PIC18F8722-E/PT Microchip Technology, PIC18F8722-E/PT Datasheet - Page 69

• Manufacturer Part Number: PIC18F8722-E/PT
• Description: IC PIC MCU FLASH 64KX16 80TQFP
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F8722-E/PT

• Core Size: 8-Bit
• Program Memory Size: 128KB (64K x 16)
• Oscillator Type: Internal
• Core Processor: PIC
• Speed: 25MHz
• Connectivity: EBI/EMI, I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, HLVD, POR, PWM, WDT
• Number Of I /o: 70
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 3.8K x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 16x10b
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 80-TFQFP
• Controller Family/series: PIC18
• No. Of I/o's: 70
• Eeprom Memory Size: 1024Byte
• Ram Memory Size: 3936Byte
• Cpu Speed: 40MHz
• Processor Series: PIC18F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 3936 B
• Interface Type: SPI, I2C, EUSART
• Maximum Clock Frequency: 40 MHz
• Number Of Programmable I/os: 70
• Number Of Timers: 5
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734, 52712-325, EWPIC18
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, ICE4000, DM183032, DM183022, DV164136
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 16 Channel
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: DV164136 - DEVELOPMENT KIT FOR PIC18XLT80PT3 - SOCKET TRAN ICE 80MQFP/TQFPAC164320 - MODULE SKT MPLAB PM3 80TQFPAC174011 - MODULE SKT PROMATEII 80TQFP
• Lead Free Status / Rohs Status: Details

5.1.3.2
The STKPTR register (Register 5-1) contains the Stack
Pointer value, the STKFUL (Stack Full) status bit and
the STKUNF (Stack Underflow) status bits. The value
of the Stack Pointer can be 0 through 31. The Stack
Pointer increments before values are pushed onto the
stack and decrements after values are popped off the
stack. On Reset, the stack pointer value will be zero.
The user may read and write the stack pointer value.
This feature can be used by a Real-Time Operating
System (RTOS) for return stack maintenance.
After the PC is pushed onto the stack 31 times (without
popping any values off the stack), the STKFUL bit is
set. The STKFUL bit is cleared by software or by a
POR.
The action that takes place when the stack becomes
full depends on the state of the STVREN (Stack Over-
flow Reset Enable) configuration bit. (Refer to
Section 25.1 “Configuration Bits” for a description of
the device configuration bits.) If STVREN is set
(default), the 31st PUSH will push the (PC + 2) value
onto the stack, set the STKFUL bit and reset the
device. The STKFUL bit will remain set and the Stack
Pointer will be set to zero.
If STVREN is cleared, the STKFUL bit will be set on the
31st PUSH and the Stack Pointer will increment to 31.
Any additional pushes will not overwrite the 31st PUSH
and STKPTR will remain at 31.
REGISTER 5-1:
 2004 Microchip Technology Inc.
bit 7
bit 6
bit 5
bit 4-0
Return Stack Pointer (STKPTR)
STKPTR: STACK POINTER REGISTER
bit 7
STKFUL: Stack Full Flag bit
1 = Stack became full or overflowed
0 = Stack has not become full or overflowed
STKUNF: Stack Underflow Flag bit
1 = Stack underflow occurred
0 = Stack underflow did not occur
Unimplemented: Read as ‘0’
SP4:SP0: Stack Pointer Location bits
Legend:
R = Readable bit
-n = Value at POR
STKFUL
Note 1: Bit 7 and bit 6 are cleared by user software or by a POR.
R/C-0
(1)
STKUNF
R/C-0
(1)
W = Writable bit
‘1’ = Bit is set
Preliminary
(1)
U-0
—
(1)
R/W-0
When the stack has been popped enough times to
unload the stack, the next POP will return a value of
zero to the PC and set the STKUNF bit, while the Stack
Pointer remains at zero. The STKUNF bit will remain
set until cleared by software or until a POR occurs.
5.1.3.3
Since the Top-of-Stack is readable and writable, the
ability to push values onto the stack and pull values off
the stack without disturbing normal program execution
is a desirable feature. The PIC18 instruction set
includes two instructions, PUSH and POP, that permit
the TOS to be manipulated under software control.
TOSU, TOSH and TOSL can be modified to place data
or a return address on the stack.
The PUSH instruction places the current PC value onto
the stack. This increments the Stack Pointer and loads
the current PC value onto the stack.
The POP instruction discards the current TOS by decre-
menting the Stack Pointer. The previous value pushed
onto the stack then becomes the TOS value.
SP4
PIC18F8722 FAMILY
Note:
U = Unimplemented
‘0’ = Bit is cleared
R/W-0
Returning a value of zero to the PC on an
underflow has the effect of vectoring the
program to the Reset vector, where the
stack conditions can be verified and
appropriate actions can be taken. This is
not the same as a Reset, as the contents
of the SFRs are not affected.
SP3
PUSH and POP Instructions
R/W-0
SP2
C = Clearable only bit
x = Bit is unknown
R/W-0
SP1
DS39646B-page 67
R/W-0
SP0
bit 0