p87c591vfb NXP Semiconductors, p87c591vfb Datasheet - Page 63

• Manufacturer Part Number: p87c591vfb
• Description: Single-chip 8-bit Microcontroller With Can Controller
• Manufacturer: NXP Semiconductors

Philips Semiconductors
14.3.4
The baud rate in Mode 0 is fixed to:
14.3.5
The baud rate in Mode 2 depends on the value of bit
SMOD1 in Special Function Register PCON. If SMOD1 =
0 (which is the value after reset), the baud rate is
oscillator frequency. If SMOD1 = 1, the baud rate is
the oscillator frequency:
14.3.6
In these modes the baud rate is variable and can be
generated alternatively by a baud rate generator or by
Timer 1.
2000 Jul 26
Mode 2 baud rate
handbook, full pagewidth
Mode 0 baud rate
Single-chip 8-bit microcontroller with CAN controller
Note: The switch configuration shows the reset state.
B
B
B
AUD
AUD
AUD
R
R
R
ATE IN
ATE IN
ATE IN
f CLK
=
=
2
--------------------
M
oscillator frequency
-------------------------------------------------------
M
SMOD1
M
32
ODE
ODE
ODE
Fig.24 Serial Port Input Clock when using the Baud Rate Generator.
BAUD RATE
clock
input
S0PSH
0
2
1
AND
oscillator frequency
6
.3 .2 .1 .0
3
12 BIT TIMER
S0PSL
1
32
1
16
of
overflow
of
63
14.3.7
In Modes 1 and 3, the P8xC591 can use an internal baud
rate generator for the serial port. To enable this feature, bit
SPS (bit 7 of Special Function Register S0PSH) must be
set. Bit SMOD1 (PCON.7) controls a divide-by-2 circuit
which affect the input and output clock signal of the baud
rate generator. After reset the divide-by-2 circuit is active
and the resulting overflow output clock will be divided by 2.
The input clock of the baud rate generator is f
The baud rate generator consists of its own free running
upward counting 12-bit timer. On overflow of this timer
(next count step after counter value FFFH) there is an
automatic 12-bit reload from the registers S0PSL and
S0PSH. The lower 8 bits of the timer are reloaded from
S0PSL, while the upper four bits are reloaded from bit 0 to
3 of register S0PSH. The baud rate timer is reloaded by
writing to S0PSH.
U
2
SING THE
0
1
(SMOD1)
I
PCON.7
NTERNAL
MHI025
B
AUD
Preliminary Specification
BAUD
RATE
CLOCK
R
ATE
G
P8xC591
ENERATOR
CLK.