參數(shù)資料
型號(hào): TS87C51RD2-MIMD
元件分類: 8位微控制器
英文描述: 8-BIT MICROCONTROLLER
中文描述: 8位微控制器
文件頁(yè)數(shù): 30/74頁(yè)
文件大?。?/td> 689K
代理商: TS87C51RD2-MIMD
36
Rev. C - 06 March, 2001
TS80C51RA2/RD2
TS83C51RB2/RC2/RD2
TS87C51RB2/RC2/RD2
6.6.3. Given Address
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:
SADDR
0101 0110b
SADEN
1111 1100b
Given
0101 01XXb
The following is an example of how to use given addresses to address different slaves:
Slave A:
SADDR
1111 0001b
SADEN
1111 1010b
Given
1111 0X0Xb
Slave B:
SADDR
1111 0011b
SADEN
1111 1001b
Given
1111 0XX1b
Slave C:
SADDR
1111 0010b
SADEN
1111 1101b
Given
1111 00X1b
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 1; for slaves B and C, bit 1 is a don’t care bit. To communicate with slaves B and C, but
not slave A, 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
).
6.6.4. Broadcast Address
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.:
SADDR
0101 0110b
SADEN
1111 1100b
Broadcast =SADDR OR SADEN
1111 111Xb
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:
Slave A:
SADDR
1111 0001b
SADEN
1111 1010b
Broadcast
1111 1X11b,
Slave B:
SADDR
1111 0011b
SADEN
1111 1001b
Broadcast
1111 1X11B,
Slave C:
SADDR=
1111 0010b
SADEN
1111 1101b
Broadcast
1111 1111b
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 an address FFh. To communicate with slaves A and B, but not slave C, the master can send
and address FBh.
相關(guān)PDF資料
PDF描述
TS87C51RD2-VCAD 8-BIT MICROCONTROLLER
TS87C51RD2-VCBB 8-BIT MICROCONTROLLER
TS87C51RD2-VCBD 8-BIT MICROCONTROLLER
TS87C51RD2-VCBR 8-BIT MICROCONTROLLER
TS87C51RD2-VCEB 8-BIT MICROCONTROLLER
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