There are 16 reserved I2C addresses. The following table shows the purposes of these addresses:
| I2C slave address | Direction bit (R/W) | Description |
0000 000 | 0 | General call address |
0000 000 | 1 | START byte |
0000 001 | X | CBUS address |
0000 010 | X | Reserved for different bus format |
0000 011 | X | Reserved for future purposes |
0000 1XX | X | Hs-mode master code |
1111 1XX | 1 | Device ID |
1111 0XX | X | 10-bit slave addressing |
The general call address is for addressing all devices connected to the I2C bus. If a device does not need the provided data, it can ignore this address (it does not issue the acknowledgement). If a device requires data from a general call address, it acknowledges this address and behaves as a slave-receiver. If one or more slaves acknowledge the general call address, the master does not know how many devices did it and does not see not-acknowledged slaves.
If you use a DLN-series adapter as I2C slave, you can configure it to support general call addressing or to ignore it.