First, you can scan the bus to see which addresses have devices which respond to an I2C command. The datasheets show what possible addresses a device can be configured to be located at. Also, blocks of addresses usually are used by certain types of chips (like 0x50-0x5F and 0x30-0x3F are usually eeproms, 0x2D is usually a system hardware monitoring chip, 0x69 is usually a clocking chip, etc.) To confirm the identity, we do some specific query (again as specified by the datasheet) which can be used as a test. For example, some chips have specific registers which will always contain some specific values to identify things like vendor, chip ID, and die rev. So, if you are looking for a specific device and want to see if it is at a particular address, you'll have to try to communicate with it as per the datasheet to see if it responds in a way that you would expect. Unfortunately, there is no clear cut way of knowing what a chip is before talking with it (unlike other bus protocols, like PCI). Does this help? Phil Ashwin Nayak wrote: >Hi, > What I would like to know is how you guys can tell at which address >which hardware is located. Like you guys say that the pll is at address >0x69 etc.How can I tell if the device that I am looking for is at a >particular address. > >Ashwin > > > > >
