AT89LP428-20MU ATMEL [ATMEL Corporation], AT89LP428-20MU Datasheet - Page 80

• Manufacturer Part Number: AT89LP428-20MU
• Description: 8-bit Microcontroller with 4K/8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

16.2.2
80
AT89LP428/828
Using Timer 2 to Generate Baud Rates
Programmers can achieve very low baud rates with Timer 1 by configuring the Timer to run as a
16-bit auto-reload timer (high nibble of TMOD = 0001B). In this case, the baud rate is given by
the following formula.
Table 16-2
Table 16-2.
Timer 2 is selected as the baud rate generator by setting TCLK and/or RCLK in T2CON. Under
these conditions, the baud rates for transmit and receive can be simultaneously different by
using Timer 1 for transmit and Timer 2 for receive, or vice versa. The baud rate generator mode
is similar to the auto-reload mode, in that a rollover causes the Timer 2 registers to be reloaded
with the 16-bit value in registers RCAP2H and RCAP2L, which are preset by software. In this
case, the baud rates in Modes 1 and 3 are determined by Timer 2’s overflow rate according to
the following equation:.
Table 16-3
Mode 0: 1 MHz
Mode 2: 750K
Baud Rate
62.5K
38.4K
19.2K
137.5
9.6K
4.8K
2.4K
1.2K
110
110
lists commonly used baud rates and how they can be obtained from Timer 1.
lists commonly used baud rates and how they can be obtained from Timer 2.
Commonly Used Baud Rates Generated by Timer 1 (TPS = 0000B)
Modes 1 and 3
Baud Rate
Modes 1, 3
Baud Rate
f
OSC
11.986
11.059
11.059
11.059
11.059
11.059
11.059
12
12
12
(MHz)
4
6
=
=
----- -
16
2
------------------- -
1
SMOD1
32
×
-------------------------------------------------------------------------------- -
[
65536
SMOD1
×
Oscillator Frequency
0
1
1
0
1
0
0
0
0
0
0
0
------------------------------------------------------- -
[
Oscillator Frequency
65536
–
(
RCAP2H,RCAP2L
–
(
RH1,RL1
C/T
X
X
0
0
0
0
0
0
0
0
0
0
)
]
×
)
-------------------- -
TPS
]
Mode
×
Timer 1
X
X
2
2
2
2
2
2
1
1
1
1
1
-------------------- -
TPS
+
1
1
+
1
3654A–MICRO–8/09
Reload Value
FEE0H
F55CH
F958H
F304H
DCH
DCH
F4H
F7H
B8H
70H
X
X