| The I2C protocol knows about two kinds of device addresses: normal 7 bit | |
| addresses, and an extended set of 10 bit addresses. The sets of addresses | |
| do not intersect: the 7 bit address 0x10 is not the same as the 10 bit | |
| address 0x10 (though a single device could respond to both of them). You | |
| select a 10 bit address by adding an extra byte after the address | |
| byte: | |
| S Addr7 Rd/Wr .... | |
| becomes | |
| S 11110 Addr10 Rd/Wr | |
| S is the start bit, Rd/Wr the read/write bit, and if you count the number | |
| of bits, you will see the there are 8 after the S bit for 7 bit addresses, | |
| and 16 after the S bit for 10 bit addresses. | |
| WARNING! The current 10 bit address support is EXPERIMENTAL. There are | |
| several places in the code that will cause SEVERE PROBLEMS with 10 bit | |
| addresses, even though there is some basic handling and hooks. Also, | |
| almost no supported adapter handles the 10 bit addresses correctly. | |
| As soon as a real 10 bit address device is spotted 'in the wild', we | |
| can and will add proper support. Right now, 10 bit address devices | |
| are defined by the I2C protocol, but we have never seen a single device | |
| which supports them. |