It is very weird. I am using the intrc_io for my main clock. Let me know if you have any other thoughts . Thanx

ckielstra · Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands

You tried the program linked to by PCM Programmer?

What is your compiler version?

curt2go · Joined: 21 Nov 2003 Posts: 200

I am running the same program. 3.249..

drh · Posted: Thu Jun 05, 2008 8:02 am

In section 12 on page 129 of the data sheet, DS39631A, there is information on using timer 1 as the system clock.
_________________
David

curt2go · Joined: 21 Nov 2003 Posts: 200

i have tried everything.. New crystals . Caps up to 33pf. New processor. I tried the exact program that was posted. I can see the crystal oscillating at 32.768Khz on pin OSC2. But the timer 1 output no matter what is about 6 seconds.. Any ideas?

curt2go · Joined: 21 Nov 2003 Posts: 200

i am totally retarded.. I have the crystal on the wrong pins.. I had them on the oscillator pins the the timer1 pins.. AHHHHHHHHHHHHHHHHHHH. TTY

mskala · Joined: 06 Mar 2007 Posts: 100 Location: Massachusetts, USA

Unrelated to your real problem, but also 4520 is in the list of pics that have an errata for timer1 usage, so check that file on microchips web site.