Rainbow Electronics DS7505 - Manual (Page 10)

DS7505
Slave Address: Every slave device on the bus has a
unique 7-bit address that allows the master to access
that device. The DS7505’s 7-bit bus address is 1 0 0 1
A
2 A 1 A 0 , where A 2 , A 1 , and A 0 are user-selectable
through the corresponding input pins. The three
address pins allow up to eight DS7505s to be mul-
tidropped on the same bus.
Address Byte: The control byte is transmitted by the
master and consists of the 7-bit slave address plus a
read/write (R/W) bit (see Figure 7). If the master is
going to read data from the slave device then R/W = 1,
and if the master is going to write data to the slave
device then R/W = 0.
Pointer Byte: The pointer byte is used by the master to
tell the DS7505 which register is going to be accessed
during communication. The six MSBs of the pointer
byte (see Figure 8) are always 0 and the two LSBs cor-
respond to the desired register as shown in Figure 8.
Digital Thermometer and Thermostat
10 ______________________________________________________________________________________
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
1 0 0 1 A 2 A 1 A 0 R/ W
Figure 7. Address Byte
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0 0 0 0 0 0 P1 P0
Figure 8. Pointer Byte
START
CONDITION
SDA
SCL
STOP
CONDITION
ACK (OR NACK)
FROM RECEIVER
Figure 6. Start, Stop, and ACK Signals