P8XCL580HFT View Datasheet(PDF) - Philips Electronics
Part Name
Description
MFG CO.
'P8XCL580HFT' PDF : 80 Pages View PDF
Philips Semiconductors
Low voltage 8-bit microcontrollers with
UART, I2C-bus and ADC
Product specification
P80CL580; P83CL580
16.3 Baud rates
The baud rate in Mode 0 is fixed and may be calculated as:
Baud Rate = f--1o---s2--c-
The baud rate in Mode 2 depends on the value of the
SMOD bit in Special Function Register PCON and may be
calculated as:
Baud Rate = -2---S--6-M--4--O---D-- × fosc
• If SMOD = 0 (value on reset), the baud rate is 1⁄64 × fosc
• If SMOD = 1, the baud rate is 1⁄32 × fosc
The baud rates in Modes 1 and 3 are determined by the
Timer 1 or Timer 2 overflow rate.
16.3.1 USING TIMER 1 TO GENERATE BAUD RATES
When Timer 1 is used as the Baud Rate Generator, the
baud rates in Modes 1 and 3 are determined by the
Timer 1 overflow rate and the value of the SMOD bit as
follows:
Baud Rate = 2----S--3-M--2--O---D-- × Timer 1 Overflow Rate.
The Timer 1 interrupt should be disabled in this
application. The Timer itself can be configured for either
‘timer’ or ‘counter’ operation in any of its 3 running modes.
In most typical applications, it is configured for ‘timer’
operation, in the Auto-reload mode (high nibble of
TMOD = 0010B). In this case the baud rate is given by the
formula:
Baud Rate = 2----S--3-M--2--O---D-- × -{----1---2-----×------(--2---f-5-o--6-s--c--–----T----H-----1----)---}---
By configuring Timer 1 to run as a 16-bit timer (high nibble
of TMOD = 0001B), and using the Timer 1 interrupt to do
a 16-bit software reload, very low baud rates can be
achieved. Table 33 lists commonly used baud rates and
how they can be obtained from Timer 1.
Table 33 Commonly used baud rates generated by Timer 1
BAUD RATE(kb/s)
fosc (MHz)
SMOD
C/T
1 000.0(1)
12.000
X(2)
X
375.0(3)
12.000
1
X
62.5(4)
12.000
1
0
19.2
11.059
1
0
9.6
11.059
0
0
4.8
11.059
0
0
2.4
11.059
0
0
1.2
11.059
0
0
137.5
11.986
0
0
110.0
6.000
0
0
110.0
12.000
0
0
Notes
1. Maximum in Mode 0.
2. X = don’t care.
3. Maximum in Mode 2.
4. Maximum in Modes 1 and 3.
TIMER 1 MODE
X
X
Mode 2
Mode 2
Mode 2
Mode 2
Mode 2
Mode 2
Mode 2
Mode 2
Mode 1
RELOAD VALUE
X
X
FFH
FDH
FDH
FAH
F4H
E8H
1DH
72H
FEEBH
1997 Mar 14
35
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