1996 Jun 27 27
Philips Semiconductors Product specification
8-bit microcontroller with on-chip CAN P8xC592
12 SERIAL I/O PORT: SIO0 (UART)
The Serial Port SIO0 is a full duplex (UART) serial I/O port
i.e. it can transmit and receive simultaneously. This Serial
Port is also receive-buffered. It can commence reception
of a second byte before the previously received byte has
been read from the receive register. However, if the first
byte has still not been read by the time reception of the
second byte is complete, one of these (first or second)
bytes will be lost. The SIO0 receive and transmit registers
are both accessed via the S0BUF SFR. Writing to S0BUF
loads the transmit register, and reading S0BUF accesses
to a physically separate receive register. SIO0 can operate
in 4 modes:
Mode 0 Serial data is transmitted and received through
RXD. TXD outputs the shift clock. 8 data bits are
transmitted/received (LSB first). The baud rate is
fixed at
1
⁄
12
of the oscillator frequency.
Mode 1 10 bits are transmitted via TXD or received
through RXD: a start bit (0), 8 data bits (LSB first),
and a stop bit (1). On receive, the stop bit is put
into RB8 of the S0CON SFR. The baud rate is
variable.
Mode 2 11 bits are transmitted through TXD or received
through RXD: a start bit (0), 8 data bits (LSB first),
a programmable 9
th
data bit, and a stop bit (1).
On transmit, the 9
th
data bit (TB8 in S0CON) can
be assigned the value of 0 or 1. With nominal
software, TB8 can be the parity bit (P in PSW).
During a receive, the 9
th
data bit is stored in RB8
(S0CON), and the stop bit is ignored. The baud
rate is programmable to either
1
⁄
32
or
1
⁄
64
of the
oscillator frequency.
Mode 3 11 bits are transmitted through TXD or received
through RXD: a start bit (0), 8 data bits (LSB first),
a programmable 9
th
data bit, and a stop bit (1).
Mode 3 is the same as Mode 2 except for the
baud rate which is variable in Mode 3.
In all four modes, transmission is initiated by any
instruction that writes to the S0BUF SFR.
Reception is initiated in Mode 0 when RI = 0 and REN = 1.
In the other three modes, reception is initiated by the
incoming start bit provided that REN = 1.
Modes 2 and 3 are provided for multiprocessor
communications. In these modes, 9 data bits are received
with the 9
th
bit written to RB8 (S0CON). The 9
th
bit is
followed by the stop bit. The port can be programmed so
that with receiving the stop bit, the Serial Port interrupt will
be activated if, and only if RB8 = 1.
This feature is enabled by setting bit SM2 in S0CON. This
feature may be used in multiprocessor systems.
For more information about how to use the UART in
combination with the registers S0CON, PCON, IE, SBUF
and the Timer register, refer to the 8051-based
“8-bit Microcontrollers Data Handbook IC20”
.
13 SERIAL I/O PORT: SIO1 (CAN)
SIO1 (CAN) provides the CAN (Controller Area Network)
serial-bus data communication interface. SIO1 (CAN)
replaces the SIO1 (I
2
C) serial interface as provided in the
microcontroller derivative P8xC552.
13.1 On-chip CAN-controller
CAN is the definition of a high performance
communication protocol for serial data communication.
The P8xC592 on-chip CAN-controller is a full
implementation of the CAN 2.0A protocol. With the
P8xC592 powerful local networks can be built, both for
automotive and general industrial environments. This
results in a much reduced wiring harness and enhanced
diagnostic and supervisory capabilities.
13.2 CAN Features
• Multi-master architecture
• Bus access priority determined by the message
identifier
• 2032 message identifier (2
11
standard frame CAN 2.0A)
• Guaranteed latency time for high priority messages
• Powerful error handling capability
• Data length from 0 up to 8 bytes
• Multicast and broadcast message facility
• Non destructive bit-wise arbitration
• Non-return-to-zero (NRZ) coding/decoding with
bit-stuffing
• Programmable transfer rate (up to 1 Mbit/s)
• Programmable output driver configuration
• Suitable for use in a wide range of networks including
the SAE's network classes A, B and C
• DMA providing high-speed on-chip data exchange
• Bus failure management facility
•
1
⁄
2
AV
DD
reference voltage.
