Rainbow Electronics AT83C24NDS - Manual (Page 7)

7
4234F–SCR–10/05
AT83C24
Address Byte The first byte to send to the device is the address byte. The device controls if the hardware
address (A2/CK, A1/RST, A0/3V pins on reset) corresponds to the address given in the
address byte (A2, A1, A0 bits).
If the level is not stable on A2/CK pin (or A1/RST pin, or A0/3V pin) at reset, the user has to send
the commands to the possible address taken by the device.
If A2/CK to A0/3V are tied to the host microcontroller and their reset values are unknown, a gen-
eral call on the TWI bus allows to reset all the AT83C24 devices and set their address after
A2/CK to A0/3V are fixed.
Figure 2. Address Byte
Up to 8 devices can be connected on the same TWI bus. Each device is configured with a differ-
ent combination on A2/CK, A1/RST, A0/3V pins. The corresponding address byte values for
read/write operations are listed below.
Table 2. Address Byte Values
A2
(A2/CK pin)
A1
(A1/RST pin)
A0
(A0/3V pin)
Address Byte
for
Read
Command
Address Byte
for
Write
Command
0 0 0 0x41 0x40
0 0 1 0x43 0x42
0 1 0 0x45 0x44
0 1 1 0x47 0x46
1 0 0 0x49 0x48
1 0 1 0x4B 0x4A
1 1 0 0x4D 0x4C
1 1 1 0x4F 0x4E
b7 b6 b5 b4 b3 b2 b1 b0
0 0 1 0 A2 A1 A0 R/W
Slave Address on 7 Bits
1 for READ Command
0 for WRITE Command