AT89C51SND1C-ROTUL Atmel, AT89C51SND1C-ROTUL Datasheet - Page 141

• Manufacturer Part Number: AT89C51SND1C-ROTUL
• Description: IC 8051 MCU FLASH 64K MP3 80TQFP
• Manufacturer: Atmel
• Series: 89Cr

Specifications of AT89C51SND1C-ROTUL

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, IDE/ATAPI, MMC, SPI, UART/USART, USB
• Peripherals: Audio, I²S, MP3, PCM, POR, WDT
• Number Of I /o: 44
• Program Memory Size: 64KB (64K x 8)
• Program Memory Type: FLASH
• Ram Size: 2.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.3 V
• Data Converters: A/D 2x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 80-TQFP, 80-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

18.6
18.6.1
4109L–8051–02/08
Automatic Address Recognition
Given Address
The automatic address recognition feature is enabled when the multiprocessor communication
feature is enabled (SM2 bit in SCON register is set).
Implemented in hardware, automatic address recognition enhances the multiprocessor commu-
nication feature by allowing the Serial Port to examine the address of each incoming command
frame. Only when the Serial Port recognizes its own address, the receiver sets RI bit in SCON
register to generate an interrupt. This ensures that the CPU is not interrupted by command
frames addressed to other devices.
If desired, the automatic address recognition feature in mode 1 may be enabled. In this configu-
ration, the stop bit takes the place of the ninth data bit. Bit RI is set only when the received
command frame address matches the device’s address and is terminated by a valid stop bit.
To support automatic address recognition, a device is identified by a given address and a broad-
cast address.
Note:
Each device has an individual address that is specified in SADDR register; the SADEN register
is a mask Byte that contains don’t care bits (defined by zeros) to form the device’s given
address. The don’t care bits provide the flexibility to address one or more slaves at a time. The
following example illustrates how a given address is formed.
To address a device by its individual address, the SADEN mask Byte must be 1111 1111b.
For example:
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 communicate
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).
Slave A:SADDR = 1111 0001b
Slave B:SADDR = 1111 0011b
Slave C:SADDR = 1111 0011b
SADDR = 0101 0110b
SADEN = 1111 1100b
Given = 0101 01XXb
SADEN = 1111 1010b
Given = 1111 0X0Xb
SADEN = 1111 1001b
Given = 1111 0XX1b
SADEN = 1111 1101b
Given = 1111 00X1b
The multiprocessor communication and automatic address recognition features cannot be
enabled in mode 0 (i.e, setting SM2 bit in SCON register in mode 0 has no effect).
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