Quote Originally Posted by CBUK
ah ha, ive sorted a sloution that seems to be working very well, posted below:

symbol but =portc.6
owrite but,1,[$33h]
delayms 20
oread but,0,[ {values of serial numbers} ]

' the $33h is the address for the button to spew its serial number. there are other commands that you shoud reference to the data sheet for the required memory read/ write/ scratchpad... etc

i have developed the iButtons to form part of a security access scheme with a master key that allows the user to add, delete or change level access for various pin outs on the pic.

if anybody has a spare few hours id strongly recomend you look at the power if these devices! and even the general application of 1-wire communication!

chris
Hi Chris,

I'm very interested in your project, becurse I also tries to do an Access Control system with DS1990A. Have no problem to communicate with the iButton, but wants to connect a RTC for logging date (YYMMDDHHMM) in EEPROM (24LC65). One of my problem is that I store the iButton in a simular EEPROM, and if it is to many (over 50) it takes to long time to react on the iButtons in EEPROM. How can I find away to quick check if an iButton is authorized (stored in EEPROM).

Greatful for help

Bosse