AT89S53-24AI Atmel, AT89S53-24AI Datasheet - Page 10
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AT89S53-24AI
Manufacturer Part Number
AT89S53-24AI
Description
IC MICRO CTRL 24MHZ 44TQFP
Manufacturer
Atmel
Series
89Sr
Datasheet
1.AT89S53-24JI.pdf
(35 pages)
Specifications of AT89S53-24AI
Core Processor
8051
Core Size
8-Bit
Speed
24MHz
Connectivity
SPI, UART/USART
Peripherals
WDT
Number Of I /o
32
Program Memory Size
12KB (12K x 8)
Program Memory Type
FLASH
Ram Size
256 x 8
Voltage - Supply (vcc/vdd)
4 V ~ 6 V
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
44-TQFP, 44-VQFP
Data Bus Width
8 bit
Data Ram Size
256 B
Interface Type
SPI, UART
Maximum Clock Frequency
24 MHz
Number Of Programmable I/os
32
Number Of Timers
3 x 16 bit
Operating Supply Voltage
4 V to 6 V
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
Minimum Operating Temperature
- 40 C
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Eeprom Size
-
Data Converters
-
Lead Free Status / Rohs Status
No
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
AT89S53-24AI
Manufacturer:
HIROSE
Quantity:
101
Part Number:
AT89S53-24AI
Manufacturer:
ATMEL/爱特梅尔
Quantity:
20 000
Capture Mode
In the capture mode, two options are selected by bit
EXEN2 in T2CON. If EXEN2 = 0, Timer 2 is a 16-bit timer
or counter which upon overflow sets bit TF2 in T2CON.
This bit can then be used to generate an interrupt. If
EXEN2 = 1, Timer 2 performs the same operation, but a l-
to-0 transition at external input T2EX also causes the
Figure 1. Timer 2 in Capture Mode
Auto-reload (Up or Down Counter)
Timer 2 can be programmed to count up or down when
configured in its 16-bit auto-reload mode. This feature is
invoked by the DCEN (Down Counter Enable) bit located in
the SFR T2MOD (see Table 9). Upon reset, the DCEN bit
is set to 0 so that timer 2 will default to count up. When
DCEN is set, Timer 2 can count up or down, depending on
the value of the T2EX pin.
Figure 2 shows Timer 2 automatically counting up when
DCEN = 0. In this mode, two options are selected by bit
EXEN2 in T2CON. If EXEN2 = 0, Timer 2 counts up to
0FFFFH and then sets the TF2 bit upon overflow. The over-
flow also causes the timer registers to be reloaded with the
16-bit value in RCAP2H and RCAP2L. The values in
RCAP2H and RCAP2L are preset by software. If EXEN2 =
1, a 16-bit reload can be triggered either by an overflow or
by a 1-to-0 transition at external input T2EX. This transition
also sets the EXF2 bit. Both the TF2 and EXF2 bits can
generate an interrupt if enabled.
Setting the DCEN bit enables Timer 2 to count up or down,
as shown in Figure 3. In this mode, the T2EX pin controls
the direction of the count. A logic 1 at T2EX makes Timer 2
10
T2EX PIN
OSC
AT89S53
T2 PIN
÷12
TRANSITION
DETECTOR
C/T2 = 0
C/T2 = 1
EXEN2
TR2
CAPTURE
CONTROL
CONTROL
current value in TH2 and TL2 to be captured into RCAP2H
and RCAP2L, respectively. In addition, the transition at
T2EX causes bit EXF2 in T2CON to be set. The EXF2 bit,
like TF2, can generate an interrupt. The capture mode is
illustrated in Figure 1.
count up. The timer will overflow at 0FFFFH and set the
TF2 bit. This overflow also causes the 16-bit value in
RCAP2H and RCAP2L to be reloaded into the timer regis-
ters, TH2 and TL2, respectively.
A logic 0 at T2EX makes Timer 2 count down. The timer
underflows when TH2 and TL2 equal the values stored in
RCAP2H and RCAP2L. The underflow sets the TF2 bit and
causes 0FFFFH to be reloaded into the timer registers.
The EXF2 bit toggles whenever Timer 2 overflows or
underflows and can be used as a 17th bit of resolution. In
this operating mode, EXF2 does not flag an interrupt.
RCAP2H
TH2
EXF2
RCAP2L
TL2
OVERFLOW
TF2
INTERRUPT
0787E–MICRO–3/06
TIMER 2