P89LV51RD2 Philips Semiconductors, P89LV51RD2 Datasheet - Page 41

• Manufacturer Part Number: P89LV51RD2
• Description: 8-bit 80C51 3 V low power 64 kB Flash microcontroller with 1 kB RAM
• Manufacturer: Philips Semiconductors

Philips Semiconductors
9397 750 14101
Product data
Fig 16. Schemes used by the UART to detect ‘given’ and ‘broadcast’ addresses when multiprocessor
communications is enabled
rx_byte(7)
rx_byte(0)
saden(7)
saden(0)
saddr(7)
saddr(0)
saddr(7)
saddr(0)
the SADDR to create the ‘Given’ address which the master will use for addressing
each of the slaves. Use of the Given address allows multiple slaves to be recognized
while excluding others.
This device uses the methods presented in
‘Broadcast’ address has been received or not.
The following examples will help to show the versatility of this scheme.
Table 28:
In the above example SADDR is the same and the SADEN data is used to
differentiate between the two slaves. Slave 0 requires a ‘0’ in bit 0 and it ignores bit 1.
Slave 1 requires a ‘0’ in bit 1 and bit 0 is ignored. A unique address for Slave 0 would
be 1100 0010 since slave 1 requires a ‘0’ in bit 1. A unique address for slave 1 would
be 1100 0001 since a ‘1’ in bit 0 will exclude slave 0. Both slaves can be selected at
the same time by an address which has bit 0 = 0 (for slave 0) and bit 1 = 0 (for
slave 1). Thus, both could be addressed with 1100 0000.
In a more complex system the following could be used to select slaves 1 and 2 while
excluding slave 0:
logic used by P89LV51RD2 UART to detect 'given address' in received data
Slave 0
Slave 1
logic used by P89LV51RD2 UART to detect 'given address' in received data
SADDR = 1100 0000
SADEN = 1111 1101
Given =
SADDR = 1100 0000
SADEN = 1111 1110
Given =
Slaves 0 and 1 scheme examples
rx_byte(7)
rx_byte(0)
saden(7)
saden(0)
.
.
.
.
.
.
Rev. 03 — 11 October 2004
1100 00X0
1100 000X
broadcast_address_match
given_address_match
Figure 16
8-bit microcontrollers with 80C51 core
002aaa527
to determine if a ‘Given’ or
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
P89LV51RD2
41 of 77