Real time clock ICs

[Eng4444]

Hi,

If you dont use a backup battery for the 1307 make sure that the un-used leg for the backup function is tied to ground. You can find this in the datasheet but if this is not done the chip will not work properly (sometimes it doesn't, other times it does but never when you want it to).

We are using the 1307 and it is doing fine.


TRIS? = %00000000 ' all pins to output just replace ? with port name

SDA var Port?.? 'define port for I2C communication replace ?.? with pin
SCL var Port?.?

Hours var Byte
Minutes var Byte
Seconds var Byte
RTC var Byte
I2C_Adr_B var byte


RTC = % 11010000 ' Device adress on I2C bus
I2C_Adr_B=0

I2CWRITE SDA,SCL,RTC,I2C_Adr_B,[128,0,0,0,0,0,0,128] 'Reset time to 0 and stopped, 12 hour setting

Start_RTC:
I2C_Adr_B=0
I2CWRITE SDA,SCL,RTC,I2C_Adr_B,[0,0,0,0,0,0,0,16] 'Start RTC if you put a resistor and LED between the "SEC" pin and 5V it should start flash 1/s
return

RTC_Read:
I2C_Adr_B=0
I2CREAD SDA,SCL,RTC,I2C_Adr_B,[seconds,minutes, hours] ' in bcd code
return

call each part with a GOSUB

Good luck and enjoy

__________________________________________________ _____________

i wouldl ike to thank you so much! but now i returned home and far from my Lab. I will try it tomorrow. is it suitable for PIC16F876A? and by the way, how to set the date and time to: "10:15:30 01-06-2006 "? can you tell me how and in which part of your program?

thank you again....

[BobK]

Hi Eng4444,

The simplest way is to set those values as the variables for hours, minutes, seconds, month, date, year and then write them into the RTC. Obviously the minutes setting should be a few minutes ahead of the actual start time to allow you time to program the PIC and then put it into your board and start the board up. That's what I do to start the clock on my boards.

BobK

[Jumper]

Hi,

Just to be really sure. Don't forget to put pullup resistors 4k7 between [SDA --> 5V] and [SCL --> 5V].

Another thing we have seen is that adding "DEFINE I2C_SCLOUT 1" (this makes the SCL line bipolar) can help if there is a lot of noice in your set up. This is not the solution for a bad design just a way to try to get the best possible chance to communicate with the 1307.

I am sure that as soon as you get the chip to respond your learning curve will go thru the roof.

[Eng4444]

I'll try all of this in 4 hours... i really hope it will work!!