18F25J11 RTCC & remappable pin options

[Bruce]

I have received several emails asking for PBP code examples for using some of the newer 18F series with independent I/O mapping of onboard hardware peripherals, and for working with the new built-in RTCC hardware, so I'm posting a simple example here showing how to use the RTCC, and how to assign PWM to several pins.

These newer PICs that allow you to assign onboard peripherals like hardware PWM, USART, and a lot more, to different pins, are really nifty, and a lot like using the higher-end 24 series.

'****************************************************************
'*  Name    : TST_25J11_RTC.BAS                                 *
'*  Author  : B. Reynolds                                       *
'*  Notice  : Copyright (c) 2009 http://www.Rentron.com         *
'*          : All Rights Reserved                               *
'*  Date    : 1/25/2010                                         *
'*  Version : 1.0                                               *
'*  Notes   : Testing 18F25J11 RTCC & remappable pin options.   *
'*          :                                                   *
'****************************************************************

  ' NOTE: CONFIG options below are placed in the PBP 18F25J11.INC file with
  ' default config options commented out.

  ' CONFIG OSC=INTOSC, LPT1OSC=OFF, CP0=OFF, WDTEN=ON, XINST=OFF, IOL1WAY=OFF
  ' CONFIG STVREN=OFF, T1DIG=ON, FCMEN=OFF, WDTPS=512, RTCOSC=T1OSCREF

  ' Connect a 32.768 kHz watch crystal between pins 11 & 12 T1CKI & T1OSI
  ' with caps to match your crystal load capacitance.
  ' 11        12
  '  |---||---|
  '  |  xtal  |
  ' _|_      _|_
  ' ___      ___  2 x 12pF caps
  '  |        |
  ' gnd      gnd
   
  DEFINE DEBUG_REG PORTB
  DEFINE DEBUG_BIT 3      ' RB3 sends serial data to PC
  DEFINE DEBUG_BAUD 19200 ' 19200 bps
  DEFINE DEBUG_MODE 0     ' 1 = inverted, 0 = true

  DEFINE OSC 8
  
  X       VAR BYTE
  Hours   VAR BYTE
  Minutes VAR BYTE
  Seconds VAR BYTE
  Year    VAR BYTE
  Month   VAR BYTE
  Day     VAR BYTE
  Weekday VAR BYTE
  Duty    VAR WORD
  
  OSCCON = %01110000   ' using 8MHz internal osc
  
  ' // A/D disable & setup Timer1 for RTCC //
  ANCON0 = $ff
  ANCON1 = $1f         ' disable A/D on all analog pins
  T1CON = %10001001    ' external xtal, 1:1 prescale, no synch, 8-bit, timer1 on
  
  ' // PWM & port setup //
  Duty = 400           ' 50-50 PWM duty-cycle
  T2CON = %00000100    ' timer2 on, 1:1 prescale 
  PORTA = 0
  PORTB = 8            ' RB3 debug pin idles high
  PORTC = 0            ' PWM outputs low at POR 
  TRISA = 0
  TRISB = 0
  TRISC = 0
  CCP1CON = %00001100  ' setup for single-ended PWM output 
  PR2 = 199            ' setup for 10kHz 
  PSTR1CON = %00000001 ' P1A is driven by PWM
  CCP1CON.4 = Duty.0   ' load 10-bit duty cycle into
  CCP1CON.5 = Duty.1   ' duty registers
  CCPR1L = Duty >> 2
  
  ' // re-map PWM output to RA0, RC4 and RC3 pins //
  RPOR0 = 14        ' RA0, RP0 = P1A output
  RPOR15 = 14       ' RC4. RP15 = P1A output
  RPOR14 = 14       ' RC3, RP14 = P1A output
  
  ' // set initial time/date at POR // 
  GOSUB WRT_Enable  ' run unlock sequence to enable RTCC writes
  GOSUB LoadTime    ' setup RTCC time/date
  GOSUB WRT_Disable ' disable RTC writes after initial time & date setup

Main:
  RTCCFG = 3        ' set pointer to Year
  Year = RTCVALL    ' read Year
  RTCCFG = 2        ' set pointer to Month & Day
  Day = RTCVALL     ' read Day
  Month = RTCVALH   ' read Month & decrement pointer
  Hours = RTCVALL   ' read Hours
  Weekday = RTCVALH ' read Weekday & decrement pointer
  Seconds = RTCVALL ' read Seconds
  Minutes = RTCVALH ' read Minutes (pointer already at 0)
  PAUSE 990
  
' // date/time serial output format //
' Time: 03:33:00
' Monday: 
' Date: 01:25:2010
  
  ' // display Hours, Minutes, Seconds //
  DEBUG "Time: ",DEC (Hours>>4),DEC Hours & $0F,":", DEC (Minutes>>4),_
  DEC Minutes & $0F,":", DEC (Seconds>>4),DEC Seconds & $0F,13,10
  
  ' // display day of week //
  SELECT CASE Weekday
    CASE 0
      DEBUG "Sunday: ",13,10
    CASE 1 
      DEBUG "Monday: ",13,10
    CASE 2
      DEBUG "Tuesday: ",13,10
    CASE 3 
      DEBUG "Wednesday: ",13,10
    CASE 4
      DEBUG "Thursday: ",13,10
    CASE 5
      DEBUG "Friday: ",13,10
    CASE 6    
      DEBUG "Saturday: ",13,10
  END SELECT
   
  ' // display Month, Day, Year //
  DEBUG "Date: ",DEC2 Month & $1F,":", DEC (Day>>4), DEC Day & $0F,":",_
  "20",DEC (Year>>4), DEC Year & $0F,13,10,13,10,13,10

  GOTO Main

LoadTime:  ' // NOTE: time & date is in BCD format //
  RTCCFG = %00100011  ' set pointer to Year
  RTCVALL = %00010000 ' set Year to 2010
  RTCCFG = %00100010  ' set pointer to Month & Day
  RTCVALL = %00100101 ' set Day to the 25rd
  RTCVALH = 1         ' set Month to Jan (decrements pointer to Weekday & Hours)
  RTCVALL = %00000011 ' set Hour to 3
  RTCVALH = 1         ' 0=Sun, 6=Sat. set Weekday (decrements pointer to Minutes & Seconds)
  RTCVALL = 0         ' set Seconds to 0
  RTCVALH = %00110011 ' set Minutes to 33
  RTCCFG.7 = 1        ' RTCC enabled
  RETURN

WRT_Enable:           ' enable writes to RTCC registers
  EECON2 = $55        ' unlock sequence
  EECON2 = $AA        ' 
  RTCCFG.5 = 1        ' write enable RTCC register
  RETURN
  
WRT_Disable:          ' disable writes to RTCC registers
  EECON2 = $55
  EECON2 = $AA
  RTCCFG.5 = 0
  RETURN
      
  END

This shows how to re-map PWM output to RA0, RC4 and RC3 pins, and use the built-in
RTCC clock functions. These PICs are definitely worth looking at, so have fun...;o)

It does take a bit of time to learn how to use these guys, but it's very cool. You can re-
map almost every onboard hardware peripheral to work on any pin.

[rmteo]

Yes, these newer PIC18's are really nice and they do give you a small hint as to the power and flexibility of the 24-bit core devices. Pity, they do not get more interest here.

[Bruce]

I'm waiting on a few 24 samples. Figured I would give them a whirl.

[rmteo]

I started using PIC24/dsPIC33 (in particular the PIC24F's for their rich peripheral set) 2 years ago and am really pleased with their power and flexibility - they are pretty much all I use these days. I have used PIC18's occasionally due to the excellent Swordfish compiler which isn't available yet for the 24-bit core devices. They only time I used a PIC16 in the last 2 years was when the app called for a small physical package and settled on an 8-pin MSOP.

[Bruce]

Which compiler are you using for the PIC24F's ?

[rmteo]

If you wan't to stay with BASIC (like me), I believe your only option for now is mikroBASIC Pro for dsPIC. Otherwise, there is the free C30 compiler from MicroCHIP. Also, Dave Barker says that he is working on a 24-bit version of Swordfish.