AT90S8535-8PC Atmel, AT90S8535-8PC Datasheet - Page 24
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AT90S8535-8PC
Manufacturer Part Number
AT90S8535-8PC
Description
IC MCU 8K FLSH 8MHZ A/D 40DIP
Manufacturer
Atmel
Series
AVR® 90Sr
Specifications of AT90S8535-8PC
Core Processor
AVR
Core Size
8-Bit
Speed
8MHz
Connectivity
SPI, UART/USART
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
32
Program Memory Size
8KB (4K x 16)
Program Memory Type
FLASH
Eeprom Size
512 x 8
Ram Size
512 x 8
Voltage - Supply (vcc/vdd)
4 V ~ 6 V
Data Converters
A/D 8x10b
Oscillator Type
Internal
Operating Temperature
0°C ~ 70°C
Package / Case
40-DIP (0.600", 15.24mm)
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
AT90S8535-8PC
Manufacturer:
ATMEL/爱特梅尔
Quantity:
20 000
Watchdog Reset
MCU Status Register –
MCUSR
24
AT90S/LS8535
When the Watchdog times out, it will generate a short reset pulse of 1 XTAL cycle dura-
tion. On the falling edge of this pulse, the delay timer starts counting the Time-out period
t
Figure 27. Watchdog Reset during Operation
The MCU Status Register provides information on which reset source caused an MCU
reset.
• Bits 7..2 – Res: Reserved Bits
These bits are reserved bits in the AT90S8535 and always read as zero.
• Bit 1 – EXTRF: External Reset Flag
After a power-on reset, this bit is undefined (X). It can only be set by an External Reset.
A Watchdog Reset will leave this bit unchanged. The bit is cleared by writing a logical
zero to the bit.
• Bit 0 – PORF: Power-on Reset Flag
This bit is only set by a Power-on Reset. A Watchdog Reset or an External Reset will
leave this bit unchanged. The bit is cleared by writing a logical zero to the bit.
To summarize, Table 5 shows the value of these two bits after the three modes of reset.
Table 5. PORF and EXTRF Values after Reset
To make use of these bits to identify a reset condition, the user software should clear
both the PORF and EXTRF bits as early as possible in the program. Checking the
PORF and EXTRF values is done before the bits are cleared. If the bit is cleared before
an External or Watchdog Reset occurs, the source of reset can be found by using Table
6.
TOUT
Bit
$34 ($54)
Read/Write
Initial Value
Reset Source
Power-on Reset
External Reset
Watchdog Reset
. Refer to page 49 for details on operation of the Watchdog.
R
7
–
0
R
6
–
0
R
5
–
0
R
4
–
0
Unchanged
Undefined
EXTRF
1
R
3
–
0
R
2
–
0
EXTRF
See Bit Description
R/W
1
Unchanged
Unchanged
PORF
PORF
R/W
1
0
1041H–11/01
MCUSR