參數(shù)資料
型號: 89LS8252
廠商: Atmel Corp.
英文描述: 8-Bit Microcontroller with 8K Bytes Flash
中文描述: 8位具有8K字節(jié)的閃存,微控制器
文件頁數(shù): 13/31頁
文件大?。?/td> 470K
代理商: 89LS8252
AT89LS8252
4-149
Baud Rate Generator
Timer 2 is selected as the baud rate generator by setting
TCLK and/or RCLK in T2CON (Table 2). Note that the baud
rates for transmit and receive can be different if Timer 2 is
used for the receiver or transmitter and Timer 1 is used for
the other function. Setting RCLK and/or TCLK puts Timer 2
into its baud rate generator mode, as shown in Figure 4.
The baud rate generator mode is similar to the auto-reload
mode, in that a rollover in TH2 causes the Timer 2 registers
to be reloaded with the 16 bit value in registers RCAP2H
and RCAP2L, which are preset by software.
The baud rates in Modes 1 and 3 are determined by Timer
2’s overflow rate according to the following equation.
The Timer can be configured for either timer or counter
operation. In most applications, it is configured for timer
operation (CP/T2 = 0). The timer operation is different for
Timer 2 when it is used as a baud rate generator. Normally,
as a timer, it increments every machine cycle (at 1/12 the
oscillator frequency). As a baud rate generator, however, it
increments every state time (at 1/2 the oscillator fre-
quency). The baud rate formula is given below.
where (RCAP2H, RCAP2L) is the content of RCAP2H and
RCAP2L taken as a 16 bit unsigned integer.
Timer 2 as a baud rate generator is shown in Figure 4. This
figure is valid only if RCLK or TCLK = 1 in T2CON. Note
that a rollover in TH2 does not set TF2 and will not gener-
ate an interrupt. Note too, that if EXEN2 is set, a 1-to-0
transition in T2EX will set EXF2 but will not cause a reload
from (RCAP2H, RCAP2L) to (TH2, TL2). Thus when Timer
2 is in use as a baud rate generator, T2EX can be used as
an extra external interrupt.
Note that when Timer 2 is running (TR2 = 1) as a timer in
the baud rate generator mode, TH2 or TL2 should not be
read from or written to. Under these conditions, the Timer is
incremented every state time, and the results of a read or
write may not be accurate. The RCAP2 registers may be
read but should not be written to, because a write might
overlap a reload and cause write and/or reload errors. The
timer should be turned off (clear TR2) before accessing the
Timer 2 or RCAP2 registers.
Modes 1 and 3 Baud Rates
Timer 2 Overflow Rate
16
-----------------------------------------------------------
=
Modes 1 and 3
Baud Rate
---------------------------------------
65536
RCAP2H,RCAP2L
(
32
)
[
]
×
----------------------------------------------------------------------------------------------
=
Figure 5.
Timer 2 in Clock-Out Mode
相關(guān)PDF資料
PDF描述
89LV55 8-Bit Microcontroller with 20K Bytes Flash
89S8252 8-Bit Microcontroller with 8K Bytes Flash
8M052489 8m Class DC to AC Inverter
8T26A 8-Channel, 10-Bit ADC with I2C Compatible Interface in 20-Lead TSSOP; Package: TSSOP; No of Pins: 20; Temperature Range: Industrial
8T95 8-Channel, 10-Bit ADC with I2C Compatible Interface in 20-Lead TSSOP; Package: TSSOP; No of Pins: 20; Temperature Range: Industrial
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
89LV1632 制造商:MAXWELL 制造商全稱:Maxwell Technologies 功能描述:16 Megabit (512K x 32-Bit) Low Voltage MCM SRAM
89LV1632RPQE-30 制造商:MAXWELL 制造商全稱:Maxwell Technologies 功能描述:16 Megabit (512K x 32-Bit) Low Voltage MCM SRAM
89LV1632RPQH-30 制造商:MAXWELL 制造商全稱:Maxwell Technologies 功能描述:16 Megabit (512K x 32-Bit) Low Voltage MCM SRAM
89LV1632RPQI-30 制造商:MAXWELL 制造商全稱:Maxwell Technologies 功能描述:16 Megabit (512K x 32-Bit) Low Voltage MCM SRAM
89LV1632RPQK-30 制造商:MAXWELL 制造商全稱:Maxwell Technologies 功能描述:16 Megabit (512K x 32-Bit) Low Voltage MCM SRAM