Learning the RTC
artkennedy
Posts: 174
in Propeller 1
I am trying to find the handle on the RTC functions before firing up my new DS3231 and I have a couple of questions.
From Extend5v4.FTH:
--- STAMP@ returns a 32-bit millisecond time + day of month in top 5-bits
pub STAMP@ ( --- dhmsc ) time @ day 1+ C@ 27 << + ;
When I call STAMP@ it returns milliseconds but no DOM.
Example:
... .DT --> Mon, 31 Jan 2001 00:16:47 UTC ok
... STAMP@ . --> 1021375 ok
... that is the number of milliseconds in the time but nothing for the 31st day of the month.
What am I missing?
From Extend5v4.FTH:
--- STAMP@ returns a 32-bit millisecond time + day of month in top 5-bits
pub STAMP@ ( --- dhmsc ) time @ day 1+ C@ 27 << + ;
When I call STAMP@ it returns milliseconds but no DOM.
Example:
... .DT --> Mon, 31 Jan 2001 00:16:47 UTC ok
... STAMP@ . --> 1021375 ok
... that is the number of milliseconds in the time but nothing for the 31st day of the month.
What am I missing?
Comments
--- select and set RTC device
pub SETRTC ( $opt.addr -- ) W>B ' sec# C! ' rtc# C! ;
The parameter $opt.addr -> does that indicate that the $opt.addr is a string. If the designation were 'addr' I would take it to mean the I2C address of the RTC but I am confused. Furthermore the Tachyon Extend source specifies $D0 as the address for DS3231. Other sources say $68. If I knew how to make this word work I would just try both.
He'p!
Just 7 lines down in the code "DS3231 $D0 SETRTC
--- Version 0.4 FORGET daymo TABLE daymo 0 || 31 || 59 || 90 || 120 || 151 || 181 || 212 || 243 || 273 || 304 || 334 || 365 || : DOM1 ( mm -- dom1 ) --- dom1 - 1st day of month 1- daymo SWAP 2 * + W@ --- fetch first day of month ( base 0 ) ; : SYSDAY ( yymmdd -- sysday ) --- 20010101 subtracted from yymmdd, --- sysday = number of days since 20010101 (Jan 01, 2001) base 0. HMS -ROT --- ( yymmdd -- yy dd mm ) 3RD 4 MOD --- ( -- yy dd mm lyf ) lyf = 1 if leap year OVER DOM1 1- --- ( -- yy dd mm lyf Zdom ) dom1 - 1 = Zdom, Zeroth day of month ROT 2 > --- ( -- yy dd lyf Zdom ldf ) ldf = 1 if March or later ROT NOT --- ( -- yy dd Zdom ldf lyf ) AND NOT --- ( -- yy dd Zdom lda ) lda = leap day addition if any + + 1+ --- ( -- yy doy ) doy = day of year (base 0) with leap adjustment, 1+ restores Zdom offset SWAP 1- --- ( -- doy pyy ) pyy = prev years DUP 4 / --- ( -- doy pyy pld ) pld = how many prev leap days SWAP 365 * + + --- ( -- sysday ) # of prev regular days - sum, sysday (see above) ; : DOY1 ( yy --- doy1 ) --- yy = year, doy1 = first day thereof , totally confirmed. 1- DUP 4 / --- num of prev leap days, calculation is done with ordinal of previous year SWAP 365 * + --- add leap days --> sysday of first doy ; : YRDOY ( sysday -- yy doy ) --- true year and doy ( includes leap day ) DUP 365 / 1+ DUP DOY1 --- guess the year and check it out --- ( sysday 365 / returns the year before the target...therefore 1+ ) 3RD SWAP - --- sysday - doy1 DUP 0< IF --- IF negative result ( means year is +1 ) DROP --- drop result 1- DUP DOY1 --- decrement year and try again ROT SWAP - --- sysday - doy1 --> good this time ELSE --- ELSE ROT DROP --- drop sysday THEN --- THEN ; : DAYMO ( doy -- mm dd ) --- derive month and day of month from day of year daymo 22 + FROM -2 BY 12 --- search backward through daymo for 1dom equal to or less than doy FOR DUP I W@ => IF I LEAVE THEN --- found it! NEXT DUP daymo - 2/ 1+ --- extract mm from search address -ROT W@ - 1+ --- subtract doy of first day of month from target doy ; : DAY>DATE ( sysday -- yymmdd ) --- sysday to yymmdd YRDOY ( sysday -- yy doy ) OVER 4 MOD 0 > NOT ( -- yy doy lyf ) --- leap year? OVER 59 > ( -- yy doy lyf ldf ) --- after leap day if any? AND + ( -- yy doy ) --- combine flags and use result to increment doy or not DAYMO ( -- yy mm dd ) --- 4TH 59 = ( -- yy mm dd lyf ) --- 4TH 4 MOD NOT AND ( -- yy mm dd ldsf ) --- ldsf = ld substitution flag IF ( -- yy mm dd ) --- if ld sensed 2DROP 2 29 ( -- yy mm' dd' ) --- leap day substituted THEN ( -- ) --- then SWAP 100 * + ( -- yy mmdd ) --- compile yymmdd SWAP 10000 * + ( -- yymmdd ) ; : DOW ( sysday -- dow ) 1+ 7 MOD ; : DATE+ ( yymmdd n -- yymmdd + n ) SWAP SYSDAY + DAY>DATE ; : DDAYS ( yymmdd yymmdd' -- ddays ) --- subtract yymmdd' from yymmdd --> days between two dates SYSDAY SWAP SYSDAY SWAP - ;