XA-S3 Datasheet, PDF (30/52 Pages) NXP Semiconductors – XA 16-bit microcontroller 32 K/1 K OTP/ROM/ROMless, 8-channel 8-bit A/D, low voltage 2.7 V.5.5 V, I2C, 2 UARTs, 16 MB address range

Philips Semiconductors
XA 16-bit microcontroller
32 K/1 K OTP/ROM/ROMless, 8-channel 8-bit A/D, low voltage (2.7 V–5.5 V),
I²C, 2 UARTs, 16 MB address range
Preliminary specification
XA-S3
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 to 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 teated as
don’t-cares. In most cases, interpreting the don’t-cares as ones, the
broadcast address will be FF hexadecimal.
Upon reset SADDR and SADEN 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
UART drivers which do not make use of this feature.
SnCON Address: S0CON 420
S1CON 424
MSB
Bit Addressable
Reset Value: 00H
SM0 SM1 SM2 REN TB8 RB8
TI
Where SM0, SM1 specify the serial port mode, as follows:
SM0
0
0
1
1
SM1
0
1
0
1
Mode
0
1
2
3
Description
shift register
8-bit UART
9-bit UART
9-bit UART
Baud Rate
f_OSC/16
variable
f_OSC/32
variable
LSB
RI
BIT
SnCON.5
SnCON.4
SnCON.3
SnCON.2
SnCON.1
SnCON.0
SYMBOL
SM2
REN
TB8
RB8
TI
RI
FUNCTION
Enables the multiprocessor communication feature in Modes 2 and 3. In Mode 2 or 3, if SM2 is set to 1, then RI
will not be activated if the received 9th data bit (RB8) is 0. In Mode 1, if SM2=1 then RI will not be activated if a
valid stop bit was not received. In Mode 0, SM2 should be 0.
Enables serial reception. Set by software to enable reception. Clear by software to disable reception.
The 9th data bit that will be transmitted in Modes 2 and 3. Set or clear by software as desired. The TB8 bit is not
double buffered. See text for details.
In Modes 2 and 3, is the 9th data bit that was received. In Mode 1, if SM2=0, RB8 is the stop bit that was
received. In Mode 0, RB8 is not used.
Transmit interrupt flag. Set when another byte may be written to the UART transmitter. See text for details.
Must be cleared by software.
Receive interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or at the end of the stop bit time
in the other modes (except see SM2). Must be cleared by software.
SU00597C
Figure 21. Serial Port Control (SnCON) Register
2000 Dec 01
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