********************************************************************
* Clock2 - Coco3FPGA Analog Board RTC Driver
* for the Maxim Integrated DS3231 RTC
* Coco3FPGA ONLY!
*
* $Id$
*
* Edt/Rev  YYYY/MM/DD  Modified by
* Comment
* ------------------------------------------------------------------
*   1      2004/08/18  Boisy G. Pitre
* Separated clock2 modules for source clarity.
*
*   2      2017/01/21  Robert Gault
* Modified clock2_elim.asm to work with the DS3231 on the Coco3FPGA
*
*   3      2017/01/23  Gary Becker
* Corrected the timing of the Read/Write activation routines
*
*   4      2017/01/23  Robert Gault
* Corrected a bug in the Setime routine and added a "stpreg" routine
*
*   5      2017/01/24  Bill Pierce
* Removed erronius "stpreg" routine, cleaned up code, re-assembled, IT WORKS!

         nam   Clock2    
         ttl   Coco3FPGA Analog Board RTC Driver

         ifp1            
         use   defsfile
         endc            

tylg     set   Sbrtn+Objct
atrv     set   ReEnt+rev
rev      set   $00
edition  set   4

* All bits not specified must be set to 0!
RTC.sec  equ   $00        0-59
RTC.min  equ   $01        0-59
RTC.hr   equ   $02        bit 6 12/24, bit5 PM/AM, or 20hr, bit4 10hr, bit3-0 hr:0-23
RTC.day  equ   $03        bit 2-0: 1-7
RTC.date equ   $04        bit5-4 10 date, bit 3-0 date: 1-31
RTC.mn   equ   $05        bit4 10 mn, bit3-0 mn
RTC.yr   equ   $06        bit7-4 10yr, bit3-0 yr
RTC.base equ   $FF80
RTC.data equ   $FF81      data I/O
RTC.cmd  equ   $FF82      $D1=read, $D0=write
RTC.adr  equ   $FF83      indicates 00h-06h see above
RTC.tog  equ   RTC.base   set 1 then 0
RTC.stat equ   RTC.base   wait for $80 to show ready

         mod   eom,name,tylg,atrv,JmpTable,RTC.base

name     fcs   "Clock2"
         fcb   edition

JmpTable                 
         lbra  INIT
         bra   GetTime
         nop
         lbra  SetTime
		 lbra  GetSta
		 lbra  SetSta
		 lbra  TERM

GetTime  ldx   M$Mem,pcr  get RTC base address from fake memory requirement
         ldd   #$D106     read and year
         sta   2,x
         bsr   rdreg
         lda   1,x        get year
         bsr   bcd2hex
         sta   <D.Year   
         ldb   #5         month register address
         bsr   rdreg
         lda   1,x
         anda  #%11111    keep only month
         bsr   bcd2hex       
         sta   <D.Month  
         ldb   #4         day of month register address
         bsr   rdreg
         lda   1,x
         bsr   bcd2hex       
         sta   <D.Day    
         ldb   #2         hour register address
         bsr   rdreg
         lda   1,x
         anda  #%111111   assume 24hr clock
         pshs  a
         anda  #%11111    limit to 19
         bsr   bcd2hex
         puls  b          recover original time
         andb  #%100000   test for 20+
         beq   no20
         adda  #20
no20     sta   <D.Hour   
         ldb   #1         minute register address
         bsr   rdreg
         lda   1,x
         bsr   bcd2hex
         sta   <D.Min    
         clrb             second register address
         bsr   rdreg
         lda   1,x
         bsr   bcd2hex
         sta   <D.Sec    
UpdTExit rts             

rdreg    stb   3,x        set mode
         ldb   #1         activate
         stb   ,x
LP1      lda   ,x         Done yet?
         bmi   LP1        No, loop
         clr   ,x         Clear for activation
LP2      lda   ,x         get status
         anda  #$80
         beq   LP2      Update In Progress, loop
         rts

* Convert Bitcode to Hex
bcd2hex  pshs  b
         tfr   a,b	copy the bcd number
         andb  #15	keep the lowest digit
         pshs  b        save it
         anda  #$F0
         ldb   #160
         mul            times 10
         adda  ,s+      add partials
         puls  b,pc

SetTime  pshs  cc         save interrupt status
         orcc  #IntMasks  disable IRQs
         ldx   M$Mem,pcr  get RTC base address from fake memory requirement
         ldd   #$D006     write and year
         sta   2,x
         ldy   #D.Time    point [Y] to time variables in DP
         lda   ,y+        get year
         bsr   hex2bcd
         sta   1,x
         bsr   rdreg
         lda   ,y+        month
         bsr   hex2bcd
         sta   1,x
         ldb   #5         month
         bsr   rdreg
         lda   ,y+        day
         bsr   hex2bcd
         sta   1,x
         ldb   #4         day
         bsr   rdreg
         lda   ,y+        hour
         bsr   hex2bcd
         sta   1,x
         ldb   #2         hour
         bsr   rdreg
         lda   ,y+        minute
         bsr   hex2bcd
         sta   1,x
         ldb   #1         minute
         bsr   rdreg
         lda   ,y         sec
         sta   1,x
         clrb             sec = 0
         bsr  rdreg
         puls  cc         Recover IRQ status
         rts

* Convert Hex to Bitcode
hex2bcd  pshs  b
         ldb   #$FF
lp10     incb
         suba  #10
         bcc   lp10
         adda  #10
         lslb
         lslb
         lslb
         lslb
         pshs  b
         adda  ,s+
         puls  b,pc

INIT     equ   *
GetSta   equ   *
SetSta   equ   *
TERM     equ   *
         rts

         emod            
eom      equ   *         
         end