Rtcc

[Bruce]

This was tested on a PIC18F25J11 running at 3V, but should work on your 46J11. Note it was tested with PBP3, but can easily be modified to work with earlier versions.

  #CONFIG
   CONFIG OSC = INTOSC 
   CONFIG LPT1OSC = OFF 
   CONFIG CP0 = OFF 
   CONFIG WDTEN = OFF 
   CONFIG XINST = OFF
   CONFIG IOL1WAY = OFF
   CONFIG STVREN = OFF 
   CONFIG T1DIG = OFF 
   CONFIG FCMEN = OFF 
   CONFIG WDTPS = 512 
   CONFIG RTCOSC = T1OSCREF
  #ENDCONFIG 

  ' Connect a 32.768 kHz watch crystal between pins 11 & 12 T1CKI & T1OSI
  ' with caps to match your crystal capacitance.
  ' 11        12
  '  |---||---|
  '  |  xtal  |
  ' _|_      _|_
  ' ___      ___  2 x 12pF caps
  '  |        |
  ' gnd      gnd
   
  DEFINE OSC 4 
  OSCCON = %01100000  ' using 4MHz internal osc
  
  ' // disable A/D & setup Timer1 for RTCC //
  ANCON0 = $ff
  ANCON1 = $1f        ' disable A/D on all analog pins 
  T1CON = %10001101   ' ext 32.768 kHz xtal, 1:1 prescale, no synch, 8-bit, timer1 on 
  TRISB.1 = 0         ' clear TRISB.1 for RTCC 1Hz output  
  PADCFG1 = %00000010 ' RTCC seconds clock is selected for output on the RTCC pin
  RTCCFG.2 = 1        ' set RTCC output enable bit
   
  EECON2 = $55        ' unlock sequence to enable writes to RTCC registers
  EECON2 = $AA
  RTCCFG.5 = 1        ' set bit 5 for RTCC write enable   
  RTCCFG.7 = 1        ' set bit 7 for RTCC clock enable 
  
  EECON2 = $55        ' lock sequence to disable writes to RTCC registers
  EECON2 = $AA
  RTCCFG.5 = 0        ' clear bit 5 to lockup & disable RTCC writes

Here:
  GOTO Here
 
  END

It produces a very accurate 1Hz clock out on RB1.

This is a working test version of a serial clock & 3 x 10KHz PWM outputs with the same PIC CLOCK_25J11.txt

Hope this helps.

[Gerd]

Bruce

Thank you very much for your help. I had internet problems on my home computer
so could not receive your response over the weekend. I am using now my work computer.
I am going to try it out and I believe the onboard rtcc is the same on all 18F chips.
Thanks again and best regards

Gerd