PIC18F4520-I/P Microchip Technology Inc., PIC18F4520-I/P Datasheet - Page 43

• Manufacturer Part Number: PIC18F4520-I/P
• Description: 40 Pin, 32 KB Flash, 1536 RAM, 36 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F4520-I/P

• A/d Inputs: 13-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 10 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 36
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 40-pin PDIP
• Programmable Memory: 32K Bytes
• Ram Size: 1.5K Bytes
• Speed: 40 MHz
• Timers: 1-8-bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

4.0
The PIC18F2420/2520/4420/4520 devices differentiate
between various kinds of Reset:
a)
b)
c)
d)
e)
f)
g)
h)
This section discusses Resets generated by MCLR,
POR and BOR and covers the operation of the various
start-up timers. Stack Reset events are covered in
Section 5.1.2.4 “Stack Full and Underflow Resets”.
WDT Resets are covered in Section 23.2 “Watchdog
Timer (WDT)”.
FIGURE 4-1:
 2004 Microchip Technology Inc.
OSC1
MCLR
V
Note 1: This is the INTRC source from the internal oscillator block and is separate from the RC oscillator of the CLKI pin.
Power-on Reset (POR)
MCLR Reset during normal operation
MCLR Reset during power managed modes
Watchdog Timer (WDT) Reset (during
execution)
Programmable Brown-out Reset (BOR)
RESET Instruction
Stack Full Reset
Stack Underflow Reset
DD
RESET
2: See Table 4-2 for time-out situations.
Instruction
INTRC
RESET
OST/PWRT
Pointer
32 s
Stack
( )_IDLE
Brown-out
Time-out
V
(1)
Detect
Sleep
DD
WDT
Reset
Rise
OST
SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
PWRT
Stack Full/Underflow Reset
External Reset
MCLRE
10-bit Ripple Counter
11-bit Ripple Counter
POR Pulse
BOREN
1024 Cycles
65.5 ms
PIC18F2420/2520/4420/4520
Preliminary
A simplified block diagram of the On-Chip Reset Circuit
is shown in Figure 4-1.
4.1
Device Reset events are tracked through the RCON
register (Register 4-1). The lower five bits of the regis-
ter indicate that a specific Reset event has occurred. In
most cases, these bits can only be cleared by the event
and must be set by the application after the event. The
state of these flag bits, taken together, can be read to
indicate the type of Reset that just occurred. This is
described in more detail in Section 4.6 “Reset State
of Registers”.
The RCON register also has control bits for setting
interrupt priority (IPEN) and software control of the
BOR (SBOREN). Interrupt priority is discussed in
Section 9.0
Section 4.4 “Brown-out Reset (BOR)”.
RCON Register
“Interrupts”.
S
R
BOR
DS39631A-page 41
Q
is
Enable OST
Enable PWRT
Chip_Reset
covered
(2)
in