83C576 Datasheet, PDF (22/46 Pages) NXP Semiconductors – 80C51 8-bit microcontroller family 8K/256 OTP/ROM, 6 channel 10-bit A/D, 4 comparators, failure detect circuitry, watchdog timer

Philips Semiconductors
80C51 8-bit microcontroller family
8K/256 OTP/ROM, 6 channel 10-bit A/D, 4 comparators,
failure detect circuitry, watchdog timer
Product specification
83C576/87C576
D0
D1
D2
D3
D4
D5
D6
D7
D8
START
BIT
DATA BYTE
ONLY IN STOP
MODE 2, 3 BIT
SET FE BIT IF STOP BIT IS 0 (FRAMING ERROR)
SM0 TO UART MODE CONTROL
SM0 / FE SM1
SM2
REN
TB8
RB8
TI
RI
SCON
(98H)
SMOD1 SMOD0
–
0 : SCON.7 = SM0
1 : SCON.7 = FE
POF
LVF
GF0
GF1
Figure 20. UART Framing Error Detection
IDL
PCON
(87H)
SU00044
Using the Automatic Address Recognition feature allows a master to
selectively communicate with one or more slaves by invoking the
Given slave address or addresses. All of the slaves may be
contacted by using the Broadcast address. Two special Function
Registers are used to define the slave’s address, SADDR, and the
address mask, SADEN. SADEN is used to define which bits in the
SADDR are to be used and which bits are “don’t care”. The SADEN
mask can be logically ANDed with 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. The following examples will help to show the
versatility of this scheme:
Slave 0
SADDR =
SADEN =
Given =
1100 0000
1111 1101
1100 00X0
Slave 1
SADDR =
SADEN =
Given =
1100 0000
1111 1110
1100 000X
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:
Slave 0
SADDR =
SADEN =
Given =
1100 0000
1111 1001
1100 0XX0
Slave 1
SADDR =
SADEN =
Given =
1110 0000
1111 1010
1110 0X0X
Slave 2
SADDR =
SADEN =
Given =
1110 0000
1111 1100
1110 00XX
In the above example the differentiation among the 3 slaves is in the
lower 3 address bits. Slave 0 requires that bit 0 = 0 and it can be
uniquely addressed by 1110 0110. Slave 1 requires that bit 1 = 0 and
it can be uniquely addressed by 1110 and 0101. Slave 2 requires
that bit 2 = 0 and its unique address is 1110 0011. To select Slaves 0
and 1 and exclude Slave 2 use address 1110 0100, since it is
necessary t make bit 2 = 1 to exclude slave 2.
The Broadcast Address for each slave is created by taking the
logical OR of SADDR and SADEN. Zeros in this result are treated
as don’t-cares. In most cases, interpreting the don’t-cares as ones,
the broadcast address will be FF hexadecimal.
Upon reset SADDR (SFR address 0A9H) and SADEN (SFR
address 0B9H) are loaded with 0s. This produces a given address
of all “don’t cares” as well as a Broadcast address of all “don’t
cares”. this effectively disables the Automatic Addressing mode and
allows the microcontroller to use standard 80C51 type UART drivers
which do not make use of this feature.
Analog Comparators
Four analog comparators are provided on chip. Three comparators
have a common negative reference CMPR- and independent
positive inputs CMP1+, CMP2+, CMP3+ on port 3. The fourth
comparator has independent positive and negative inputs CMP0+
and CMP0- on port 2. The CMP register contains an output and
enable bit for each comparator. Figure 22 shows the connection of
the comparators.
When the comparator is enabled, the port should be configured by
the user as high impedance.
1998 Jun 04
22