PIC16F913-I/SP Microchip Technology Inc., PIC16F913-I/SP Datasheet - Page 31

• Manufacturer Part Number: PIC16F913-I/SP
• Description: 28 PIN, 7 KB FLASH, 352 RAM, 25 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F913-I/SP

• A/d Inputs: 5-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 25
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 28-pin SPDIP
• Programmable Memory: 7K Bytes
• Ram Size: 256 Bytes
• Speed: 20 MHz
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

2.3
The Program Counter (PC) is 13 bits wide. The low
byte comes from the PCL register, which is a readable
and writable register. The high byte (PC<12:8>) is not
directly readable or writable and comes from
PCLATH. On any Reset, the PC is cleared. Figure 2-5
shows the two situations for the loading of the PC. The
upper example in Figure 2-5 shows how the PC is
loaded on a write to PCL (PCLATH<4:0>
The lower example in Figure 2-5 shows how the PC is
loaded
(PCLATH<4:3>
FIGURE 2-5:
2.3.1
A computed GOTO is accomplished by adding an offset
to the program counter (ADDWF PCL). When perform-
ing 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). Refer to the
Application Note AN556, “Implementing a Table Read”
(DS00556).
2.3.2
The
8-level x 13-bit wide hardware stack (see Figures 2-1
and 2-2). 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 affected by a PUSH or POP operation.
The stack operates as a circular buffer. This means that
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).
© 2005 Microchip Technology Inc.
PC
PC
12
12 11 10
2
PIC16F917/916/914/913
PCL and PCLATH
during
PCH
5
PCLATH<4:3>
PCH
COMPUTED GOTO
STACK
PCLATH
PCLATH<4:0>
8
PCLATH
8
a
PCH).
7
7
LOADING OF PC IN
DIFFERENT SITUATIONS
CALL
PCL
PCL
or
11
8
family
GOTO
0
0
OPCODE<10:0>
ALU Result
GOTO, CALL
Instruction with
instruction
has
Destination
PCL as
PCH).
Preliminary
an
PIC16F917/916/914/913
2.4
All PIC16F917/916/914/913 devices are capable of
addressing a continuous 8K word block of program
memory. The CALL and GOTO instructions provide only
11 bits of address to allow branching within any 2K pro-
gram memory page. When doing a CALL or GOTO
instruction, the upper 2 bits of the address are provided
by PCLATH<4:3>. When doing a CALL or GOTO instruc-
tion, the user must ensure that the page select bits are
programmed so that the desired program memory
page is addressed. If a return from a CALL instruction
(or interrupt) is executed, the entire 13-bit PC is POPed
off
PCLATH<4:3> bits is not required for the RETURN
instructions (which POPs the address from the stack).
Example 2-1 shows the calling of a subroutine in
page 1 of the program memory. This example assumes
that PCLATH is saved and restored by the Interrupt
Service Routine (if interrupts are used).
EXAMPLE 2-1:
SUB1_P1
Note:
Note 1: There are no Status bits to indicate stack
the
2: There are no instructions/mnemonics
Program Memory Paging
stack.
ORG 0x500
BCF PCLATH,4
BSF PCLATH,3
CALL SUB1_P1
:
:
ORG 0x900
:
:
RETURN
The contents of the PCLATH register are
unchanged after a RETURN or RETFIE
instruction is executed. The user must
rewrite the contents of the PCLATH regis-
ter for any subsequent subroutine calls or
GOTO instructions.
overflow or stack underflow conditions.
called PUSH or POP. These are actions
that occur from the execution of the CALL,
RETURN,
tions or the vectoring to an interrupt
address.
Therefore,
CALL OF A SUBROUTINE
IN PAGE 1 FROM PAGE 0
RETLW and RETFIE instruc-
;Select page 1
;(800h-FFFh)
;Call subroutine in
;page 1 (800h-FFFh)
;page 1 (800h-FFFh)
;called subroutine
;page 1 (800h-FFFh)
;return to
;Call subroutine
;in page 0
;(000h-7FFh)
manipulation
DS41250E-page 29
of
the