TRIS setting for the DS1302

[Dennis]

@Steve ..apologies .. was actually asking Malc-c about valentines day :-)
@ Steve , regarding these lines :

high rst         ' Ready for transfer
Shiftout IO, SCLK, LSBFIRST, [$bf] ' Read all 8 RTC registers in burst mode     
Shiftin IO, SCLK, LSBPRE, [rtcsec, rtcmin, rtchr, rtcdate, rtcmonth, rtcday, rtcyear, rtccontrol]
low rst         ' Reset RTC

I understand these
LSBFIRST ' MODE 0 - Shift data out lowest bit first. Clock idles low.
LSBPRE ' MODE 0 - Shift data in lowest bit first,Read data before sending clock. Clock idles low.
But what is the [$bf] ?

@Malc-c --to err is human :-)

Kind regards

Dennis

[Byte_Butcher]

$bf is the register address for clock burst mode read I believe.

Do a search for $bf in the ds1302 data sheet.


steve

[Dennis]

Yes had just checked data sheet just after I posted !
$bf is for burst mode :-)

Thanks to all who replied .. this is making a whole lot more sense now :-)

Kind regards
Dennis

[Dennis]

@ Steve ...
Do you have a snippet for the write in burst mode so one can set the clock ?

Kind regards

Dennis

[Byte_Butcher]

Sure, this should do it:

settime:    ' Subroutine to write time to RTC
        RST = 1         ' Ready for transfer
        Shiftout IO, SCLK, LSBFIRST, [$8e, 0]  ' Enable write
        RST = 0         ' Reset RTC
        RST = 1         ' Ready for transfer
            ' Write all 8 RTC registers in burst mode
        Shiftout IO, SCLK, LSBFIRST, [$be, rtcsec, rtcmin, rtchr, rtcdate, rtcmonth, rtcday, rtcyear, 0]
        rst = 0        
        Return

steve

[Dennis]

@Steve

My code before you replied ...

setclk:
        high rst         ' Ready for transfer  RTC pin must go high
        Shiftout ds_data, ds_clk, LSBFIRST, [$bf] ' send burst mode control $bf to read all 8 RTC registers in burst mode     
        Shiftout ds_data, ds_clk, LSBFIRST, [rtcsec, rtcmin, rtchr, rtcdate, rtcmonth, rtcday, rtcyear, rtccontrol] send the data
        low rst         ' Reset RTC reset pin

As you can see I was totally off the mark with the $bf , $be setting !

Ok but I have read in a lot of posts regarding the DS1302 and BCD conversion ..does this still apply ?

Kind regards
Dennis

[Dennis]

Hi all

I have been battling for over a week now trying to get the DS1302 clock chip working.

I think I finally have the format and code sorted , only problem is that my clock never ticks :-( in other words the time never changes!

Please could somebody either take a look at my code or advise me what I should check next.
I'm sure it is really something small or silly that I have overlooked.

Kind regards

Dennis

'device 18F4520 
'DS1302  test
'
'

'Ocsillator selections here
        OSCCON = $70            'Int CLK 8MHz
        OSCTUNE.6 = 1           'PLL 4x
        ADCON1= %00001111       '$0F = disable A/D converter
        cmcon   =   7 
        INTCON2.7 = 0     'switch pull-ups ON
'END of oscillator selections
  'timer/oscillator defines 
        DEFINE OSC 32            '4x 8MHz
'END of timer/oscillator defines
'
'
'Port IO directions and presets for port pins begin here
'TRISX = %76543210   << tris bit order numbering
'TRISA = %11111111       'All pins are outputs
'// Define port pins as inputs and outputs ...
        TRISA  = %00000000 'example only - TRISB = %00001111 ;Make B4-B7 outputs, B0-B3 inputs, 
        TRISB = %11111111  'for 4x4 keypad all input
        TRISC = %10000000
        TRISD = %00000000
        TRISE.0 = 0
        TRISE.1 = 0
        TRISE.2 = 0
'End of Port IO directions and presets for port pins begin here
'
'                   
'
'LCD defines begin here   
        DEFINE LCD_BITS 4 	'defines the number of data interface lines (4 or 8) 
        DEFINE LCD_DREG PORTD 	'defines the port where data lines are connected to
        DEFINE LCD_DBIT 4 	'defines the position of data lines for 4-bit interface (0 or 4)
        DEFINE LCD_RSREG PORTD 	'defines the port where RS line is connected to
        DEFINE LCD_RSBIT 2 	'defines the pin where RS line is connected to 
        DEFINE LCD_EREG PORTD 	'defines the port where E line is connected to 
        DEFINE LCD_EBIT 3 	'defines the pin where E line is connected 
        'DEFINE LCD_RWREG 0 	'defines the port where R/W line is connected to (set to 0 if not used)
        'DEFINE LCD_RWBIT 0 	'defines the pin where R/W line is connected to (set to 0 if not used)
        DEFINE LCD_COMMANDUS 2000 	'defines the delay after LCDOUT statement 
        DEFINE LCD_DATAUS 200 		'delay in micro seconds
'END of LCD DEFINES
'
'includes begin here
        INCLUDE "modedefs.bas"
       'end of includes
'
'HSER defines
        DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive
        DEFINE HSER_TXSTA 20h ' Enable transmit, BRGH = 0
        DEFINE HSER_SPBRG 207 ' 2400 Baud @ 32MHz, 0.17%
        DEFINE HSER_CLROERR 1 ' Clear overflow automatically
'HSER defines begin here

'-------------------------- Clock Variables ---------------------------------


'SCLK    var portC.3 ' DS1302 Clock Pin  7
'IO     var portC.4 ' DS1302 Data Pin   6
'rst     var portD.1 ' DS1302 Reset Pin 5


'pins
RST var PORTA.0 'DS1302 PIN 5
IO var PORTA.1 'DS1302 PIN 6
SCLK var PORTA.2  'DS1302 PIN 7

'variables
rtcyear var byte
rtcday var byte
rtcmonth var byte
rtcdate var byte
rtchr var byte
rtcmin var byte
rtcsec var byte
rtccontrol var byte


Main:
Low RST ' Reset DS1302 RTC
Low SCLK 'pull SCLK line LOW
' clock Set 16:45:00 04/14/08
rtcyear = $08
rtcday = $06
rtcmonth = $04
rtcdate = $14
rtchr = $16
rtcmin = $45
rtcsec = $00
Gosub SetTime   'fetch the time 
Goto loopy  'goto loopy

loopy:
Gosub gettime ' go fetch the time
Lcdout $fe, 1 'display date on top row on 16x2 lcd
lcdout hex2 rtcmonth, "/", hex2 rtcdate, "/" , hex2 rtcyear
lcdout $fe,$c0   'display time output on bottom line 16x2 lcd
lcdout hex2 rtchr, ":", hex2 rtcmin, ":", hex2 rtcsec
Pause 200 ' pause 0.2
Goto loopy  'return to main loop 




SetTime:  'this module sets the time using shiftout
RST = 1 ' bring the DS1302 RST line high and now ready for transfer

Shiftout IO, SCLK, LSBFIRST, [$8e, 0]   ' Enable write
RST = 0 ' Reset DS1302 RTC
RST = 1 ' bring reset line high and now ready for transfer
Shiftout IO, SCLK, LSBFIRST, [$be, rtcsec, rtcmin, rtchr, rtcdate, rtcmonth, rtcday, rtcyear, 0] ' Write all 8 RTC registers in burst mode
RST = 0 ' reset DS1302 RTC
Return 'return control to calling program


GetTime: ' Subroutine to read time from RTC
RST = 1 ' reset line high now ready for transfer
Shiftout IO, SCLK, LSBFIRST, [$bf] ' Read all 8 DS1302 RTC registers in burst mode using shiftout/shiftin
Shiftin IO, SCLK, LSBPRE, [rtcsec, rtcmin, rtchr, rtcdate, rtcmonth, rtcday, rtcyear, rtccontrol]
RST = 0 ' Reset RTC
Return  'return control to calling module

End

[Byte_Butcher]

Ok but I have read in a lot of posts regarding the DS1302 and BCD conversion ..does this still apply ?

If you use a push button to increment the minutes (or hours, etc) you will run into a problem because of the BCD.

This subroutine increments the minutes by 1 every time it's called.
It does the BCD to decimal conversion, increments the minutes, then converts the new number back to BCD before setting the time.

increminute:  'subroutine to do BCD to decimal conversion, increment and convert back to BCD
        mathtemp =(rtcmin>>4)*10+(rtcmin & $0F)  'convert BCD minutes into Decimal minutes        
        mathtemp=mathtemp+1   'increment by 1
        If mathtemp>59 then      'If minutes exceeds 59
              mathtemp=0            'reset to 0
              endif  
        rtcmin=((mathtemp DIG 1)<<4)+mathtemp DIG 0 'convert Decimal back to BCD
        rstcount = 0         
        gosub settime       
        return

steve