AT87C52X2-3CSUV Atmel, AT87C52X2-3CSUV Datasheet - Page 19
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AT87C52X2-3CSUV
Manufacturer Part Number
AT87C52X2-3CSUV
Description
Microcontrollers (MCU) Microcontroller
Manufacturer
Atmel
Datasheet
1.AT87C52X2-3CSUV.pdf
(55 pages)
Specifications of AT87C52X2-3CSUV
Data Bus Width
8 bit
Program Memory Type
EPROM
Program Memory Size
8 KB
Data Ram Size
256 B
Interface Type
UART
Maximum Clock Frequency
30 MHz
Number Of Programmable I/os
32
Number Of Timers
3 bit
Operating Supply Voltage
5 V
Maximum Operating Temperature
+ 70 C
Mounting Style
Through Hole
Package / Case
PDIL-40
Minimum Operating Temperature
0 C
Lead Free Status / Rohs Status
No
Broadcast Address
Reset Addresses
4184I–8051–02/08
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).
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 an address FFh. To communicate with slaves A
and B, but not slave C, the master can send and 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 will reply to any address, and so, that it is backwards compatible with the 80C51
microcontrollers that do not support automatic address recognition.
Table 7. SADEN Register
SADEN - Slave Address Mask Register (B9h)
Reset Value = 0000 0000b
Not bit addressable
Table 8. SADDR Register
SADDR - Slave Address Register (A9h)
Reset Value = 0000 0000b
Not bit addressable
Slave A:SADDR1111 0001b
Slave B:SADDR1111 0011b
Slave C:SADDR=1111 0010b
7
7
Broadcast =SADDR OR SADEN1111 111Xb
SADDR 0101 0110b
SADEN 1111 1100b
SADEN1111 1010b
Broadcast1111 1X11b,
SADEN1111 1001b
Broadcast1111 1X11B,
SADEN1111 1101b
Broadcast1111 1111b
6
6
5
5
4
4
3
3
2
2
1
1
0
0
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