real time clock

[sayzer]

....
for am 12 hr mode
writehour = 00100011 = $C4
readhour = 10100011 = $A3

for pm 12 hr mode
readhour = 10101011 = $AB
writehour = 00101011 = $D4

hi jessey,

When reading or writing you change the register address command.

Reading: $85
Writing : $84

If you want to "Write Hour" to the chip, then you first send $84 command and prepare the chip to accept the incoming data for "hour". Then right after that you send your byte variable consisting your "hour data".

If sending 12Hr AM mode then the Bit7 of your byte should be "0" indicating 12Hr mode, and Bit5 should be "1 " indicating "AM".

Sending $85 command to the chip will be for "read hour" command and incoming data byte will consist of "hour data". Thus for reading, you do not set a byte to write to the chip; just read the incoming data.

In this case, I need to correct your arrangement as below.

12AM hr mode
writehour = 00100011
Bit7=0 12hr mode.
Bit5=1 AM mode.
Correct

readhour = 10100011
No need.
Just send $85 and read the incoming data.


12PM hr mode
writehour = 00101011
Bit7=0 12hr mode.
bit5=1 AM mode.
incorrect

The correct byte arrangement:
writehour = 00001011
Bit7=0 12Hr mode.
bit5=0 PM mode.


readhour = 10101011
No need.
Just send $85 and read the incoming data.

I have another question for you if you understand Melanie's ConvertBCD: subroutine above, what does the DIG 1 & DIG 0 do?

In a byte or word, the digits counts from right to left (just like Arabic).

Say we have a byte and it is set to Decimal 245.

ex:
Test VAR BYTE
Apple VAR BYTE

Test = 245

In this case, from right to left,
Test Dig 0 is 5
Test Dig 1 is 4
Test Dig 2 is 2

to extract any of these numbers and use in somewhere else, we use;

Apple = Test Dig 1

Apple is now 4.



How is it now ?
---------------------

[jessey]

Hi sayzer,

I can't seem to figure out what I'm doing wrong here. This is what I did to change to the 12 hour am & pm mode. I got rid of the "writehour CON $84" statement, as its not required anymore. Then I created these four con's and variable below:

Mode VAR BIT
Mode = 0   ' starts in am mode on initial power-up
writehour_am    con $C4
writehour_pm    con $D0
am CON 0
pm CON 1

Then in your setup: subroutine I added this code block to replace your code block for the hourx:

        IF Mode = am THEN
          reg_adr = writehour_am   ' = 00100011
        ELSE
          reg_adr = writehour_pm   ' = 00001011
        ENDIF
        outbyte = hourx
        gosub w_out

Then in your in your sethour: subroutine I added this code block to replace yours for setting the hour:

        IF CHNG = 0 THEN        'change the hour on display
            pause 100
            hour = hour + 1
            IF hour > 12 THEN
              IF Mode = am THEN
                 Mode = pm
              ELSE
                 Mode = am
              ENDIF
                 hour = 1
            ENDIF
          call send
        ENDIF

And that's it. Seems simple enough but it won't work. After I finish setting the clock and return to the start: subroutine it shows two zero's instead of what I set it to. I added these modifications to your original code without my added timer counter routines to rule out any of the other changes I made to your code. I used a converter that is here: http://www.itlocation.com/en/softwar...,download,.htm to calculate the HEX values. Its a great converter because it allows copping and pasting the values into and out of the converter.

I found a discrepancy in the manual for what you said about bit 7.

You said:

If sending 12Hr AM mode then the Bit7 of your byte should be 
"0" indicating 12Hr mode, and Bit5 should be "1 "
indicating "AM".

And the manual says:

                        AM-PM/12-24 MODE 
Bit 7 of the hours register is defined as the 12- or 24-hour 
mode select bit. When high, the 12-hour mode is selected.
In the 12-hour mode, bit 5 is the AM/PM bit with logic high 
being PM.

I changed the bits to what the manual says but still ended up with the same results. I'll keep plugging away at it to see if I can figure it out but in the meantime would you have any ideas on what I've done wrong here?

Thanks
jessey

[sayzer]

IF hour > 12 THEN

     IF Mode = am THEN
                Mode = pm
     ELSE
                Mode = am
     ENDIF
     
     hour = 1

ENDIF

Why don't you try this:

IF hour > 12 THEN
     TOGGLE Mode
     hour = 1
ENDIF

For the Bit7 and Bit5, I checked again, you are right. I apologize.

Say your Bit7 and Bit5 are set correctly.
The rest, Bit4,Bit3,Bit2,Bit1 and Bit0 are consisting your hour data (in AM mode). In PM mode, Bit5 is also consisting hour data.
You are setting the hour data the same each time.

[shahidali55]

Is it possible to use a 32.768 Khz crystal with picbasic pro ?
I know the minimum given in manual is 4 Mhz, but is there anyway to use a 32.768 Khz to reduce power consumption ? ? ?

[skimask]

Is it possible to use a 32.768 Khz crystal with picbasic pro ?
I know the minimum given in manual is 4 Mhz, but is there anyway to use a 32.768 Khz to reduce power consumption ? ? ?

If you run a PIC at 32.768khz, with a PBP program that's compiled to run at 4Mhz, the only thing that'll happen is it'll run 122 times slower (i.e. pause 1 @ 4Mhz = pause 122 @ 32.768khz).

[paul borgmeier]

I know the minimum given in manual is 4 Mhz

Not that helps here, but 3 MHz also is an option as is given in the manual

Define OSC 3

[shahidali55]

I've already tried that skimask. . .
It really puts all the PBP routines off . . .
LCDOUT takes like 3 seconds to print 16 digits . .

[skimask]

It really puts all the PBP routines off . . .
LCDOUT takes like 3 seconds to print 16 digits . .

Which is exactly what I'd expect...unless you write the code in assembly, PBP will time everything like it was running 4Mhz. Maybe try 'lcd_commandus' and lcd_dataus' both set to 1 and see if it works like that at 32khz.

Which PIC are you using this time?
There is a clock switching feature in most newer PICs these days, can switch between the main (4Mhz or whatever) and the internal 32/37/40khz (depends on the datasheet you're looking at) 'backup' oscillator if configured correctly. I use it all the time to save power.