AT89S2051 Atmel Corporation, AT89S2051 Datasheet - Page 8
![no-image](/images/manufacturer_photos/0/0/79/atmel_corporation_sml.jpg)
AT89S2051
Manufacturer Part Number
AT89S2051
Description
Manufacturer
Atmel Corporation
Specifications of AT89S2051
Flash (kbytes)
2 Kbytes
Max. Operating Frequency
24 MHz
Cpu
8051-12C
Max I/o Pins
15
Uart
1
Sram (kbytes)
0.25
Operating Voltage (vcc)
2.7 to 5.5
Timers
2
Isp
SPI
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
AT89S2051-24PI
Manufacturer:
ATMEL
Quantity:
918
Company:
Part Number:
AT89S2051-24PU
Manufacturer:
ATMEL
Quantity:
2 300
Part Number:
AT89S2051-24PU
Manufacturer:
ATMEL/爱特梅尔
Quantity:
20 000
Company:
Part Number:
AT89S2051-24SU
Manufacturer:
MICROCHIP
Quantity:
3 420
Part Number:
AT89S2051-24SU
Manufacturer:
ATMEL/爱特梅尔
Quantity:
20 000
10. Reset
10.1
Figure 10-1. Power-up and Brown-out Detection Sequence
8
Min V
Power-On Reset
BOD Level 2.3V
POR Level 1.4V
AT89S2051/S4051
CC
Level 2.7V
Internal
RESET
XTAL1
POR
BOD
V
0
CC
During reset, all I/O Registers are set to their initial values, the port pins are weakly pulled to
V
has three sources of reset: power-on reset, brown-out reset, and external reset.
A Power-On Reset (POR) is generated by an on-chip detection circuit. The detection level is
nominally 1.4V. The POR is activated whenever V
cuit can be used to trigger the start-up reset or to detect a supply voltage failure in devices
without a brown-out detector. The POR circuit ensures that the device is reset from power-on.
When V
XTAL Oscillator Bypass fuse is OFF). Only after V
detection) level (see
2-ms delay after which the Internal Reset is deasserted and the microcontroller starts executing.
The built-in 2-ms delay allows the V
ing, thus guaranteeing the maximum operating clock frequency. The POR signal is activated
again, without any delay, when V
a cold reset) will set the POF flag in PCON. Refer to
behavior.
CC
, and the program starts execution from the Reset Vector, 0000H. The AT89S2051/S4051
(2 ms)
t
POR
CC
reaches the Power-on Reset threshold voltage, the Pierce Oscillator is enabled (if the
2.4V
Section 10.2 ”Brown-out
CC
(2 ms)
falls below the POR threshold level. A Power-On Reset (i.e.
t
CC
POR
voltage to reach the minimum 2.7V level before execut-
1.2V
Reset”), the BOD delay counter starts measuring a
CC
CC
is below the detection level. The POR cir-
Figure 10-1
has also reached the BOD (brown-out
for details on the POR/BOD
(2 ms)
t
POR
3390E–MICRO–6/08
t
t
t
t
t