7.3.3.2.1.1 Address Initialize

The address-initialize command initializes the addresses of the devices in the daisy chain. This command must be performed one time because the addresses are stored in the devices EEPROM and loaded on every reset event.

After the address-initialize command phase, the host provides one word of address-assign, command-byte data, as shown in Figure 23. This word contains the desired address of the first device on the daisy chain in the A4:A0 field. Although any value from 0 to 31 is allowed for this field, it is recommended to keep first device address at 01h. The last device address must never exceed 31. After the address-assign command bytes have been transmitted by the host, the daisy chain goes through a sequence of position detection and self-programming events where the devices in the chain identify their respective locations on the bus. During this process, the host receives incremental address response data from the individual TMP107 devices in the daisy chain that indicate the point in the chain up to which the address assignment has been completed. These responses arrive at intervals of 7 ms. This procedure is represented in Figure 23.

Figure 23. Address-Initialize Command

Until the initialization process is completed, daisy-chain communication is directed toward the host. Do not send any new commands to the chain during this period. If the address initialization sequence is interrupted as a result of glitches or disconnects in the daisy chain, the devices stall communication. In the event of a stall, each device has an internal timeout of one second (only for the address-initialize command). After one second, the communication interface in the TMP107 device resets, and the host regains control of the chain. Float the I/O2 pin of the last device in the chain. The address initialization procedure occurs serially from one device to the next; therefore, the maximum current consumed by the chain must not exceed the current required to initialize one device.