I2C communication

NewBee

Hi,

I need to use a· for loop to update sequential addresses on a DS1307 by·using the loop counter to step through the addresses.· I'm getting intermitten results using the decimal loop counter for the HEX address especially when I index to address $08 (RAM).

Here's what I'm trying to do.

Set_Clock:
· FOR cntr = 0 TO·8
··· DecConvert· = (datearray(cntr) / 10 << 4) + (datearray(cntr) // 10) ' decimal to BCD
··· I2COUT SDA, DS1307, cntr, [noparse][[/noparse]DecConvert]···································· ' update clock registers
'··· PAUSE 100
· NEXT
· RETURN

' Do a block read from clock registers
Get_Clock:
· FOR cntr = 0 TO·8
··· I2CIN SDA, DS1307, cntr, [noparse][[/noparse]DecConvert]·········································' retrieve clock registers
··· datearray(cntr) = DecConvert.NIB1 * 10 + DecConvert.NIB0············· ' BCD to decimal
'··· PAUSE 100
· NEXT
If this code is ok then I'm very confused about my intermitten operation problem.

Thanks,

Bob

$WMc%

NewBee

Have you tried 0 to 9 ?This would give you an extra place for the decimal point. I'm "grasping at straws" here,But it might help.

·This would be in the DEC to BCD loop.

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·

NewBee

Thanks for your help, the code is fine, the problem was not understood.· Therefore the was all the more illusive.

Thanks,

Bob

Tracy Allen

What do you mean by, "intermittent operation" and, "especially when I index to address $08 (RAM)." What happens?

I don't see anything wrong with your code. The cntr variable is fine as a loop counter and as an address into the DS1307.

Is the chip set up with 5 volt power, the backup battery, and pullup resistors to Vdd on SDA and SCL?

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Tracy Allen
www.emesystems.com

Ron Czapala

The clock settings use 8 bytes 0 thru 7.

Byte 8 is the first byte of the 56 bytes of non-volatile RAM. Are doing something special with byte 8?

NewBee

Tracy,

Actually the clock system works fine.· The code you see initializes the registers 0-7 properly.· I'm trying to use register 8, first byte of SRAM as an indicator the user has already set the clock inorder to prevent reloading of default date & time parameters.· The problem is I·can never get out of register 8 what I put in to it.· It also appears register 8·clear at·power down.· I'm using the 28138 prof dev board with a 2p40.· I just received the environmment about a month·ago so I don't think its a hw prob.

NewBee

Hi,

Just a quick follow up to let everyone know I actually had problems in my clockset and clok get functions. Not with the device communication as indicated in this post.