RTC chip or PIC?

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  1. - 28th July 2009, 20:24 #1
    flotulopex's Avatar
    flotulopex
    flotulopex is offline Senior Member
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    Default Trigger the time (seconds) change

    Thanks mackrackit,

    My question was more about to understand how to trigger the time (seconds) change to start a display update or refresh.

    I was thinking about putting the PIC in low-power mode until the next second change happens; how to achieve this the best way?

    So is there any particular specification of RTC chips that will allow one to find a modell having, for example, a functionality setting a bit or a flag telling the second has changed?

    BTW, here is the code (multiple sources - thanks to All of them) I work on now for my tests:
    Code:
    <html><head></head><body><!--StartFragment--><pre><code><font color="#000080"><i>' PIC16F630 Fuses
</i></font><font color="#008000">@ DEVICE BOD_OFF
@ DEVICE CPD_OFF
@ DEVICE PROTECT_OFF
@ DEVICE MCLR_OFF
@ DEVICE PWRT_OFF
@ DEVICE WDT_OFF
@ DEVICE INTRC_OSC_NOCLKOUT

</font><font color="#000080"><i>'-------------------------------------------------------------------------------
' Registers   76543210
</i></font>WPUA       = %00110000 <font color="#000080"><i>'Weak Pull-up of PORTA for SCL and SDA on DS1307
</i></font>INTCON     = %00000000 <font color="#000080"><i>'Interrupts
</i></font>OSCCAL     = %01100000 <font color="#000080"><i>'Oscillator Calibration when Internal RC set to 4MHz
</i></font>OPTION_REG = %10000000 <font color="#000080"><i>'PORTA Pull-Ups/TMR0/Prescaler
</i></font>CMCON      = %00000111 <font color="#000080"><i>'Comparator Module is OFF
</i></font>TRISA      = %00000000 <font color="#000080"><i>'Set Input/Output
</i></font>PORTA      = %00000000 <font color="#000080"><i>'Ports High/Low
</i></font>TRISC      = %00000000 <font color="#000080"><i>'Set Input/Output
</i></font>PORTC      = %00000000 <font color="#000080"><i>'Ports High/Low

'-------------------------------------------------------------------------------
'PORTA.0 = ICSP Data
'PORTA.1 = ICSP Clock
'PORTA.2
'PORTA.3 = MCLR
'PORTA.4 = SDA
'PORTA.5 = SCL
'PORTC.0 = LCD-DB4
'PORTC.1 = LCD-DB5
'PORTC.2 = LCD-DB6
'PORTC.3 = LCD-DB7
'PORTC.4 = LCD-E
'PORTC.5 = LCD-RS

'-------------------------------------------------------------------------------
' LCD cabling
'-       ( 1) Vss - GND
'-	 ( 2) Vdd / Vcc +5V
'-	 ( 3) Vee / Vo / Contrast adjust / Pot 4k7(1-2-W3) or R2k2 (GND-3)
'PORTC.5 ( 4) RS
'-	 ( 5) R/W -&gt; to Vss
'PORTC.4 ( 6) E
'PORTC.0 (11) DB4
'PORTC.1 (12) DB5
'PORTC.2 (13) DB6
'PORTC.3 (14) DB7

</i></font><b>DEFINE </b>LCD_DREG PORTC   <font color="#000080"><i>'LCD data port 
</i></font><b>DEFINE </b>LCD_DBIT 0       <font color="#000080"><i>'LCD data starting PORT.bit (0 or 4)
</i></font><b>DEFINE </b>LCD_RSREG PORTC  <font color="#000080"><i>'LCD register select port 
</i></font><b>DEFINE </b>LCD_RSBIT 5      <font color="#000080"><i>'LCD register select bit 
</i></font><b>DEFINE </b>LCD_EREG PORTC   <font color="#000080"><i>'LCD enable port 
</i></font><b>DEFINE </b>LCD_EBIT 4       <font color="#000080"><i>'LCD enable bit 

'-------------------------------------------------------------------------------
' Variables
</i></font>SDA      <b>VAR </b>PORTA.4 <font color="#000080"><i>'DS1307 SDA pin #5
</i></font>SCL      <b>VAR </b>PORTA.5 <font color="#000080"><i>'DS1307 SCL pin #6
'SDOut    var PORTC.2
</i></font>DB       <b>VAR BYTE</b>[8] <font color="#000080"><i>'Data byte array
</i></font>RTCSec   <b>VAR </b>DB[0]   <font color="#000080"><i>'alias individual bytes in array
</i></font>RTCMin   <b>VAR </b>DB[1]
RTCHour  <b>VAR </b>DB[2]
RTCDay   <b>VAR </b>DB[3]
RTCDate  <b>VAR </b>DB[4]
RTCMonth <b>VAR </b>DB[5]
RTCYear  <b>VAR </b>DB[6]
RTCCtrl  <b>VAR </b>DB[7]
AMPM     <b>VAR BIT
</b>A_Ctr    <b>VAR BYTE    </b><font color="#000080"><i>'counter
</i></font>B_Ctr    <b>VAR BYTE    </b><font color="#000080"><i>'counter
</i></font>Day_T    <b>VAR BYTE
</b>Day      <b>VAR BYTE</b>[3]
Day[0] = 0
Day[1] = 0
Day[2] = 0

<font color="#000080"><i>'-------------------------------------------------------------------------------
</i></font><b>PAUSE </b>1000        <font color="#000080"><i>'time for LCD to settle
</i></font><b>LCDOUT </b>$FE, 1     <font color="#000080"><i>'Clear LCD
</i></font><b>GOSUB </b>WRITE_1307  <font color="#000080"><i>'set the time or don't

</i></font>MAIN:
   <b>GOSUB </b>READ_1307 <font color="#000080"><i>'Read the time &amp; date
   </i></font><b>GOSUB </b>LCD
   <b>PAUSE </b>1000
<b>GOTO </b>MAIN:

<font color="#000080"><i>'-------------------------------------------------------------------------------
</i></font>LCD:

<font color="#000080"><i>'Hour in &quot;hh:mm:ss&quot;
</i></font><b>LCDOUT </b>$FE, 2, <b>DEC </b>(RTCHour&gt;&gt;4 &amp; $0F), <b>DEC</b>(RTCHour &amp; $0F),<font color="#FF0000">&quot;:&quot;</font>, _
               <b>DEC</b>((RTCMin&gt;&gt;4)&amp; $0F), <b>DEC</b>(RTCMin &amp; $0F),<font color="#FF0000">&quot;:&quot;</font>, _
               <b>DEC</b>((RTCSec&gt;&gt;4)&amp; $0F), <b>DEC</b>(RTCSec &amp; $0F)
<font color="#000080"><i>'Day
</i></font>B_Ctr = 0
<b>FOR </b>A_Ctr = (((RTCDay &amp; $07)-1)*3) <b>TO </b>(((RTCDay &amp; $07)-1)*3)+2
  <b>LOOKUP </b>A_Ctr,[<font color="#FF0000">&quot;SunMonTueWedThuFriSat&quot;</font>],Day_T
  Day[B_Ctr] = Day_T
  B_Ctr = B_Ctr + 1
<b>NEXT </b>A_Ctr
<b>LCDOUT </b>$FE, 2, $FE, $C0, Day[0], Day[1], Day[2]

<font color="#000080"><i>'Date in &quot;mm-dd-yyyy&quot;
</i></font><b>LCDOUT </b>$FE, $C4, <b>DEC</b>((RTCDate&gt;&gt;4)&amp; $03), <b>DEC</b>(RTCDate &amp; $0F),<font color="#FF0000">&quot;-&quot;</font>, _
                 <b>DEC</b>((RTCMonth&gt;&gt;4)&amp; $01), <b>DEC</b>(RTCMonth &amp; $0F),<font color="#FF0000">&quot;-&quot;</font>, _
                 <b>DEC</b>(((RTCYear&gt;&gt;4)&amp; $0F)*100),<b>DEC</b>(RTCYear &amp; $0F)

<b>RETURN    
    
</b><font color="#000080"><i>'-------------------------------------------------------------------------------    
</i></font>READ_1307:
<font color="#000080"><i>' Read order is in Secs,Mins,Hours,Day,Date,Month,Year,Control
</i></font><b>I2CREAD </b>SDA,SCL,$D0,$00,[<b>STR </b>DB\8] <font color="#000080"><i>' Read string of 8 bytes from DS1307
</i></font><b>RETURN

</b><font color="#000080"><i>'-------------------------------------------------------------------------------
</i></font>WRITE_1307:
<font color="#000080"><i>'Set time &amp; date to 23:59:55, Day 2, Date:Month:Year 27:08:2009
</i></font><b>I2CWRITE </b>SDA,SCL,$D0,$00,[$55,$59,$23,$02,$27,$08,$29,$90] <font color="#000080"><i>' Write to DS1307

</i></font><b>RETURN                  </b><font color="#000080"><i>' Sec Min Hr  Day D   M   Y   Control

</i></font><b>END
</b></code></pre><!--EndFragment--></body>
</html>
    Roger
  2. - 28th July 2009, 20:29 #2
    dhouston's Avatar
    dhouston
    dhouston is offline Prolific Poster
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    Default

    Many output a square wave from (1Hz to 32kHz for the M41T81). You can monitor it. At 1Hz, a rising edge comes once per second.
    www.davehouston.net
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