PIC16F877-20/P Microchip Technology, PIC16F877-20/P Datasheet - Page 100

• Manufacturer Part Number: PIC16F877-20/P
• Description: IC MCU FLASH 8KX14 EE 40DIP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F877-20/P

• Core Size: 8-Bit
• Program Memory Size: 14KB (8K x 14)
• Core Processor: PIC
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 33
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 368 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Controller Family/series: PIC16F
• No. Of I/o's: 33
• Eeprom Memory Size: 256Byte
• Ram Memory Size: 368Byte
• Cpu Speed: 20MHz
• No. Of Timers: 3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 444-1001 - DEMO BOARD FOR PICMICRO MCU
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

PICmicro MID-RANGE MCU FAMILY
6.2.4.1
6.2.5
DS31006A-page 6-6
Computed GOTO
Stack
A computed GOTO is accomplished by adding an offset to the program counter (ADDWF PCL).
When doing a table read using a computed GOTO method, care should be exercised if the table
location crosses a PCL memory boundary (each 256 byte block).
The stack allows a combination of up to 8 program calls and interrupts to occur. The stack con-
tains the return address from this branch in program execution.
Mid-Range MCU devices have an 8-level deep x 13-bit wide hardware stack. The stack space is
not part of either program or data space and the stack pointer is not readable or writable. The PC
is PUSHed onto the stack when a CALL instruction is executed or an interrupt causes a branch.
The stack is POPed in the event of a RETURN, RETLW or a RETFIE instruction execution. PCLATH
is not modified when the stack is PUSHed or POPed.
After the stack has been PUSHed eight times, the ninth push overwrites the value that was stored
from the first push. The tenth push overwrites the second push (and so on). An example of the
overwriting of the stack is shown in
Figure 6-3: Stack Modification
Note:
Note 1: There are no status bits to indicate stack overflow or stack underflow conditions.
Note 2: There are no instructions/mnemonics called PUSH or POP. These are actions that
Any write to the Program Counter (PCL), will cause the lower five bits of the PCLATH
to be loaded into PCH.
occur from the execution of the CALL, RETURN, RETLW, and RETFIE instructions,
or the vectoring to an interrupt address.
Push1 Push9
Push2 Push10
Push3
Push4
Push5
Push6
Push7
Push8
STACK
Figure
6-3.
Top of STACK
1997 Microchip Technology Inc.