AT83C51SND1C_03 ATMEL [ATMEL Corporation], AT83C51SND1C_03 Datasheet - Page 141

• Manufacturer Part Number: AT83C51SND1C_03
• Description: Single-Chip Flash Microcontroller with MP3 Decoder and Human Interface
• Manufacturer: ATMEL [ATMEL Corporation]

Broadcast Address
Reset Address
4109E–8051–06/03
The following is an example of how to use given addresses to address different slaves:
The SADEN Byte is selected so that each slave may be addressed separately.
For slave A, bit 0 (the LSB) is a don’t-care bit; for slaves B and C, bit 0 is a 1. To com-
municate with slave A only, the master must send an address where bit 0 is clear (e.g.
1111 0000B).
For slave A, bit 1 is a 0; for slaves B and C, bit 1 is a don’t care bit. To communicate with
slaves A and B, but not slave C, the master must send an address with bits 0 and 1 both
set (e.g. 1111 0011B).
To communicate with slaves A, B and C, the master must send an address with bit 0 set,
bit 1 clear, and bit 2 clear (e.g. 1111 0001B).
A broadcast address is formed from the logical OR of the SADDR and SADEN registers
with zeros defined as don’t-care bits, e.g.:
The use of don’t-care bits provides flexibility in defining the broadcast address, however
in most applications, a broadcast address is FFh.
The following is an example of using broadcast addresses:
For slaves A and B, bit 2 is a don’t care bit; for slave C, bit 2 is set. To communicate with
all of the slaves, the master must send the address FFh.
To communicate with slaves A and B, but not slave C, the master must send the
address FBh.
On reset, the SADDR and SADEN registers are initialized to 00h, i.e. the given and
broadcast addresses are XXXX XXXXb (all don’t care bits). This ensures that the Serial
Port is backwards compatible with the 80C51 microcontrollers that do not support auto-
matic address recognition.
Slave A:SADDR = 1111 0001b
Slave B:SADDR = 1111 0011b
Slave C:SADDR = 1111 0010b
Slave A:SADDR = 1111 0001b
Slave B:SADDR = 1111 0011b
Slave C:SADDR = 1111 0010b
SADEN = 1111 1010b
Given = 1111 0X0Xb
SADEN = 1111 1001b
Given = 1111 0XX1b
SADEN = 1111 1101b
Given = 1111 00X1b
SADDR = 0101 0110b
SADEN = 1111 1100b
(SADDR | SADEN)=1111 111Xb
SADEN = 1111 1010b
Given = 1111 1X11b,
SADEN = 1111 1001b
Given = 1111 1X11b,
SADEN = 1111 1101b
Given = 1111 1111b,
AT8xC51SND1C
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