PIC18F4431-E/PT Microchip Technology, PIC18F4431-E/PT Datasheet - Page 93

• Manufacturer Part Number: PIC18F4431-E/PT
• Description: IC MCU FLASH 8KX16 44TQFP
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F4431-E/PT

• Core Size: 8-Bit
• Program Memory Size: 16KB (8K x 16)
• Oscillator Type: Internal
• Core Processor: PIC
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, Power Control PWM, QEI, POR, PWM, WDT
• Number Of I /o: 36
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 9x10b
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 44-TQFP, 44-VQFP
• Controller Family/series: PIC18
• No. Of I/o's: 36
• Eeprom Memory Size: 256Byte
• Ram Memory Size: 768Byte
• Cpu Speed: 40MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

9.0
The
multiple interrupt sources and an interrupt priority
feature that allows each interrupt source to be assigned
a high priority level or a low priority level. The high
priority interrupt vector is at 000008h and the low
priority interrupt vector is at 000018h. High priority
interrupt events will interrupt any low priority interrupts
that may be in progress.
There are ten registers which are used to control
interrupt operation. These registers are:
• RCON
• INTCON
• INTCON2
• INTCON3
• PIR1, PIR2, PIR3
• PIE1, PIE2, PIE3
• IPR1, IPR2, IPR3
It is recommended that the Microchip header files sup-
plied with MPLAB
names in these registers. This allows the assembler/
compiler to automatically take care of the placement of
these bits within the specified register.
In general, each interrupt source has three bits to con-
trol its operation. The functions of these bits are:
• Flag bit to indicate that an interrupt event
• Enable bit that allows program execution to
• Priority bit to select high priority or low priority
The interrupt priority feature is enabled by setting the
IPEN bit (RCON<7>). When interrupt priority is
enabled, there are two bits which enable interrupts
globally. Setting the GIEH bit (INTCON<7>) enables all
interrupts that have the priority bit set (high priority).
Setting the GIEL bit (INTCON<6>) enables all
interrupts that have the priority bit cleared (low priority).
When the interrupt flag, enable bit and appropriate
global interrupt enable bit are set, the interrupt will
vector immediately to address 000008h or 000018h,
depending on the priority bit setting. Individual
interrupts can be disabled through their corresponding
enable bits.
 2003 Microchip Technology Inc.
occurred
branch to the interrupt vector address when the
flag bit is set
(most interrupt sources have priority bits)
PIC18F2331/2431/4331/4431
INTERRUPTS
®
IDE be used for the symbolic bit
devices
PIC18F2331/2431/4331/4431
have
Preliminary
When the IPEN bit is cleared (default state), the inter-
rupt priority feature is disabled and interrupts are com-
patible
Compatibility mode, the interrupt priority bits for each
source have no effect. INTCON<6> is the PEIE bit,
which enables/disables all peripheral interrupt sources.
INTCON<7> is the GIE bit, which enables/disables all
interrupt sources. All interrupts branch to address
000008h in Compatibility mode.
When an interrupt is responded to, the Global Interrupt
Enable bit is cleared to disable further interrupts. If the
IPEN bit is cleared, this is the GIE bit. If interrupt priority
levels are used, this will be either the GIEH or GIEL bit.
High priority interrupt sources can interrupt a low
priority interrupt. Low priority interrupts are not
processed while high priority interrupts are in progress.
The return address is pushed onto the stack and the
PC is loaded with the interrupt vector address
(000008h or 000018h). Once in the interrupt service
routine, the source(s) of the interrupt can be
determined by polling the interrupt flag bits. The
interrupt flag bits must be cleared in software before re-
enabling interrupts to avoid recursive interrupts.
The “return from interrupt” instruction, RETFIE, exits
the interrupt routine and sets the GIE bit (GIEH or GIEL
if priority levels are used), which re-enables interrupts.
For external interrupt events, such as the INT pins or
the PORTB input change interrupt, the interrupt latency
will be three to four instruction cycles. The exact
latency is the same for one or two-cycle instructions.
Individual interrupt flag bits are set, regardless of the
status of their corresponding enable bit or the GIE bit.
Note:
with
Do not use the MOVFF instruction to modify
any of the interrupt control registers while
any interrupt is enabled. Doing so may
cause erratic microcontroller behavior.
PICmicro
®
mid-range
DS39616B-page 91
devices.
In