AT89S51-24PU Atmel, AT89S51-24PU Datasheet - Page 10
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AT89S51-24PU
Manufacturer Part Number
AT89S51-24PU
Description
IC MCU 4K FLASH 24MHZ 40-DIP
Manufacturer
Atmel
Series
89Sr
Specifications of AT89S51-24PU
Core Processor
8051
Core Size
8-Bit
Speed
24MHz
Connectivity
UART/USART
Peripherals
WDT
Number Of I /o
32
Program Memory Size
4KB (4K x 8)
Program Memory Type
FLASH
Ram Size
128 x 8
Voltage - Supply (vcc/vdd)
4 V ~ 5.5 V
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
40-DIP (0.600", 15.24mm)
Processor Series
AT89x
Core
8051
Data Bus Width
8 bit
Data Ram Size
128 B
Interface Type
ISP/UART
Maximum Clock Frequency
24 MHz
Number Of Programmable I/os
32
Number Of Timers
2
Operating Supply Voltage
4 V to 5.5 V
Maximum Operating Temperature
+ 85 C
Mounting Style
Through Hole
3rd Party Development Tools
PK51, CA51, A51, ULINK2
Development Tools By Supplier
AT89ISP
Minimum Operating Temperature
- 40 C
Controller Family/series
(8051) 8052
No. Of I/o's
32
Ram Memory Size
128Byte
Cpu Speed
24MHz
No. Of Timers
2
Rohs Compliant
Yes
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Eeprom Size
-
Data Converters
-
Lead Free Status / Rohs Status
Lead free / RoHS Compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
AT89S51-24PU
Manufacturer:
ATMEL
Quantity:
101 380
Company:
Part Number:
AT89S51-24PU
Manufacturer:
ATM
Quantity:
5 120
Company:
Part Number:
AT89S51-24PU
Manufacturer:
RENESA
Quantity:
5 194
Company:
Part Number:
AT89S51-24PU
Manufacturer:
AT
Quantity:
5
Part Number:
AT89S51-24PU
Manufacturer:
ATMEL/爱特梅尔
Quantity:
20 000
7.2
8. UART
9. Timer 0 and 1
10
WDT During Power-down and Idle
AT89S51
every 16383 machine cycles. To reset the WDT the user must write 01EH and 0E1H to
WDTRST. WDTRST is a write-only register. The WDT counter cannot be read or written. When
WDT overflows, it will generate an output RESET pulse at the RST pin. The RESET pulse dura-
tion is 98xTOSC, where TOSC = 1/FOSC. To make the best use of the WDT, it should be
serviced in those sections of code that will periodically be executed within the time required to
prevent a WDT reset.
In Power-down mode the oscillator stops, which means the WDT also stops. While in Power-
down mode, the user does not need to service the WDT. There are two methods of exiting
Power-down mode: by a hardware reset or via a level-activated external interrupt, which is
enabled prior to entering Power-down mode. When Power-down is exited with hardware reset,
servicing the WDT should occur as it normally does whenever the AT89S51 is reset. Exiting
Power-down with an interrupt is significantly different. The interrupt is held low long enough for
the oscillator to stabilize. When the interrupt is brought high, the interrupt is serviced. To prevent
the WDT from resetting the device while the interrupt pin is held low, the WDT is not started until
the interrupt is pulled high. It is suggested that the WDT be reset during the interrupt service for
the interrupt used to exit Power-down mode.
To ensure that the WDT does not overflow within a few states of exiting Power-down, it is best to
reset the WDT just before entering Power-down mode.
Before going into the IDLE mode, the WDIDLE bit in SFR AUXR is used to determine whether
the WDT continues to count if enabled. The WDT keeps counting during IDLE (WDIDLE bit = 0)
as the default state. To prevent the WDT from resetting the AT89S51 while in IDLE mode, the
user should always set up a timer that will periodically exit IDLE, service the WDT, and reenter
IDLE mode.
With WDIDLE bit enabled, the WDT will stop to count in IDLE mode and resumes the count
upon exit from IDLE.
The UART in the AT89S51 operates the same way as the UART in the AT89C51. For further
information on the UART operation, please click on the document link below:
Timer 0 and Timer 1 in the AT89S51 operate the same way as Timer 0 and Timer 1 in the
AT89C51. For further information on the timers’ operation, please click on the document link
below:
http://www.atmel.com/dyn/resources/prod_documents/DOC4316.PDF
http://www.atmel.com/dyn/resources/prod_documents/DOC4316.PDF
2487D–MICRO–6/08