problems with I2C.... and ideas why dosent work?

[snood]

i got the datasheet here: http://pdfserv.maxim-ic.com/en/ds/DS1307.pdf

under the "Slave Receiver Mode (Write Mode)" section of page 11

also on page 12 the data diagram shws a word address.

this is highly confusing.

Snood

edit: equaly it says: The DS1307 operates as a slave device on the I2C bus. Access is obtained by implementing a START
condition and providing a device identification code followed by a register address.

not "serial" but "i2c"

are you looking at an old version maybe?

[NavMicroSystems]

Hi Arch,

Snood has got more than one tested and working examples.

If one doesn't accept that 8 bits make a byte
and 16 bit make a word
and decimal 25 is different from hex 25
there is nothing we can do in addition.

[Archilochus]

Just down-loaded the sheet in your link, and it is different than the one I got from Maxim's site on March 19 of this year.

The "I2C" vs "serial" wording I think was just due to some patent / copyright issues.

Since the 1307's register map only goes to $3F, writing a WORD for the register address probably causes problems. Use a BYTE instead - works for me!

Arch

[snood]

thanks Arch

where did hex come into the equation ralph? the calender is written in BCD so what's wrong with using 25 in the variable as PBP will just convert it into 00011001 if i defined the data as $25 then yes... i would be trying to use hex which would of course give 100101 or 37 decimal. but i AM using decimal so thats no problem

who said that i was denying that 8bits = byte and 16bits = word? i didnt

please refrain from being so scathing and be polite like Arch

thankyou

Paul

[NavMicroSystems]

The RTC works in BCD Format.

If you want to set the date to the 25th. you would have to write $25 not a decimal 25 (which is $19)

If you write a decimal 25 for the 25th of a month you are in trouble:
at midnight the RTC will increment the decimal 25 ($19) to $20 (NOT $1A, because we are talking BCD!),
which results in decimal 32, which is an invalid date in your decimal coding!

If you want decimal numbers for easier editing/calculation you have got to convert them.

See the examples you have got.

[Warrier]

Hi Sood:

Just thought I might ask the obvious... your PIC is running at 4MHz or less, correct? DS1307 has the standard clock frequency and may not run above 4MHz.

Try making the I2C clock line bipolar by DEFINE I2C_SCLOUT 1.

You need to allow some time for the write to I2C completion - 10msec may be enough.

For initialization of a virgin DS1307 take a look at Ms. Neuman's discussion at http://www.picbasic.co.uk/forum/show...ght=non-eeprom

-warrier