AT89S52-24JU Atmel, AT89S52-24JU Datasheet - Page 15
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AT89S52-24JU
Manufacturer Part Number
AT89S52-24JU
Description
IC MCU 8K FLASH 24MHZ 44-PLCC
Manufacturer
Atmel
Series
89Sr
Datasheet
1.AT89S52-24AU.pdf
(38 pages)
Specifications of AT89S52-24JU
Core Processor
8051
Core Size
8-Bit
Speed
24MHz
Connectivity
UART/USART
Peripherals
WDT
Number Of I /o
32
Program Memory Size
8KB (8K x 8)
Program Memory Type
FLASH
Ram Size
256 x 8
Voltage - Supply (vcc/vdd)
4 V ~ 5.5 V
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
44-PLCC
Package
44PLCC
Device Core
8051
Family Name
89S
Maximum Speed
24 MHz
Operating Supply Voltage
5 V
Data Bus Width
8 Bit
Number Of Programmable I/os
32
Interface Type
UART
Number Of Timers
3
Processor Series
AT89x
Core
8051
Data Ram Size
256 B
Maximum Clock Frequency
33 MHz
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
3rd Party Development Tools
PK51, CA51, A51, ULINK2
Development Tools By Supplier
AT89ISP
Minimum Operating Temperature
- 40 C
Eeprom Memory
0 Bytes
Input Output
32
Interface
UART
Memory Type
Flash
Number Of Bits
8
Package Type
44-pin PLCC
Programmable Memory
8K Bytes
Timers
3-16-bit
Voltage, Range
4-5.5 V
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Eeprom Size
-
Data Converters
-
Lead Free Status / Rohs Status
Lead free / RoHS Compliant
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Company
Part Number
Manufacturer
Quantity
Price
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11. Baud Rate Generator
1919D–MICRO–6/08
Timer 2 is selected as the baud rate generator by setting TCLK and/or RCLK in T2CON
5-2). 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
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 fol-
lowing equation.
The Timer can be configured for either timer or counter operation. In most applications, it is con-
figured 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 frequency). 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
TCLK = 1 in T2CON. Note that a rollover in TH2 does not set TF2 and will not generate an inter-
rupt. 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
Modes 1 and 3
-------------------------------------- -
Baud Rate
=
------------------------------------------------------------------------------------- -
32 x [65536-RCAP2H,RCAP2L)]
Oscillator Frequency
Figure
=
Timer 2 Overflow Rate
----------------------------------------------------------- -
11-1. This figure is valid only if RCLK or
Figure
16
11-1.
AT89S52
(Table
15